Lokasil 1, 2 and Gen 2 9A1 engines
11-06-2017, 11:35 PM
#46
Baz,
Thank you for this info! Might be a stupid question. But in your opinion.....What is the ideal way to warm up the car for colder climate drivers? Start and go, but keep rev's under some rpm level? Let is idle for a few mins, before driving it? Anything special? Is there a level of oil consumption that an owner should be suspicious of?
Thank you for this info! Might be a stupid question. But in your opinion.....What is the ideal way to warm up the car for colder climate drivers? Start and go, but keep rev's under some rpm level? Let is idle for a few mins, before driving it? Anything special? Is there a level of oil consumption that an owner should be suspicious of?
11-07-2017, 01:51 AM
#47
Doug H - we machine out the original cylinder and fit a new thick alloy cylinder (full wet liner) that is designed to accommodate any further shrinkage (which is unlikely as the engine will probably have just about finished I expect). By the way our rebuilds are usually around £8-£10K (for the whole car job) and significantly less for just engines.
f911 - Oil choice should be PK - avoid high torque pulling away in second (bore scoring worse at low revs and high torque) if driving fast use 1st.
Wayne - Not seen any evidence yet but early days.
Baz
f911 - Oil choice should be PK - avoid high torque pulling away in second (bore scoring worse at low revs and high torque) if driving fast use 1st.
Wayne - Not seen any evidence yet but early days.
Baz
11-07-2017, 05:34 AM
#48
User
Thread Starter
cvtbenhogan Sorry this is a misunderstanding in responding to a different post. Thicker oil is generally better as these engines wear but another correspondent pointed out that it could be too thick from cold and I responded that this might be true but then once the thicker oil is properly warmed up it will be thinner. So - a thicker oil is better for avoiding (or delaying) bore scoring and helping crankshaft shell life as the mileages exceed 50K.
shawn_nj This is a bigger problem than it seems at first. As engines produce more power (as they have done in this Porsche range over the previous 2 decades) the amount of heat generated when flat out increases and so the cars need more cooling capacity built into them so they survive when owners are exploiting their full potential.
However in contrast - in the UK (for example) most cars average around 30mph in their lifetime and anyway when drivers are obeying their Country's speed limits the power is much the same as it was years before and much smaller cooling capacity is required.
Several years ago now (when scoring became an issue) we conducted several tests on M96/7 cars to establish what was going on with different models. It was very time consuming and a labour of love to find the time but revealed very interesting results that helped us develop several products and modifications when we rebuild engines.
For our various tests we fitted temperature gauges inside various parts of the cylinder blocks and drove the cars in ambient conditions varying between 5 degrees C and 22 degrees C (over a year).
We fitted blanking covers to the radiators in different steps and covering part and full air flow and recorded the results when moving, stationary, following close behind other cars and lorries and on track.
We fitted different thermostats, different auxiliary thermostat housings and altered the coolant flow.
We found that for normal driving in town and up to 50mph one radiator was sufficient. For very fast driving in hot weather two radiators were sufficient. The only time we needed to use the third radiator (we had fitted) was on track following close behind another car and when stationary (at say lights) on a hot day after spirited driving.
From this we established that too much radiator capacity (combined with a thermostat placed at the entry to the engine and not the outlet as was more traditional) resulted in the thermostat being almost closed and the coolant flow being very slow (because the overkill amount of radiator area at the front forced the thermostat to almost close).
The engine splits the internal coolant flow so that by area about 10% goes into the cylinders and mixes back with the other 90% passing through the heads (so the differences cannot be measured unless you have internal gauges - as we did). The 10% splits off from a coolant tube at right angles (so is not best fro flow splitting).
There are therefore circumstances where the engine is at tickover - hardly any coolant is passing through the block and heat soak increases the cylinder surface temperature - thinning the oil and reducing it's ability to maintain a think film between the piston and the bore under the next imminent power run - so if a loose piece of Silicon gest stuck in between at that point - this is when damage can occur.
So we manufactured a thermostat housing for the 3rd radiator and advised owners not to rag the engine after a stop when it had been hot (and not to accelerate with too much throttle in 2nd in a tiptronic).
