Coolant running through AOS
05-13-2010, 04:15 PM
#16
Race Director
Not all flat engines (including Porsche engines -- air cooled anyhow) emit smoke upon startup.
This suggests the path the oil is following to get into the cylinders is not via past the pistons/rings instead is coming from the oil deposited on the intake manifold walls by the vapor leaving the AOS and directed to the intake manifold. (The valves are not submerged in oil and thus oil not seeping past the valve stem seals/guides.)
Thus there are things one can do to reduce the chances of oil smoke upon startup. Run the oil level not too low not too high. Run the right kind of oil. Try to keep the oil reasonably fresh.
Avoid short trips. In some cases this an impossibility but the effects of short trips can be mitigated by more frequent oil/filter services but to most people suggesting short trips/little usage is harder on oil is a hard sell. They just don't buy it.
Give the engine a chance to shed oil from its moving parts and to evacuate oil from under the camshaft covers after a run by giving the engine a moment or two to idle before shutting the engine off.
Potentially a change in oil brand may make the oil smoke situation better (or worse) but as long as one is running a good brand of oil that's the most important thing.
By doing the above one should have the frequency of engine smoking upon start up down to its minimum. Prolonged smoking after cold or warm or hot starts, smoking at other times, or any other untoward engine behavior with smoking is cause for concern and needs investigating.
Sincerely,
Macster.
05-13-2010, 09:44 PM
#17
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Macster,
Wow, what a comprehensive answer! You made my day, thank you!
Let us focus on the two main issues:
1) OIL:
2) COOLANT:
I think you are absolutely spot-on and the answer may be laying on the AOS. Let us imagine the following scenario:
1) There is an internal small coolant leak to the crankcase which may only appear when engine/cooling system is hot or when the engine is at higher RPM's;
2) Oil which is now being contaminated with coolant is more prone to aeration and increases oil vapor content of crankcase fumes which overwhelm the AOS and thus send lots of oil vapor to intake manifold;
3) Exhaust smoke upon every cold start-up as a result.
If you can follow my reasonning you will see that i'm trying to establish a relationship between the smoke upon start-up (OIL) and a COOLANT leak, via AOS. (It was the reason for this thread's title, although from a different perspective.) Just look at this situation (posts #30, #33 and #37).
1)Is this likely to be happening on my car?
2)Wouldn't explain it all?
3)Would i, necessarily, see coolant on oil(which is not the case)?
PS:
Yes, the light comes on when i turn on the key and go off when i start the engine.
Wow, what a comprehensive answer! You made my day, thank you!
Let us focus on the two main issues:
1) OIL:
Let me digress and cover this more thoroughly: Overfilled oil or old oil which is contaminated with water/unburned fuel which makes it more prone to aeration and increases oil vapor content of crankcase fumes. These fumes can overwhelm an AOS and thus send lots of oil vapor to intake manifold and this can result in smoking upon startup maybe every engine start. It doesn't help that you have apparently not driven the car much. Short trips, idling, all help to load the oil with water/unburned fuel.
This suggests the path the oil is following to get into the cylinders is not via past the pistons/rings instead is coming from the oil deposited on the intake manifold walls by the vapor leaving the AOS and directed to the intake manifold. (The valves are not submerged in oil and thus oil not seeping past the valve stem seals/guides.)
2) COOLANT:
I think you are absolutely spot-on and the answer may be laying on the AOS. Let us imagine the following scenario:
1) There is an internal small coolant leak to the crankcase which may only appear when engine/cooling system is hot or when the engine is at higher RPM's;
2) Oil which is now being contaminated with coolant is more prone to aeration and increases oil vapor content of crankcase fumes which overwhelm the AOS and thus send lots of oil vapor to intake manifold;
3) Exhaust smoke upon every cold start-up as a result.
If you can follow my reasonning you will see that i'm trying to establish a relationship between the smoke upon start-up (OIL) and a COOLANT leak, via AOS. (It was the reason for this thread's title, although from a different perspective.) Just look at this situation (posts #30, #33 and #37).
