Smoking at high revs

[Gramuno]

Hi all,

Great site, full of usefull info.

I've been having problems with my 2000 S which i'm hoping someone may be able to help before i loose all confidence in the Porsche brand.

It has started to smoke lots when i accellerate hard over 5000rpm. It would be as though the oil breather system is getting pressurised and dumping all the excess oil into the intake manifold.

I took it to a local Porsche specialist where i have had work/servicing done previously who replaced the AOS and gave it back to me saying it was fixed.....which i found not to be the case after 1 journey!

They had it back and looked harder a the breather system which led them cleaning a small pressure relief valve (on a pipe from the AOS to the front lhs of the engine) but also i asked them to do compression and cylinder leakage tests which came up ok and then gave me it back saying it was fixed....it wasn't.

The most recent time they have had it, they have taken both oil scavenge pumps out to check to make sure they are working correctly...they say they are and so the next course of action was to take the engine out and dismantly it!!!! Due to this i asked them to recheck the oil breather system to which they did....apparently and then said it doesn't appear to be letting oil inthrough that route.

I collected the car from them totally dissatisfied only to start the car at the garage where the CEL came on. They plugged their PST2 into it and said it was one of the pre cat o2 sensors reset it then i went on my way.

The light has come back on now and i am assuming all the oil going through the exhuast will have broke the sensors. I'm getting a OBD2 reader to make sure, and not taking it back to the garage!

I have just had the throttle body and pipework off to find a fair bit of oil in the pipes. To me this would still indicate the oil breather system and not internal engine problems.

Does anyone have experience with fitting an AOS that was defective? can i take the pipe from the AOS to the intake out plugging the hole in the intake and watching the aos pipe whilst driving?

Any comments would be much appreciated

Thanks

Graeme

[catmanluge]

Hi all,

Great site, full of usefull info.

I've been having problems with my 2000 S which i'm hoping someone may be able to help before i loose all confidence in the Porsche brand.

It has started to smoke lots when i accellerate hard over 5000rpm. It would be as though the oil breather system is getting pressurised and dumping all the excess oil into the intake manifold.

I took it to a local Porsche specialist where i have had work/servicing done previously who replaced the AOS and gave it back to me saying it was fixed.....which i found not to be the case after 1 journey!

They had it back and looked harder a the breather system which led them cleaning a small pressure relief valve (on a pipe from the AOS to the front lhs of the engine) but also i asked them to do compression and cylinder leakage tests which came up ok and then gave me it back saying it was fixed....it wasn't.

The most recent time they have had it, they have taken both oil scavenge pumps out to check to make sure they are working correctly...they say they are and so the next course of action was to take the engine out and dismantly it!!!! Due to this i asked them to recheck the oil breather system to which they did....apparently and then said it doesn't appear to be letting oil inthrough that route.

I collected the car from them totally dissatisfied only to start the car at the garage where the CEL came on. They plugged their PST2 into it and said it was one of the pre cat o2 sensors reset it then i went on my way.

The light has come back on now and i am assuming all the oil going through the exhuast will have broke the sensors. I'm getting a OBD2 reader to make sure, and not taking it back to the garage!

I have just had the throttle body and pipework off to find a fair bit of oil in the pipes. To me this would still indicate the oil breather system and not internal engine problems.

Does anyone have experience with fitting an AOS that was defective? can i take the pipe from the AOS to the intake out plugging the hole in the intake and watching the aos pipe whilst driving?

Any comments would be much appreciated

Thanks

Graeme

[catmanluge]

Hi all,

Great site, full of usefull info.

I've been having problems with my 2000 S which i'm hoping someone may be able to help before i loose all confidence in the Porsche brand.

It has started to smoke lots when i accellerate hard over 5000rpm. It would be as though the oil breather system is getting pressurised and dumping all the excess oil into the intake manifold.

I took it to a local Porsche specialist where i have had work/servicing done previously who replaced the AOS and gave it back to me saying it was fixed.....which i found not to be the case after 1 journey!

