The Elephant in the Room - #2 Rod Bearing Failures
03-08-2013, 11:24 PM
#46
03-08-2013, 11:51 PM
#47
Rennlist Member
Thread Starter
03-09-2013, 01:31 PM
#48
More post from the 928 folks, tons of info on this subject
Dry sump setup, Second post shows mod to 2/6 oil channel
https://rennlist.com/forums/10062225-post40.html
https://rennlist.com/forums/10062733-post50.html
A solution to this problem, street and race.
https://rennlist.com/forums/10064688-post73.html
https://rennlist.com/forums/10065306-post82.html
https://rennlist.com/forums/10065435-post83.html
https://rennlist.com/forums/10067698-post102.html
https://rennlist.com/forums/10068706-post109.html
Dry sump setup, Second post shows mod to 2/6 oil channel
https://rennlist.com/forums/10062225-post40.html
https://rennlist.com/forums/10062733-post50.html
A solution to this problem, street and race.
https://rennlist.com/forums/10064688-post73.html
https://rennlist.com/forums/10065306-post82.html
https://rennlist.com/forums/10065435-post83.html
https://rennlist.com/forums/10067698-post102.html
https://rennlist.com/forums/10068706-post109.html
03-09-2013, 02:43 PM
#49
Burning Brakes
Some very interesting finds in these threads. I might make a custom windage tray/scraper arrangement for my engine. I want to change the location of the upstroke scraper from where IJ has it, as in his location the return chutes actually dump the oil from the head on top of the scraper, splashing it onto the crank and potentially worsening the problem of aeration.
03-09-2013, 06:05 PM
#50
Burning Brakes
Some observations of the 944 block.
I am no expert, but I have an extra block to study and I have been trying to understand this problem for some time.
1. The 928 crowd seem to have problems with oil filling up the heads. Some believe this is due to a pressure differential between the crank case and the heads. I don't know the 928 head design but they seem to be vented. Since the 944 8V head is not vented we should always have positive pressure in the heads given how much oil is being pushed out there. In our case i believe the extremely badly cast return chutes from the head may be to blame. They look big but they are actually only 8mm in dia at the smallest point. If possible they should be enlarged to allow the oil to return to the pan as quickly as possible. This one has been enlarged by about 25%, but the real restriction is much higher up in the actual block where the chute passes the oil path going to the mains.
2. the crank case is extremely limited in space. The pistons are pushing a lot of air up and down and this air cannot easily move between cylinders. The air flowing between cylinders 1-2 and 3-4 has to push along the oil pan to move and will whip up whatever oil is in the pan and fling it onto the crank where it will be instantly aerated.
3. The air flowing from under the pistons as described above will push the oil returning from the head directly onto the crank. This means that we are robbed of the longest return path of the oil, where the potential for air separation is the greatest!
4. One partial solution to the massive windage problems described above is to machine these windage ports in the block, as I have done in the pics below. LR does this and they copied it from the 2.7 and 3L block designs which tells us that Porsche knew about these problems.
5. The available crank scrapers may increase the problem as they block the return paths of the oil from the head.
If the scraper could be mounted higher in the crank case it would be above the oil returning from the head.
A possible solution would be to construct a scraper/windage tray á la this. Bear in mind this is just a quick mock up I did this evening to see what may be done. It may not be ideal for longevity/safety, and ports would be have to be constructed in the bridges to allow air to flow back and forth between cylinders.
Another solution may be to extend the return chutes all the way to the oil pan and have them exit below a windage tray so that they oil from the head may remain as bubble-free as possible on its way to the sump.
Finally one could block the return ports from the head and engineer an external return path from the head along the lines of the drainage line from the turbo.
1. The 928 crowd seem to have problems with oil filling up the heads. Some believe this is due to a pressure differential between the crank case and the heads. I don't know the 928 head design but they seem to be vented. Since the 944 8V head is not vented we should always have positive pressure in the heads given how much oil is being pushed out there. In our case i believe the extremely badly cast return chutes from the head may be to blame. They look big but they are actually only 8mm in dia at the smallest point. If possible they should be enlarged to allow the oil to return to the pan as quickly as possible. This one has been enlarged by about 25%, but the real restriction is much higher up in the actual block where the chute passes the oil path going to the mains.
2. the crank case is extremely limited in space. The pistons are pushing a lot of air up and down and this air cannot easily move between cylinders. The air flowing between cylinders 1-2 and 3-4 has to push along the oil pan to move and will whip up whatever oil is in the pan and fling it onto the crank where it will be instantly aerated.
3. The air flowing from under the pistons as described above will push the oil returning from the head directly onto the crank. This means that we are robbed of the longest return path of the oil, where the potential for air separation is the greatest!
4. One partial solution to the massive windage problems described above is to machine these windage ports in the block, as I have done in the pics below. LR does this and they copied it from the 2.7 and 3L block designs which tells us that Porsche knew about these problems.