1)Is this likely to be happening on my car?
2)Wouldn't explain it all?
3)Would i, necessarily, see coolant on oil(which is not the case)?
PS:
Yes, the light comes on when i turn on the key and go off when i start the engine.
05-14-2010, 03:49 AM
#18
Race Director
Macster,
Wow, what a comprehensive answer! You made my day, thank you!
Let us focus on the two main issues:
1) OIL:
2) COOLANT:
I think you are absolutely spot-on and the answer may be laying on the AOS. Let us imagine the following scenario:
1) There is an internal small coolant leak to the crankcase which may only appear when engine/cooling system is hot or when the engine is at higher RPM's;
2) Oil which is now being contaminated with coolant is more prone to aeration and increases oil vapor content of crankcase fumes which overwhelm the AOS and thus send lots of oil vapor to intake manifold;
3) Exhaust smoke upon every cold start-up as a result.
If you can follow my reasonning you will see that i'm trying to establish a relationship between the smoke upon start-up (OIL) and a COOLANT leak, via AOS. (It was the reason for this thread's title, although from a different perspective.) Just look at this situation (posts #30, #33 and #37).
1)Is this likely to be happening on my car?
2)Wouldn't explain it all?
3)Would i, necessarily, see coolant on oil(which is not the case)?
PS:
Yes, the light comes on when i turn on the key and go off when i start the engine.
Wow, what a comprehensive answer! You made my day, thank you!
Let us focus on the two main issues:
1) OIL:
2) COOLANT:
I think you are absolutely spot-on and the answer may be laying on the AOS. Let us imagine the following scenario:
1) There is an internal small coolant leak to the crankcase which may only appear when engine/cooling system is hot or when the engine is at higher RPM's;
2) Oil which is now being contaminated with coolant is more prone to aeration and increases oil vapor content of crankcase fumes which overwhelm the AOS and thus send lots of oil vapor to intake manifold;
3) Exhaust smoke upon every cold start-up as a result.
If you can follow my reasonning you will see that i'm trying to establish a relationship between the smoke upon start-up (OIL) and a COOLANT leak, via AOS. (It was the reason for this thread's title, although from a different perspective.) Just look at this situation (posts #30, #33 and #37).
1)Is this likely to be happening on my car?
2)Wouldn't explain it all?
3)Would i, necessarily, see coolant on oil(which is not the case)?
PS:
Yes, the light comes on when i turn on the key and go off when i start the engine.
Generally you want to run the engine a while, shut it off, remove the oil filter housing and dump some oil into a clean bottle, the refit the housing, top up the oil.
If close by swing by the shop and and pick up a sample bottle.
If any antifreeze chemicals are found in the oil you know engine has a coolant leak, intermix problem. AOS is as good as anything to suspect cause these have a habit of going bad though causing an intermix problem is not a problem I've come across.
However, if the AOS has a coolant passage in it, this is certainly a place for a leak to develop.
If AOS is the source of the intermix problem then after you replace the AOS and the oil contaminated with the coolant the smoking upon startup should probably diminish. First no more intermix problem and second the new AOS is probably more efficient at removing oil vapor from crankcase fumes *befure* these fumes make it to the instake manifold.
If the analysis finds no evidence of anti-freeze in the oil then there is no intermix problem.
There still may be a coolant leak, but the coolant is not leaking into the engine.
One of my cars -- not a Porsche -- developed a coolant leak. Next day after a spirited run from San Jose CA to Salt Lake City Utah (during said run I collected a $170 speeding ticket...) the next morning when I went to the car on the motel parking lot I finally spotted a small puddle of coolant under radiator at front of the car. Took it to a local dealer. Service found the leak source after a long look. A tiny pinhole was in the radiator. The coolant only leaked out after hot engine shut off and pressure increased. The tech found the leak by noting a light colored stain on the darker radiator material. Fortunately, the leak was on the back side of the radiator -- the side facing the engine -- and out in the open and not buried in the folds of the radiator fins.