They had it back and looked harder a the breather system which led them cleaning a small pressure relief valve (on a pipe from the AOS to the front lhs of the engine) but also i asked them to do compression and cylinder leakage tests which came up ok and then gave me it back saying it was fixed....it wasn't.

The most recent time they have had it, they have taken both oil scavenge pumps out to check to make sure they are working correctly...they say they are and so the next course of action was to take the engine out and dismantly it!!!! Due to this i asked them to recheck the oil breather system to which they did....apparently and then said it doesn't appear to be letting oil inthrough that route.

I collected the car from them totally dissatisfied only to start the car at the garage where the CEL came on. They plugged their PST2 into it and said it was one of the pre cat o2 sensors reset it then i went on my way.

The light has come back on now and i am assuming all the oil going through the exhuast will have broke the sensors. I'm getting a OBD2 reader to make sure, and not taking it back to the garage!

I have just had the throttle body and pipework off to find a fair bit of oil in the pipes. To me this would still indicate the oil breather system and not internal engine problems.

Does anyone have experience with fitting an AOS that was defective? can i take the pipe from the AOS to the intake out plugging the hole in the intake and watching the aos pipe whilst driving?

Any comments would be much appreciated

Thanks

Graeme

It still sounds like the AOS I would try changing the AOS as my best guess. Clean the intake really good before starting plus the exhaust system could still have a lot of excess oil.

Catman

[wvicary]

I once had a 2.7l Boxster that took 30 km of driving to burn the excess oil out of the exhaust system after the separator was changed. I wouldn't operate the engine with the AOS disconnected or plugged off as you risk creating too much internal engine pressure which could cause a seal to fail or at least make one hell of a mess.

Check the oil level and take her out for a good, long drive.

[Gramuno]

Thanks guys,

I have driven about 300 miles since it was replaced the first time. The intake has been cleaned, it just gets more thrown in from the AOS.

Is there anything that could be forcing too much oil into the AOS that it can't cope?

[pomocanthus]

How much oil do you have in the car? About six months ago I was in a hurry and had a chain store change my oil. After bringing my '99 Tip home, the dash indicator showed low oil. I checked for leaks and didn't find any so I added more oil (about a quart). The dash indicator showed oil is full. Since then the car has been sluggish and smokes intermittently (sometimes at startup, sometimes during normal cruising, sometimes at high revs). I cleaned out the throttle body and idle control valve. There was a lot of oil in the J-tube from the AOS to the TB. There was also a lot of oil in the intake manifolds. I thought it was a failed AOS so proceeded to replace. After pulling the AOS, there was no evidence of AOS failure. Bellows was intact and no sign of wear but since I already bought a new one, I installed the new one. I clean off all oil and put everything back together. To my dismay she still smoked after over 100 miles of driving and still sluggish and there was oil once again in the newly cleaned intake and TB. I then changed my oil and drained more than 10 quarts; apparently TOO much oil. I also changed the plugs and there was evidence of oil in 2 of the 6 spark plug chambers (there was oil on the coil packs). Somehow the excess oil worked its way past the plugs. After more cleaning and new plugs torqued correctly, she is running like a champ. No more smoke. Although 82K, she is running like she is 32. Moral of the story is to NOT overfill your oil and use the dip stick as a gage and not the dash indicator.

Don't give up! I was ready to throw in the towel when I started reading all the threads here. With the help from Stefan, Bruce, Insite, Tool Pants, and others, I managed to save myself a lot of money and more importantly my faith in the Porsche marque. When hauling butt around a curve, with the engine begging for more throttle, wind in your hair, you realize why you put up with the agony. I can now proudly say I can do most of the servicing myself and no longer fear for my savings when something seem to go wrong. It is another opportunity to learn how my car works. Besides what are you going to do, go back to driving a Camry?

Good luck and have faith,

Hung

Edited January 10, 2008 by pomocanthus