The 9A1 engine is similar in some ways and different in others. The M96/7 allows the cylinders to heat up more quickly as they are thin and they run with bigger piston clearances anyway. The 9A1 has smaller piston clearances and a different piston shape - that in all normal circumstances would contribute to it being a better engine (which it is). However the alloy castings near the bottom of the cylinders are all part of the block and are thick (holding the crankshaft shells) and these will take longer to heat through and allow the bottom of the block to expand.
If there had not been any stress relieving going on - that would have been OK but as the bottom of the cylinders (at one end of the crankcases) of all the engines we measured - shows shrinkage - that already reduces the piston clearance such that if the piston expands quicker than the block it may become too tight and "cold seize".
It is difficult to find a way to avoid damage resulting except to heat up the pistons more slowly (allowing time for the coolant and block to heat up and expand).
We do not have the resources to find out much more at this stage but I doubt that normal modest speeds (say up to a third throttle opening) would cause damage and that it takes about 15 minutes to warm the engine through.
In cold weather it would be better if the cars had been fitted with a radiator or air intake to the cooling system blind (to isolate a radiator and reduce cooling capacity until it was needed). Perhaps in sub zero climates (at part of the year) a cover could be fitted to one radiator beneficially).
I don't think allowing the car to stand ticking over from cold is necessary (or a good idea) probably best just to drive with restraint.
If an owners only drive is up to say 15 minutes long - I think they either should restrain their driving speeds or consider a different car - or wait until they have a longer drive to experience the performance.
Baz
shawn_nj This is a bigger problem than it seems at first. As engines produce more power (as they have done in this Porsche range over the previous 2 decades) the amount of heat generated when flat out increases and so the cars need more cooling capacity built into them so they survive when owners are exploiting their full potential.
However in contrast - in the UK (for example) most cars average around 30mph in their lifetime and anyway when drivers are obeying their Country's speed limits the power is much the same as it was years before and much smaller cooling capacity is required.
Several years ago now (when scoring became an issue) we conducted several tests on M96/7 cars to establish what was going on with different models. It was very time consuming and a labour of love to find the time but revealed very interesting results that helped us develop several products and modifications when we rebuild engines.
For our various tests we fitted temperature gauges inside various parts of the cylinder blocks and drove the cars in ambient conditions varying between 5 degrees C and 22 degrees C (over a year).
We fitted blanking covers to the radiators in different steps and covering part and full air flow and recorded the results when moving, stationary, following close behind other cars and lorries and on track.
We fitted different thermostats, different auxiliary thermostat housings and altered the coolant flow.
We found that for normal driving in town and up to 50mph one radiator was sufficient. For very fast driving in hot weather two radiators were sufficient. The only time we needed to use the third radiator (we had fitted) was on track following close behind another car and when stationary (at say lights) on a hot day after spirited driving.
From this we established that too much radiator capacity (combined with a thermostat placed at the entry to the engine and not the outlet as was more traditional) resulted in the thermostat being almost closed and the coolant flow being very slow (because the overkill amount of radiator area at the front forced the thermostat to almost close).
The engine splits the internal coolant flow so that by area about 10% goes into the cylinders and mixes back with the other 90% passing through the heads (so the differences cannot be measured unless you have internal gauges - as we did). The 10% splits off from a coolant tube at right angles (so is not best fro flow splitting).
There are therefore circumstances where the engine is at tickover - hardly any coolant is passing through the block and heat soak increases the cylinder surface temperature - thinning the oil and reducing it's ability to maintain a think film between the piston and the bore under the next imminent power run - so if a loose piece of Silicon gest stuck in between at that point - this is when damage can occur.
So we manufactured a thermostat housing for the 3rd radiator and advised owners not to rag the engine after a stop when it had been hot (and not to accelerate with too much throttle in 2nd in a tiptronic).
The 9A1 engine is similar in some ways and different in others. The M96/7 allows the cylinders to heat up more quickly as they are thin and they run with bigger piston clearances anyway. The 9A1 has smaller piston clearances and a different piston shape - that in all normal circumstances would contribute to it being a better engine (which it is). However the alloy castings near the bottom of the cylinders are all part of the block and are thick (holding the crankshaft shells) and these will take longer to heat through and allow the bottom of the block to expand.
If there had not been any stress relieving going on - that would have been OK but as the bottom of the cylinders (at one end of the crankcases) of all the engines we measured - shows shrinkage - that already reduces the piston clearance such that if the piston expands quicker than the block it may become too tight and "cold seize".
It is difficult to find a way to avoid damage resulting except to heat up the pistons more slowly (allowing time for the coolant and block to heat up and expand).