If coolant level low, low enough (and I don't know how low this is) the coolant warning light should come on. If the light comes on when the key turned to on and yet goes off when the engine started and the coolant level is below the sensor the sensor is bad would have to be my WAG.
Identify there is a coolant leak problem. If there is then locate the leak and fix the cause. Then worry about the smoking upon startup.
Note if you find the leak is not from the AOS and after the leak fixed and the smoking continues and there are any other untoward engine behavior the AOS could very well be bad -- just not leaking coolant -- and needs to be replaced.
Sincerely,
Macster.
05-14-2010, 08:45 AM
#19
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Macster,
At this point, I just want to eliminate the possibility of a coolant leak into the engine which could cause AOS overwhelming and hence somoke upon cold start-up. The following is what I know so far:
1) There's no visual evidence of coolant in the oil;
2) There's no visual evidence of oil in the coolant;
3) There's no evidence of combustion gases going into the coolant.
How do I know:
1) The oil was changed and no milkshake;
2)The coolant wasn't changed but its colour on a sample that came off when the filler cap was opened with a warm engine is a 'clean' pink;
3) I opened up the filler cap and started-up the engine, no bubbling or rised coolant level was observed .
Now, my doubts:
1) Is it sufficient to do a visual inspection, or I may need an oil analysis(as you state)?
2) Is the coolant sample from the filler neck good enough?
3) Should I have opened the filler cap only after the engine was started-up to first rise the pressure and then look for bubbles or 'spitted' coolant from the filler neck ?
4) How is the pressure test done in a engine/cooling system hot?
5) What else do I need to ask, besides an oil analysis, to make sure that my engine has no internal coolant leak?
At this point, I just want to eliminate the possibility of a coolant leak into the engine which could cause AOS overwhelming and hence somoke upon cold start-up. The following is what I know so far:
1) There's no visual evidence of coolant in the oil;
2) There's no visual evidence of oil in the coolant;
3) There's no evidence of combustion gases going into the coolant.
How do I know:
1) The oil was changed and no milkshake;
2)The coolant wasn't changed but its colour on a sample that came off when the filler cap was opened with a warm engine is a 'clean' pink;
3) I opened up the filler cap and started-up the engine, no bubbling or rised coolant level was observed .
Now, my doubts:
1) Is it sufficient to do a visual inspection, or I may need an oil analysis(as you state)?
2) Is the coolant sample from the filler neck good enough?
3) Should I have opened the filler cap only after the engine was started-up to first rise the pressure and then look for bubbles or 'spitted' coolant from the filler neck ?
4) How is the pressure test done in a engine/cooling system hot?
5) What else do I need to ask, besides an oil analysis, to make sure that my engine has no internal coolant leak?
05-14-2010, 01:21 PM
#20
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Macster,
Let me just say this, with my car's symptoms in the event of an internal coolant leak (into the engine) the smoke upon start-up can ONLY be due to the two causes illustrated on these two examples:
1)«It is very very unlikely you will loos it throught the exhaust because it is always under pressure. (...) then loosing it into the cylinder is almost a unlikely because the cylinder is always under pressure. Most likely it is pressurizing the cooling system and blowing the coolant out the tube. Water pump then oil cooler, Good luck.» (post #26)
[U]«I had one that would fill the cylinder after it cooled down at night. Next morning,,,,go to start it, and big white clouds out of the tail pipe. After it warmed up, it went on a 3000mile trip with no problems and no coolant usage, untill you shut it down and let it sit.[/U] This is the only real way it can get into the cylinders.» (post #28)
2) «Check your crankcase breather hose. I have an 01 duramax that blew the coolant out the breather as fast as it leaked into the oil and was nearly impossible to tell where the coolant was going because it only dripped when the engine was at higher RPM's, and it didn't wet anything coming out the end of the hose.» (post #30)
«I still don't know for sure what's wrong or where it is leaking. I pulled the injector sleeves and found a bad Oring on #6 injector but can't for the life of me figure out how it could be leaking that much. Right now it has sealer in the coolant and it seems to be working. I was thinking it might be the oil cooler but was told it would put oil in the coolant and that has never happened. A leaking head gasket will put extra pressure in the radiator and that is not happening either. I'm looking for ideas....what is it» (post #33)
«Did you check the end of the breather hose for droplets of coolant? On mine it would never drip on the concrete where I park. I had to get a drop on my finger and taste it. It may be black and not look like coolant but in my case it was. My oil level never seemed to rise.» (post #37)
What can i do to be sure that none of them are affecting my car? It's my final question.