5. The available crank scrapers may increase the problem as they block the return paths of the oil from the head.
If the scraper could be mounted higher in the crank case it would be above the oil returning from the head.
A possible solution would be to construct a scraper/windage tray á la this. Bear in mind this is just a quick mock up I did this evening to see what may be done. It may not be ideal for longevity/safety, and ports would be have to be constructed in the bridges to allow air to flow back and forth between cylinders.
Another solution may be to extend the return chutes all the way to the oil pan and have them exit below a windage tray so that they oil from the head may remain as bubble-free as possible on its way to the sump.
Finally one could block the return ports from the head and engineer an external return path from the head along the lines of the drainage line from the turbo.
Last edited by bebbetufs; 03-16-2013 at 04:35 AM.
03-10-2013, 09:59 AM
#51
This is a great thead.. My take
I think it's all about clean, cool, foam free oil, on my 924S that I tracked, I ran a kiss oil cooler on the Drivers side, with long oil lines to a 951 oil filter housing, I ran that car hard, over redline A LOT, running 20w50 VR1 oil, and always ran a little over the full line, I think the Longer oil lines gave the oil time to Defoam, and the bigger cooler was a huge help, Plus the setup added about 2 extra qrts to the system, never ran into any bearing problems on that engine.. So I think if you just increase capacity and add a Long turbulence free oil path, like The oil lines I ran to the drivers side, It gives the oil time to defoam and collect before it's time to go into the engine.... But I will say you guys have some great Ideas that may just fix the problem
I think it's all about clean, cool, foam free oil, on my 924S that I tracked, I ran a kiss oil cooler on the Drivers side, with long oil lines to a 951 oil filter housing, I ran that car hard, over redline A LOT, running 20w50 VR1 oil, and always ran a little over the full line, I think the Longer oil lines gave the oil time to Defoam, and the bigger cooler was a huge help, Plus the setup added about 2 extra qrts to the system, never ran into any bearing problems on that engine.. So I think if you just increase capacity and add a Long turbulence free oil path, like The oil lines I ran to the drivers side, It gives the oil time to defoam and collect before it's time to go into the engine.... But I will say you guys have some great Ideas that may just fix the problem
03-10-2013, 08:36 PM
#52
Drifting
Something to consider when changing your oil on a high mileage car. At your next oil change, have it tested for any contanimants. Take a sample of your oil and have it checked for contamination. You will get a report of what's in your oil. I think many of the modded motors have some gasket seep, and if metals are present, you'll know from these reports. I have this done on my Diesel Cat turbo pusher motorhome. I think I pay about $50 bucks for the report, and it's paid for itself when I had a head gasket seeping coolant into the oil. Changed out the gaskets, and the following report showed everything within normal ranges.
03-13-2013, 07:04 PM
#53
Administrator - "Tyson"
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Here is an interesting post from the regular 944 forum:
https://rennlist.com/forums/10296017-post18.html
https://rennlist.com/forums/10296017-post18.html
The information I provide is based on facts. We run 20-25 944's racing and in our driving school. Our average 944 logs in over 100 hours between rod bearing replacement with some cars running over 140 hours.
In December we ran a 1986 Spec 944 in the 25 hours of Thunderhill, finishing after 25 hours of racing and 7 hours of practice with a total of 32 hours on the engine and drive train. We encountered 0 engine or drivetrain problems. Team Raptor. We will be returning this December with a 944 and 924S taking advantage of the NASA rules with more HP and much lighter cars.
The reason #2 rod bearing is the first bearing starved for oil is due to the oil supply to both balance shafts is supplied where #2 rod bearing is supplied oil from the pump.
The causes of the starvation are due from the following:
#1 Driver error, over-revving the engine on up shifting and worse using the engine as a brake downshifting, over-revving the engine. This translates to the transaxle, driveshaft, axles, etc.
#2 Driver error, driving the engine too hard when the oil and water are not up to operating temp. Usually a slow and destructive method damaging rod bearings.
#3 Driver error, failure to properly maintain. Change oil, radiator, water pump, engine overheats.
#4 Distributor rotor failure, usually arching across the top burning out the end of the rotor. The end result is misfiring hammering the pistons, rods and rod bearings.
#5 Oil pump does not properly pump oil due to wear, expansion and contraction of the steel gears and cover to the aluminum housing. This is easily seen when starting a cold engine and the oil takes time to gain pressure or will not gain pressure when cranked unless started. This condition is not catastrophic, it can contribute to bearing failure.
#6 High bank left hand or even right hand corners at high RPM's, the oil pressure gauge will move up and down or lower for a few seconds.
#7 Oil pick up tube cracked and or rubber seal hard and not properly sealing causing air to be sucked into the system under a load.
#8 Main bearings worn out starving the rod bearings.
Street or race the damage can be avoided. All of our cars have hour meters installed and rev limiters, both factory and MSD.
The majority of 944 owners are second, third, fourth, etc. owners. We have no idea how the car was maintained or driven.