We do not have the resources to find out much more at this stage but I doubt that normal modest speeds (say up to a third throttle opening) would cause damage and that it takes about 15 minutes to warm the engine through.
In cold weather it would be better if the cars had been fitted with a radiator or air intake to the cooling system blind (to isolate a radiator and reduce cooling capacity until it was needed). Perhaps in sub zero climates (at part of the year) a cover could be fitted to one radiator beneficially).
I don't think allowing the car to stand ticking over from cold is necessary (or a good idea) probably best just to drive with restraint.
If an owners only drive is up to say 15 minutes long - I think they either should restrain their driving speeds or consider a different car - or wait until they have a longer drive to experience the performance.
Baz
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Presto (03-17-2021)
11-07-2017, 07:13 AM
#49
This thread is very interesting. As a metallurgist I find the Lokasil/Nikasil and their specific metallurgical microstructure very intruiging and a perfect example of high tech materials engineering. Even if it did not resulted in a reliable engine design. But that is a different story.
Could you elaborate on this 3rd rad thermostat housing. Is it an additional thermostat in order to 'switch off' the 3rd rad when the extra cooling capacity is not needed (i.e. cold outside temps?)
I have the 3rd radiator, also a LTT which is relocated to the outlet of the engine.
I notice with colder ambient temperature, i.e. 0°C-5°C, that upon driving and shifting to a lower gear without adding extra load or throttle (higher rpm = higher flow rate water pump) I see small dips in coolant temperature (drops around 5-6°C) after which the temperature stabilises again around its equilibrium of 81-82°C. I understand this is the thermostat adapting to the higher flow of cold water which enters the block when going to higher rpms.
Is this part of the problem when a 3rd radiator is used as you indicate in your post above?
Such as I refer to: in colder weather; coming to a standstill; the thermostat in pretty closed position due to 3rd radiator; not enough cool water is entering the engine when driving away. Or does the scenario is only of importance in hot weather and coming to a stop.
Eric
I have the 3rd radiator, also a LTT which is relocated to the outlet of the engine.
I notice with colder ambient temperature, i.e. 0°C-5°C, that upon driving and shifting to a lower gear without adding extra load or throttle (higher rpm = higher flow rate water pump) I see small dips in coolant temperature (drops around 5-6°C) after which the temperature stabilises again around its equilibrium of 81-82°C. I understand this is the thermostat adapting to the higher flow of cold water which enters the block when going to higher rpms.
Is this part of the problem when a 3rd radiator is used as you indicate in your post above?
Such as I refer to: in colder weather; coming to a standstill; the thermostat in pretty closed position due to 3rd radiator; not enough cool water is entering the engine when driving away. Or does the scenario is only of importance in hot weather and coming to a stop.
Eric
Last edited by Silk; 11-07-2017 at 09:12 AM.
11-07-2017, 07:17 AM
#50
Hi Baz
For me, the situation is reversed. I live in a warm country. Most of the year is summer..
As I mentioned, I use 5W 50 Mobile 1 (997.1 3.8 TIP S).
What is your recommendation to keep the engine?
Is it necessary to wait a few minutes before driving? Or, start the engine and drive?
Is it always recommended to start the first gear even when the engine is hot? Is this oil suitable?
Thanks again!
For me, the situation is reversed. I live in a warm country. Most of the year is summer..
As I mentioned, I use 5W 50 Mobile 1 (997.1 3.8 TIP S).
What is your recommendation to keep the engine?
Is it necessary to wait a few minutes before driving? Or, start the engine and drive?
Is it always recommended to start the first gear even when the engine is hot? Is this oil suitable?
Thanks again!
11-07-2017, 08:46 AM
#51
As you can read the 997.1 is not affected by the cold seizure as explained in the first post. So I think the 997.1 would be less prone to such a seizure. However, as with every Porsche, it is best after cold start to go and drive, warm up the engine before going hard on throttle. Warming up by idling is not ideal. By driving off short after start up and going through the lower rev-range you will allow for (more) oil splashing around in the crankcase which contributes in a faster and more uniform warming up of your engine. Also the thicker oil at cold start is forced to flow more when in higher revs then idle, better lubrication of those parts of the engine to where the oil reaches less easily.