Let me just say this, with my car's symptoms in the event of an internal coolant leak (into the engine) the smoke upon start-up can ONLY be due to the two causes illustrated on these two examples:
1)«It is very very unlikely you will loos it throught the exhaust because it is always under pressure. (...) then loosing it into the cylinder is almost a unlikely because the cylinder is always under pressure. Most likely it is pressurizing the cooling system and blowing the coolant out the tube. Water pump then oil cooler, Good luck.» (post #26)
[U]«I had one that would fill the cylinder after it cooled down at night. Next morning,,,,go to start it, and big white clouds out of the tail pipe. After it warmed up, it went on a 3000mile trip with no problems and no coolant usage, untill you shut it down and let it sit.[/U] This is the only real way it can get into the cylinders.» (post #28)
2) «Check your crankcase breather hose. I have an 01 duramax that blew the coolant out the breather as fast as it leaked into the oil and was nearly impossible to tell where the coolant was going because it only dripped when the engine was at higher RPM's, and it didn't wet anything coming out the end of the hose.» (post #30)
«I still don't know for sure what's wrong or where it is leaking. I pulled the injector sleeves and found a bad Oring on #6 injector but can't for the life of me figure out how it could be leaking that much. Right now it has sealer in the coolant and it seems to be working. I was thinking it might be the oil cooler but was told it would put oil in the coolant and that has never happened. A leaking head gasket will put extra pressure in the radiator and that is not happening either. I'm looking for ideas....what is it» (post #33)
«Did you check the end of the breather hose for droplets of coolant? On mine it would never drip on the concrete where I park. I had to get a drop on my finger and taste it. It may be black and not look like coolant but in my case it was. My oil level never seemed to rise.» (post #37)
What can i do to be sure that none of them are affecting my car? It's my final question.
Last edited by CaymanPower; 05-14-2010 at 01:57 PM.
05-14-2010, 04:59 PM
#21
Race Director
Macster,
At this point, I just want to eliminate the possibility of a coolant leak into the engine which could cause AOS overwhelming and hence somoke upon cold start-up. The following is what I know so far:
1) There's no visual evidence of coolant in the oil;
2) There's no visual evidence of oil in the coolant;
3) There's no evidence of combustion gases going into the coolant.
How do I know:
1) The oil was changed and no milkshake;
2)The coolant wasn't changed but its colour on a sample that came off when the filler cap was opened with a warm engine is a 'clean' pink;
3) I opened up the filler cap and started-up the engine, no bubbling or rised coolant level was observed .
Now, my doubts:
1) Is it sufficient to do a visual inspection, or I may need an oil analysis(as you state)?
2) Is the coolant sample from the filler neck good enough?
3) Should I have opened the filler cap only after the engine was started-up to first rise the pressure and then look for bubbles or 'spitted' coolant from the filler neck ?
4) How is the pressure test done in a engine/cooling system hot?
5) What else do I need to ask, besides an oil analysis, to make sure that my engine has no internal coolant leak?
At this point, I just want to eliminate the possibility of a coolant leak into the engine which could cause AOS overwhelming and hence somoke upon cold start-up. The following is what I know so far:
1) There's no visual evidence of coolant in the oil;
2) There's no visual evidence of oil in the coolant;
3) There's no evidence of combustion gases going into the coolant.
How do I know:
1) The oil was changed and no milkshake;
2)The coolant wasn't changed but its colour on a sample that came off when the filler cap was opened with a warm engine is a 'clean' pink;
3) I opened up the filler cap and started-up the engine, no bubbling or rised coolant level was observed .