All of our 944's have the rod bearings replaced, oil pick up tubes inspected and the 0 ring replaced. All heads are removed, cylinder walls inspected, a rebuilt head and all new gaskets installed. Radiators and hoses are tested and replaced as necessary.
We have installed several sets of coated rod bearings and found little or no wear after as much as 140 plus hours in a race 944. #2 rod bearing showed the coating worn off. To reduce #2 wear we eliminate the balance shaft belts, pulleys and gears. To eliminate the excessive wear on #2, removal and sealing off the balance shaft oil holes is required. This is a process we perform when using a dry sump system allowing a max RPM in the 8-8500 range.
There are hundreds of items we have discovered needing repair, replacement, updating, back dating and at a minimum inspection for possible damage in the 14 years we have been building and racing 944's and 924S's. Every year the 944 was produced there were changes made.
In December we ran a 1986 Spec 944 in the 25 hours of Thunderhill, finishing after 25 hours of racing and 7 hours of practice with a total of 32 hours on the engine and drive train. We encountered 0 engine or drivetrain problems. Team Raptor. We will be returning this December with a 944 and 924S taking advantage of the NASA rules with more HP and much lighter cars.
The reason #2 rod bearing is the first bearing starved for oil is due to the oil supply to both balance shafts is supplied where #2 rod bearing is supplied oil from the pump.
The causes of the starvation are due from the following:
#1 Driver error, over-revving the engine on up shifting and worse using the engine as a brake downshifting, over-revving the engine. This translates to the transaxle, driveshaft, axles, etc.
#2 Driver error, driving the engine too hard when the oil and water are not up to operating temp. Usually a slow and destructive method damaging rod bearings.
#3 Driver error, failure to properly maintain. Change oil, radiator, water pump, engine overheats.
#4 Distributor rotor failure, usually arching across the top burning out the end of the rotor. The end result is misfiring hammering the pistons, rods and rod bearings.
#5 Oil pump does not properly pump oil due to wear, expansion and contraction of the steel gears and cover to the aluminum housing. This is easily seen when starting a cold engine and the oil takes time to gain pressure or will not gain pressure when cranked unless started. This condition is not catastrophic, it can contribute to bearing failure.
#6 High bank left hand or even right hand corners at high RPM's, the oil pressure gauge will move up and down or lower for a few seconds.
#7 Oil pick up tube cracked and or rubber seal hard and not properly sealing causing air to be sucked into the system under a load.
#8 Main bearings worn out starving the rod bearings.
Street or race the damage can be avoided. All of our cars have hour meters installed and rev limiters, both factory and MSD.
The majority of 944 owners are second, third, fourth, etc. owners. We have no idea how the car was maintained or driven.
All of our 944's have the rod bearings replaced, oil pick up tubes inspected and the 0 ring replaced. All heads are removed, cylinder walls inspected, a rebuilt head and all new gaskets installed. Radiators and hoses are tested and replaced as necessary.
We have installed several sets of coated rod bearings and found little or no wear after as much as 140 plus hours in a race 944. #2 rod bearing showed the coating worn off. To reduce #2 wear we eliminate the balance shaft belts, pulleys and gears. To eliminate the excessive wear on #2, removal and sealing off the balance shaft oil holes is required. This is a process we perform when using a dry sump system allowing a max RPM in the 8-8500 range.
There are hundreds of items we have discovered needing repair, replacement, updating, back dating and at a minimum inspection for possible damage in the 14 years we have been building and racing 944's and 924S's. Every year the 944 was produced there were changes made.
03-13-2013, 07:27 PM
#54
Rennlist Member
Thread Starter
I do not think I completely agree with this post. I do believe you can manage the issue to some degree and that is the point of this thread but I still believe there is a fundamental underlying problem. Too many documented failures.
03-13-2013, 09:12 PM
#55
Rainman
Rennlist Member
Rennlist Member
This might be extreme, but what if you measured the height of the oil in the pan when full and warm, then made a baffle at that height that covered the entire sump and encased the pickup? With a full baffle, the oil couldn't slosh from side to side and the only way out would be through the pickup tube.
03-14-2013, 07:16 PM
#56
Burning Brakes
Completely agree. I am no expert, but I have been reading up on oil pan designs used in racing and from what I can see there seem to be some flaws in our pan that could be improved quite easily and potentially reduce some of the foaming. I wonder why there are no aftermarket pans available.
03-14-2013, 09:29 PM
#57
I was reading the info on LR site, about the Windage ports that are in the 2.7 and 3.0 engines, very interesting stuff, I thinks it's totally awesome that almost every year of the 944 something was changed, wish I had all the notes/research those German engineers had
03-15-2013, 04:32 AM
#58
When I read about all the people running low grade oil and stock oil cooler on track days, I'm not surprised that engines blow up. With Brad Pen 20-50 oil and stock oil cooler on a 50f day, I ran 5-6 laps before the oil temperature got to high. This was on a completely stock engine.
03-15-2013, 05:26 PM
#60
Rennlist Member