As for cooling issues in the 996 and 997.1 as described above it is more about what to do with a fully warm up or hot engine rather then the cold start. Coming to a standstill after a hard run, the so called heat soak will result in locally higher temperatures. Therefore Baz's advise is to drive off gently in order for the water to start circulating faster and is able to take away some of the built op heat before you would floor the throttle.
In case of a Tiptronic it could be better in this circumstance to switch to 1st gear as the engine will rev faster and less force will be applied on the working side of the cilinder compared to driving off from 2nd gear.
What I do after a hard run or coming to a standstill from a higher speed (i.e. highway) is to rev up a bit the engine once every 5 or 10 seconds, i.e. 1500-2000rpm pulses, as to force some extra water flowing through the engine during stand still.
Maybe a slightly smaller pulley on the waterpump will create some extra flow when idling to provide a better cooling and prevent the so called heat-soak. However the issue of cavitating could be of concern at higher rpms.
I think the 5W50 oil is a good oil for hot climate!
I am also curious to Baz his input!
As I certainly do not want to pretend to know the answers with this reply
I am far less knowledgeable in this matter.
Eric
As for cooling issues in the 996 and 997.1 as described above it is more about what to do with a fully warm up or hot engine rather then the cold start. Coming to a standstill after a hard run, the so called heat soak will result in locally higher temperatures. Therefore Baz's advise is to drive off gently in order for the water to start circulating faster and is able to take away some of the built op heat before you would floor the throttle.
In case of a Tiptronic it could be better in this circumstance to switch to 1st gear as the engine will rev faster and less force will be applied on the working side of the cilinder compared to driving off from 2nd gear.
What I do after a hard run or coming to a standstill from a higher speed (i.e. highway) is to rev up a bit the engine once every 5 or 10 seconds, i.e. 1500-2000rpm pulses, as to force some extra water flowing through the engine during stand still.
Maybe a slightly smaller pulley on the waterpump will create some extra flow when idling to provide a better cooling and prevent the so called heat-soak. However the issue of cavitating could be of concern at higher rpms.
I think the 5W50 oil is a good oil for hot climate!
I am also curious to Baz his input!
As I certainly do not want to pretend to know the answers with this reply
I am far less knowledgeable in this matter.
Eric
Last edited by Silk; 11-07-2017 at 09:32 AM.
11-07-2017, 09:39 AM
#52
As you can read the 997.1 is not affected by the cold seizure as explained in the first post. So I think the 997.1 would be less prone to such a seizure. However, as with every Porsche, it is best after cold start to go and drive, warm up the engine before going hard on throttle. Warming up by idling is not ideal. By driving off short after start up and going through the lower rev-range you will allow for (more) oil splashing around in the crankcase which contributes in a faster and more uniform warming up of your engine. Also the thicker oil at cold start is forced to flow more when in higher revs then idle, better lubrication of those parts of the engine to where the oil reaches less easily.
As for cooling issues in the 996 and 997.1 as described above it is more about what to do with a fully warm up or hot engine rather then the cold start. Coming to a standstill after a hard run, the so called heat soak will result in locally higher temperatures. Therefore Baz's advise is to drive off gently in order for the water to start circulating faster and is able to take away some of the built op heat before you would floor the throttle.
In case of a Tiptronic it could be better in this circumstance to switch to 1st gear as the engine will rev faster and less force will be applied on the working side of the cilinder compared to driving off from 2nd gear.
What I do after a hard run or coming to a standstill from a higher speed (i.e. highway) is to rev up a bit the engine once every 5 or 10 seconds, i.e. 1500-2000rpm pulses, as to force some extra water flowing through the engine during stand still.
Maybe a slightly smaller pulley on the waterpump will create some extra flow when idling to provide a better cooling and prevent the so called heat-soak. However the issue of cavitating could be of concern at higher rpms.
I think the 5W50 oil is a good oil for hot climate!
I am also curious to Baz his input!
As I certainly do not want to pretend to know the answers with this reply
I am far less knowledgeable in this matter.
Eric
As for cooling issues in the 996 and 997.1 as described above it is more about what to do with a fully warm up or hot engine rather then the cold start. Coming to a standstill after a hard run, the so called heat soak will result in locally higher temperatures. Therefore Baz's advise is to drive off gently in order for the water to start circulating faster and is able to take away some of the built op heat before you would floor the throttle.
In case of a Tiptronic it could be better in this circumstance to switch to 1st gear as the engine will rev faster and less force will be applied on the working side of the cilinder compared to driving off from 2nd gear.