Now, my doubts:
1) Is it sufficient to do a visual inspection, or I may need an oil analysis(as you state)?
2) Is the coolant sample from the filler neck good enough?
3) Should I have opened the filler cap only after the engine was started-up to first rise the pressure and then look for bubbles or 'spitted' coolant from the filler neck ?
4) How is the pressure test done in a engine/cooling system hot?
5) What else do I need to ask, besides an oil analysis, to make sure that my engine has no internal coolant leak?
If you suspect a coolant leak into the engine's oil system an oil analysis the only way to eliminate this possibility. Absence of signs of coolant in the oil is not 100% confirmation there is no leak into the oil. It may just be the leak has not developed fully yet. The analysis must be done by a facility that specifically tests for the chemicals used in anti-freeze.
Now, if the loss of coolant is large and the oil comes out of the engine sans any signs of coolant/water then the odds are the coolant is not making it into the oil and the analysis could be skipped.
I do not know what you refer to by asking of a coolant sample from the filler neck is good enough. If you are seeking to test the coolant for something ideally you want coolant that is circulating in the engine. Coolant in the tank is generally stagnet and its chemical composition may not reflect that of the majority of the coolant in the cooling system.
The cooling system can only develop pressure if the cap is on and the cooling system relatively pressure tight to begin with. Then engine must be run long enough and under sufficent load to fully heat the engine, coolant and oil. IOWs, the engine wants to be brought up to operating temperature.
If there is a pressure leak above the level of fluid in the cooling system pressure will of course escape. The engine can develop localized hot spots cause the lack of pressure allows hot coolant to flash to steam upon contact with the hotter portions of the engine (heads). This steam then acts to block coolant flow and the area becomes quite overheated. Head (or block) damage can result.
Even if the system does not get hot enough to result in localized overheating water can be lost through the hole as the hot vapor in the cooling system vents to atmosphere. In the case of a leaking coolant cap there might be condensation around the cap or on surfaces nearby. For a while.
If the leak is below the fluid level it may not allow any fluid to leak out until the pressure rises high enough to force some out. This happens when the engine is up to operating temperature and a bit hotter. These engines vary in how hot they run. Operating temperature is a general term. I've seen my Boxster's coolant run around 190F at highway speeds in cold weather to 226F at highway speeds in extremely hot weather.
Cold weather, even cool weather is very good at masking cooling system problems. The cooling system develops a leak that only very rarely becomes active. Most of the time the engine never gets hot enough to leak enough fluid the driver notices. If the light doesn't come on everything's assumed to be ok. No one checks the coolant level until the light comes on.
I'm not aware the pressure test can done with the coolant hot. Generally I guess the assumption is if there is a leak hot there'll be a leak cold.
If the system is losing coolant and yet the leak test failed to turn up a leak and there is no coolant in the oil then this would be pretty conclusive a leak exists that does not show itself when the system tested cold.
The only way I know of to be sure there is no internal coolant leak, a leak that is having coolant get into the oil, is to run an analysis on the engine oil looking for any trace of any anti-freeze chemicals in the oil. These remain even if the oil gets hot enough to boil away all traces of water.
Sincerely,
Macster.