What I do after a hard run or coming to a standstill from a higher speed (i.e. highway) is to rev up a bit the engine once every 5 or 10 seconds, i.e. 1500-2000rpm pulses, as to force some extra water flowing through the engine during stand still.
Maybe a slightly smaller pulley on the waterpump will create some extra flow when idling to provide a better cooling and prevent the so called heat-soak. However the issue of cavitating could be of concern at higher rpms.
I think the 5W50 oil is a good oil for hot climate!
I am also curious to Baz his input!
As I certainly do not want to pretend to know the answers with this reply
I am far less knowledgeable in this matter.
Eric
Eric, Thanks a lot for the answer!
11-07-2017, 10:32 AM
#53
Hi Baz, another thing. I heard from a rebuilder I know that seizure of the 997.2 block occurs more often then you mention, and for different reasons (or maybe they are interrelated).
Most of those seizures are attributed to a malfunctioning of one or more injectors. They tend to fail as they get dirty very fast thereby reducing the amount of fuel injected and the fuel mist they spray. Over time when this problem gets worse there is not enough fuel spray which helps cooling the head region of the cilinder and as a result when flooring the pedal causes overheating which eventually makes the piston to seize.
This injector issue seems to be known by Porsche and has apparently been addressed during later revisions of the engine design.
Most of those seizures are attributed to a malfunctioning of one or more injectors. They tend to fail as they get dirty very fast thereby reducing the amount of fuel injected and the fuel mist they spray. Over time when this problem gets worse there is not enough fuel spray which helps cooling the head region of the cilinder and as a result when flooring the pedal causes overheating which eventually makes the piston to seize.
This injector issue seems to be known by Porsche and has apparently been addressed during later revisions of the engine design.
11-07-2017, 12:55 PM
#54
Burning Brakes
Both the 9A1 and M96/M97 owner's manual caution against letting the car warm up by idling. Now 'warm up' is not specifically defined in terms of what the target water and oil temperatures get to when warm up is complete, but they don't want that occurring in an idle session. So warm them up (there's that word again) under light loading, until oil/water reach operating temperature. That could mean 15 minutes for the oil, while driving. And it sounds like the 9A1 seizure could come on sudden like, with no tell tale engine anomalies prior to lock up. Baz calls it cold seize, and this may mean metal exchange, versus piston seized in the bore.
Lots of cold seizure technical discussions on the internet-
http://www.groupk.com/tec-seizures.htm
Lots of cold seizure technical discussions on the internet-
http://www.groupk.com/tec-seizures.htm
Last edited by Ericson38; 11-07-2017 at 01:51 PM.
11-07-2017, 01:11 PM
#55
If a 9A1 engine had siezed or we had lots of them doing it, I think by now that info would be public. A piston getting stuck in the bore is big news. I’m guessing the rod would snap too. I’d like to see proof of this, that’s all.
11-07-2017, 01:26 PM
#56
Pro
What is 'warm'? 15 mins driving in a tropical climate is different to 15 mins in the middle of Iceland in the depth of winter.
Does warm mean the temp gauge is at 12 o'clock, and the oil temp gauge at 7 o'clock or 8?
Does warm mean the temp gauge is at 12 o'clock, and the oil temp gauge at 7 o'clock or 8?
11-07-2017, 01:54 PM
#57
I've been following this thread since it started. It's been very informative.
Baz, I have a 2006 Carrera 4S X51 w/6MT. I bought it with 79,400 miles on the clock and it currently reads at 85,700.
I have no signs of bore scoring (i.e. sooty left tailpipe, etc).
The previous owner and myself have never seen any metal shavings in the oil indicating an IMS issue.
I always warm it up gently, keeping it under 3000 rpm, using the lowest gear possible, avoiding heavy load, until the oil comes up to temperature. It consumes a little oil, but well within Porsche's specs. Once it comes up to temperature I gradually increase revs before really caning it. I also avoid short drives in it.
Based on your observations on cars with a third radiator, should I look into getting a low temp thermostat installed?
Also, the car has always been getting Mobil 1 0W-40 or 5W-40. Being a resident of San Diego, should I switch to a slightly thicker oil?
Baz, I have a 2006 Carrera 4S X51 w/6MT. I bought it with 79,400 miles on the clock and it currently reads at 85,700.