05-14-2010, 05:14 PM
#22
Race Director
Macster,
Let me just say this, with my car's symptoms in the event of an internal coolant leak (into the engine) the smoke upon start-up can ONLY be due to the two causes illustrated on these two examples:
1)«It is very very unlikely you will loos it throught the exhaust because it is always under pressure. (...) then loosing it into the cylinder is almost a unlikely because the cylinder is always under pressure. Most likely it is pressurizing the cooling system and blowing the coolant out the tube. Water pump then oil cooler, Good luck.» (post #26)
[U]«I had one that would fill the cylinder after it cooled down at night. Next morning,,,,go to start it, and big white clouds out of the tail pipe. After it warmed up, it went on a 3000mile trip with no problems and no coolant usage, untill you shut it down and let it sit.[/U] This is the only real way it can get into the cylinders.» (post #28)
2) «Check your crankcase breather hose. I have an 01 duramax that blew the coolant out the breather as fast as it leaked into the oil and was nearly impossible to tell where the coolant was going because it only dripped when the engine was at higher RPM's, and it didn't wet anything coming out the end of the hose.» (post #30)
«I still don't know for sure what's wrong or where it is leaking. I pulled the injector sleeves and found a bad Oring on #6 injector but can't for the life of me figure out how it could be leaking that much. Right now it has sealer in the coolant and it seems to be working. I was thinking it might be the oil cooler but was told it would put oil in the coolant and that has never happened. A leaking head gasket will put extra pressure in the radiator and that is not happening either. I'm looking for ideas....what is it» (post #33)
«Did you check the end of the breather hose for droplets of coolant? On mine it would never drip on the concrete where I park. I had to get a drop on my finger and taste it. It may be black and not look like coolant but in my case it was. My oil level never seemed to rise.» (post #37)
What can i do to be sure that none of them are affecting my car? It's my final question.
Let me just say this, with my car's symptoms in the event of an internal coolant leak (into the engine) the smoke upon start-up can ONLY be due to the two causes illustrated on these two examples:
1)«It is very very unlikely you will loos it throught the exhaust because it is always under pressure. (...) then loosing it into the cylinder is almost a unlikely because the cylinder is always under pressure. Most likely it is pressurizing the cooling system and blowing the coolant out the tube. Water pump then oil cooler, Good luck.» (post #26)
[U]«I had one that would fill the cylinder after it cooled down at night. Next morning,,,,go to start it, and big white clouds out of the tail pipe. After it warmed up, it went on a 3000mile trip with no problems and no coolant usage, untill you shut it down and let it sit.[/U] This is the only real way it can get into the cylinders.» (post #28)
2) «Check your crankcase breather hose. I have an 01 duramax that blew the coolant out the breather as fast as it leaked into the oil and was nearly impossible to tell where the coolant was going because it only dripped when the engine was at higher RPM's, and it didn't wet anything coming out the end of the hose.» (post #30)
«I still don't know for sure what's wrong or where it is leaking. I pulled the injector sleeves and found a bad Oring on #6 injector but can't for the life of me figure out how it could be leaking that much. Right now it has sealer in the coolant and it seems to be working. I was thinking it might be the oil cooler but was told it would put oil in the coolant and that has never happened. A leaking head gasket will put extra pressure in the radiator and that is not happening either. I'm looking for ideas....what is it» (post #33)
«Did you check the end of the breather hose for droplets of coolant? On mine it would never drip on the concrete where I park. I had to get a drop on my finger and taste it. It may be black and not look like coolant but in my case it was. My oil level never seemed to rise.» (post #37)
What can i do to be sure that none of them are affecting my car? It's my final question.
I will say generally speaking it is possible for an engine to have an intermix problem and to lose coolant through the exhaust. The heads have coolant passages that run right close the exhaust valve. A crack in the head can have coolant leak into the exhaust sytem and this coolant liquid will be ejected when the engine is started. The coolant will almost certainly exit the exhaust as fluid, liquid, and not as water vapor unless the engine started hot. Regardless, the exhaust should have a strong smell of anti-freeze. Any fluid that comes out of the exhaust will almost be black -- from soot it has washed from the exhaust system walls -- but it will not be oil but water with of course anti-freeze in it.
Some M96 engines could develop a crack in a cylinder wall which could also have some coolant seep into the cylinder and be shoved out the exhaust port upon engine start. The cylinder can't hold much water or the engine will lock up so there's a limit to how much fluid can exit the exhaust.
A cooling system pressure test should uncover any cracks in the heads or a crack in a cylinder wall. I mean I find it hard to believe a head crack (or a head gasket leak) or a cylinder wall crack could be bad enough to allow enough coolant to leak out to contribute to smoking upon startup -- assuming the smoking is water vapor and not oil smoke or smoke of another nature/source -- and yet not show up with a cooling system pressure test.