I have no signs of bore scoring (i.e. sooty left tailpipe, etc).
The previous owner and myself have never seen any metal shavings in the oil indicating an IMS issue.
I always warm it up gently, keeping it under 3000 rpm, using the lowest gear possible, avoiding heavy load, until the oil comes up to temperature. It consumes a little oil, but well within Porsche's specs. Once it comes up to temperature I gradually increase revs before really caning it. I also avoid short drives in it.
Based on your observations on cars with a third radiator, should I look into getting a low temp thermostat installed?
Also, the car has always been getting Mobil 1 0W-40 or 5W-40. Being a resident of San Diego, should I switch to a slightly thicker oil?
11-07-2017, 09:16 PM
#58
shawn_nj This is a bigger problem than it seems at first. As engines produce more power (as they have done in this Porsche range over the previous 2 decades) the amount of heat generated when flat out increases and so the cars need more cooling capacity built into them so they survive when owners are exploiting their full potential.
Baz
Last edited by shawn_nj; 11-07-2017 at 09:32 PM.
11-07-2017, 10:36 PM
#59
Here's what I do to prevent scoring. It also works for irritable bowel syndrome.
I only drive on Mondays between 1127 am and 248 pm and Thursdays from 558 am to 730 am. To warm it up, I shift at 2250 in first, 2100 in second, 3300 in third, I skip 4th, 3200 in 5th, and 2400 in 6th. Unless it's colder than 56 degrees. Then I reduce RPMs in all gears by 21%.
Once warm, I only drive in reverse and only make left turns.
When I get home, I change the oil. I use 5.7W34 oil from Quebec. Leave the cap open for an hour to let it breath before filling.
Finally, on the off days I roll the windows half down.
Hope that helps.
I only drive on Mondays between 1127 am and 248 pm and Thursdays from 558 am to 730 am. To warm it up, I shift at 2250 in first, 2100 in second, 3300 in third, I skip 4th, 3200 in 5th, and 2400 in 6th. Unless it's colder than 56 degrees. Then I reduce RPMs in all gears by 21%.
Once warm, I only drive in reverse and only make left turns.
When I get home, I change the oil. I use 5.7W34 oil from Quebec. Leave the cap open for an hour to let it breath before filling.
Finally, on the off days I roll the windows half down.
Hope that helps.
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987.3 (07-01-2020)
11-08-2017, 05:32 AM
#60
User
Thread Starter
Lots to answer - forgive me for being brief.
For warm up I advise start and go but not with high revs and not a lot of throttle - increasing both gradually as temperatures climb.
Silk - Thermostats control flow - but the radiator area available is a complicated design issue. When the engine is cold the thermostat is shut to allow the coolant to stay in the heat source (the engine) longer - so it heats up quicker. As the thermostat slowly opens the flow increases.
If the radiator area is too large the thermostat has to remain almost shut because the excessive radiator area has cooled the coolant too much and it therefore flows through the engine slower and with less force to swirl around touching less of the heat source areas. If it flows slower it picks up more heat while in the engine so the outlet temperature is higher than if it flowed more quickly (which we want to avoid).
So ideally you would only need a 3rd radiator when it is very hot - the driver is using a lot of throttle and/or the airflow is restricted.
A thermostat set at a slightly higher temperature than the main thermostat and placed in the flow to the 3rd radiator, effectively makes it available only when the other two radiators can no longer cool the engine and the coolant temperature is rising too high - when it slowly opens and introduce more radiator area consistent with demand.
f911 - yes start and go.
Silk - Yes there are 2 completely different scenarios for 997.1 and 997.2 regarding scoring/seizing problems.
997.1 scoring due to silicon particle loss and piston coating failure and 997.2 (the ones we have come into contact with) bores shrinking in diameter near the bottom, reducing the piston clearance until the piston expansion is greater and causes a classic "cold seize".
I agree it is a good idea to blip the throttle when stationary after a hot run.
Thank you for the information about injector clogging. We have not experienced any of this casing seizures.
All the 9A1 engines we have been involved in had reduced bore diameters and piston clearances at one end of the engine near the bottom of the cylinder causing cold seizures. All had occurred on cold days in cold climates after reduced warm-up times. None showed any signs of excessive piston crown temperatures or detonation.
Those that we repaired were fitted with the same injectors and have since worked perfectly. This is an exert from a typical reply received a few weeks ago from one such customer.
Hi Baz - my car is still running perfectly and hasn't had any issue since the repair. I have added a little oil - but nothing extraordinary and I do drive it hard once it is warm so little surprise there. So this is just a short note to confirm all is great after lots of use and some hard driving and thanks again to you and your team for making my car great again.
M k
Could it be that there are 2 faults arising or that injector clogging heated the pistons up more quickly from cold (when maximum flow is required to richen the mixture) and that the bores had indeed closed up and the weakened cold fuel mixture raised the piston temperature and expansion even more quickly before the cylinder bores had expanded sufficiently?
Of course - after a rebuild with a new block or new engine - the bores to piston clearance would not be so tight - so with old or new injectors would not cause a problem. Or could it be that the diagnosis saw seized pistons - saw what looked like clogged injectors and drew the wrong conclusion - by failing to investigate (or be reluctant to reveal) the true cause that we found - and in fact were the same?
Our seizures were all in the lower half of the piston and it is more usual to see failures nearer the top when it is caused by weak mixtures. They were also nearer the bottom of the cylinder bore and that was because that was where the smallest diameters were.
It could therefore be that the injector clogging was partly influential but that the real fault was the shrinking bore clearance - or it could be that they were nothing to do with it and miss-diagnosed.
Erikson 38 I agree to warm up with progressive driving and yes I was referring to metal exchange cold seizures.
DC911S I am not prepared to waste time discussing the implication that we are either incompetent or lying - you want proof - come to us and I will show it to you.
318 Touring - don't drive flat out until both coolant and oil have reached the normal highest running temperature when previously driving fast in similar ambient conditions and then still build up over a minute or two.
srcu I suggest moving up one grad now your engine is getting older - otherwise you seem to be doing everything right - carry on.
shawn_nj Sounds all good to me.
casm3os - thanks for the light hearted entertainment - while we discuss a serious potential problem - I agree it can become too heavy at times - but in case you were being sarcastic - we are trying to help. You will no doubt accept that such information is not directed to those who already do the right things - but those who don't to try and help then avoid unnecessary costs.
As an analogy - it might help prevent health problems to explain the potential problems resulting from smoking to smokers and it might help those that have given up to reinforce the benefits of their change to better habits - and those that anyway adopted good habits to keep up the good work - but I think we can all agree that those that don't know about the potential problems and smoke could do without humorous posts suggesting they should double their habit and move on to stronger cigarettes, take larger drags and hold it in as long as possible.
We all know about the dangers of smoking because it has been publicised so much but this is the first time this issue has come to light. I think it took a long time when the dangers of cigarette smoking was first identified - before it was taken seriously.
When the M96/7 engines first failed they were either still under warranty or extended warranty and it took until the prices dropped and typical owners were not covered or could not afford a new engine - before the independent sector became more aware of a problem. Those who previously worked in Main Agents have confirmed that several engines were replaced before it became wider knowledge and of course the failures were related to age and mileage as well so were less likely to occur for some years.
This 9A1 problem that we have found consistently in the engines we have dealt with are all the same and would take many years to develop - beyond the age when many have Main Agent replacement cover - hence the inevitability that it only surfaces now and that we cannot determine the seriousness yet (or lack of it) but in the meantime there seems no harm to reinforce to owners the need to be patient until engines are fully warmed up before enjoying the full performance (as anyway stipulated in the manual and all good manufacturers advice).
Baz
For warm up I advise start and go but not with high revs and not a lot of throttle - increasing both gradually as temperatures climb.
Silk - Thermostats control flow - but the radiator area available is a complicated design issue. When the engine is cold the thermostat is shut to allow the coolant to stay in the heat source (the engine) longer - so it heats up quicker. As the thermostat slowly opens the flow increases.
If the radiator area is too large the thermostat has to remain almost shut because the excessive radiator area has cooled the coolant too much and it therefore flows through the engine slower and with less force to swirl around touching less of the heat source areas. If it flows slower it picks up more heat while in the engine so the outlet temperature is higher than if it flowed more quickly (which we want to avoid).
So ideally you would only need a 3rd radiator when it is very hot - the driver is using a lot of throttle and/or the airflow is restricted.
A thermostat set at a slightly higher temperature than the main thermostat and placed in the flow to the 3rd radiator, effectively makes it available only when the other two radiators can no longer cool the engine and the coolant temperature is rising too high - when it slowly opens and introduce more radiator area consistent with demand.
f911 - yes start and go.