If you suspect there is a coolant leak into the engine -- I repeat what I posted earlier -- an oil analysis looking for the presence of anti-freeze chemicals in the oil is called for.
If the analysis turns up no signs of anti-freeze chemicals in the oil then one can remove coolant leaking into the engine oil from the list of possible paths the coolant is taking out of the cooling system.
If the coolant level is not remaining stable there is almost certainly a coolant leak, but the engine oil sump is not the recipient of the leaking coolant.
Sincerely,
Macster.
05-15-2010, 12:25 AM
#23
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Macster,
Thank you for taking the time to share. Very educational!
I think this pretty much sums it up. Unless, the coolant would seep into the cylinder just after the engine is shutted off, when the cylinder is no longer under gas pressure, and remains hot enough for the leak to develop, provided the leak is temperature related. Then, next morning, big cloud of smoke out of the tail pipe. In that case, i think it would likely happen quite the contrary of what you'd normally expect, the smoke upon start-up would be increasingly severe as harder you had run the engine before (the higher the temperature after engine shut off the longer the leak is sustained, which means more coolant seeping into the cylinder). You may argue that in such event we likely would see some sort of bublling or fluid coming out of the filler neck if the cap was to be removed with the engine warming up. Well, as i already said before i did opened the coolant cap and couldn't see any bubbles nor did the coolant came out after I've started the engine with the coolant cap off (maybe i didn't wait long enough for the temperature to rise to the point that the leak would appear). I suppose if there was a crack allowing coolant to enter the cylinder when the engine is shutted off and left to cool (but still hot enough) then, while the engine was running, some combustion gases would likely to escape through that same crack showing up as bubbles or causing the coolant to be spilled out the filler neck with the cap off. But, i'm not sure it will be always the case.
Some confirmation from you would be appreciated.
Thank you for taking the time to share. Very educational!
A cooling system pressure test should uncover any cracks in the heads or a crack in a cylinder wall. I mean I find it hard to believe a head crack (or a head gasket leak) or a cylinder wall crack could be bad enough to allow enough coolant to leak out to contribute to smoking upon startup -- assuming the smoking is water vapor and not oil smoke or smoke of another nature/source -- and yet not show up with a cooling system pressure test.
Some confirmation from you would be appreciated.
Last edited by CaymanPower; 05-15-2010 at 09:31 AM.
05-17-2010, 11:27 AM
#24
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If any antifreeze chemicals are found in the oil you know engine has a coolant leak, intermix problem. AOS is as good as anything to suspect cause these have a habit of going bad though causing an intermix problem is not a problem I've come across.
However, if the AOS has a coolant passage in it, this is certainly a place for a leak to develop.
If AOS is the source of the intermix problem then after you replace the AOS and the oil contaminated with the coolant the smoking upon startup should probably diminish. First no more intermix problem and second the new AOS is probably more efficient at removing oil vapor from crankcase fumes *befure* these fumes make it to the instake manifold.
(...)
Note if you find the leak is not from the AOS and after the leak fixed and the smoking continues and there are any other untoward engine behavior the AOS could very well be bad -- just not leaking coolant -- and needs to be replaced.
Sincerely,
Macster.
However, if the AOS has a coolant passage in it, this is certainly a place for a leak to develop.
If AOS is the source of the intermix problem then after you replace the AOS and the oil contaminated with the coolant the smoking upon startup should probably diminish. First no more intermix problem and second the new AOS is probably more efficient at removing oil vapor from crankcase fumes *befure* these fumes make it to the instake manifold.
(...)
Note if you find the leak is not from the AOS and after the leak fixed and the smoking continues and there are any other untoward engine behavior the AOS could very well be bad -- just not leaking coolant -- and needs to be replaced.
Sincerely,
Macster.
Good news!
Finally, dealer saw the "heavy" smoke and agreed that it wasn't normal, so he ordered a new AOS to replace the existing one and see if the problem comes from there. As a side note, I can tell you that when i took off the oil filler cap with the engine running i felt a strong vacuum and the engine was in the verge of stalling.