Silk - Yes there are 2 completely different scenarios for 997.1 and 997.2 regarding scoring/seizing problems.
997.1 scoring due to silicon particle loss and piston coating failure and 997.2 (the ones we have come into contact with) bores shrinking in diameter near the bottom, reducing the piston clearance until the piston expansion is greater and causes a classic "cold seize".
I agree it is a good idea to blip the throttle when stationary after a hot run.
Thank you for the information about injector clogging. We have not experienced any of this casing seizures.
All the 9A1 engines we have been involved in had reduced bore diameters and piston clearances at one end of the engine near the bottom of the cylinder causing cold seizures. All had occurred on cold days in cold climates after reduced warm-up times. None showed any signs of excessive piston crown temperatures or detonation.
Those that we repaired were fitted with the same injectors and have since worked perfectly. This is an exert from a typical reply received a few weeks ago from one such customer.
Hi Baz - my car is still running perfectly and hasn't had any issue since the repair. I have added a little oil - but nothing extraordinary and I do drive it hard once it is warm so little surprise there. So this is just a short note to confirm all is great after lots of use and some hard driving and thanks again to you and your team for making my car great again.
M k
Could it be that there are 2 faults arising or that injector clogging heated the pistons up more quickly from cold (when maximum flow is required to richen the mixture) and that the bores had indeed closed up and the weakened cold fuel mixture raised the piston temperature and expansion even more quickly before the cylinder bores had expanded sufficiently?
Of course - after a rebuild with a new block or new engine - the bores to piston clearance would not be so tight - so with old or new injectors would not cause a problem. Or could it be that the diagnosis saw seized pistons - saw what looked like clogged injectors and drew the wrong conclusion - by failing to investigate (or be reluctant to reveal) the true cause that we found - and in fact were the same?
Our seizures were all in the lower half of the piston and it is more usual to see failures nearer the top when it is caused by weak mixtures. They were also nearer the bottom of the cylinder bore and that was because that was where the smallest diameters were.
It could therefore be that the injector clogging was partly influential but that the real fault was the shrinking bore clearance - or it could be that they were nothing to do with it and miss-diagnosed.
Erikson 38 I agree to warm up with progressive driving and yes I was referring to metal exchange cold seizures.
DC911S I am not prepared to waste time discussing the implication that we are either incompetent or lying - you want proof - come to us and I will show it to you.
318 Touring - don't drive flat out until both coolant and oil have reached the normal highest running temperature when previously driving fast in similar ambient conditions and then still build up over a minute or two.
srcu I suggest moving up one grad now your engine is getting older - otherwise you seem to be doing everything right - carry on.
shawn_nj Sounds all good to me.
casm3os - thanks for the light hearted entertainment - while we discuss a serious potential problem - I agree it can become too heavy at times - but in case you were being sarcastic - we are trying to help. You will no doubt accept that such information is not directed to those who already do the right things - but those who don't to try and help then avoid unnecessary costs.
As an analogy - it might help prevent health problems to explain the potential problems resulting from smoking to smokers and it might help those that have given up to reinforce the benefits of their change to better habits - and those that anyway adopted good habits to keep up the good work - but I think we can all agree that those that don't know about the potential problems and smoke could do without humorous posts suggesting they should double their habit and move on to stronger cigarettes, take larger drags and hold it in as long as possible.
We all know about the dangers of smoking because it has been publicised so much but this is the first time this issue has come to light. I think it took a long time when the dangers of cigarette smoking was first identified - before it was taken seriously.
When the M96/7 engines first failed they were either still under warranty or extended warranty and it took until the prices dropped and typical owners were not covered or could not afford a new engine - before the independent sector became more aware of a problem. Those who previously worked in Main Agents have confirmed that several engines were replaced before it became wider knowledge and of course the failures were related to age and mileage as well so were less likely to occur for some years.
This 9A1 problem that we have found consistently in the engines we have dealt with are all the same and would take many years to develop - beyond the age when many have Main Agent replacement cover - hence the inevitability that it only surfaces now and that we cannot determine the seriousness yet (or lack of it) but in the meantime there seems no harm to reinforce to owners the need to be patient until engines are fully warmed up before enjoying the full performance (as anyway stipulated in the manual and all good manufacturers advice).
Baz
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Presto (03-17-2021)