Air/Oil Separator
12-05-2008, 12:03 PM
#1
Rennlist Member
Thread Starter
Air/Oil Separator
This may be one of those "don't trouble troubles unles trouble troubles you" topics BUT:
I was driving my car a few months ago and it was idleing poorly. I had added some oil and left the oil cap loose. Once I put it on properly, no problem. While searching a thread here, I saw a check for a/o separator that said "take the oil cap off, if the cars stalls the a/o separator is bad". So I took my cap off and again the car ran rough but didn't stall. I put my hand over the oil fill and felt a slight negative pressure.
Mind you, I have no other symptoms that I know of (ie no smoke, no check engine light...nothing).
Should I be concerned? Any other checks?
I was driving my car a few months ago and it was idleing poorly. I had added some oil and left the oil cap loose. Once I put it on properly, no problem. While searching a thread here, I saw a check for a/o separator that said "take the oil cap off, if the cars stalls the a/o separator is bad". So I took my cap off and again the car ran rough but didn't stall. I put my hand over the oil fill and felt a slight negative pressure.
Mind you, I have no other symptoms that I know of (ie no smoke, no check engine light...nothing).
Should I be concerned? Any other checks?
12-05-2008, 12:10 PM
#2
Race Car
Pat, if it doesnt kill the motor, you are more than likely ok.
When mine went, it made a metal to metal screeching sound, similar to a bad idler pulley that squeeks every revolution of the motor.
Once the oil cap was removed, it instantly leaned out and died.
When I put the new one in, it barely affected idle and just had a minimal drop in RPM. The vacuum pull was very low but evident.
Hope this helps.
When mine went, it made a metal to metal screeching sound, similar to a bad idler pulley that squeeks every revolution of the motor.
Once the oil cap was removed, it instantly leaned out and died.
When I put the new one in, it barely affected idle and just had a minimal drop in RPM. The vacuum pull was very low but evident.
Hope this helps.
12-05-2008, 12:29 PM
#4
Race Car
12-05-2008, 10:13 PM
#5
Rennlist Member
Pat, if it doesnt kill the motor, you are more than likely ok.
When mine went, it made a metal to metal screeching sound, similar to a bad idler pulley that squeeks every revolution of the motor.
Once the oil cap was removed, it instantly leaned out and died.
When I put the new one in, it barely affected idle and just had a minimal drop in RPM. The vacuum pull was very low but evident.
Hope this helps.
When mine went, it made a metal to metal screeching sound, similar to a bad idler pulley that squeeks every revolution of the motor.
Once the oil cap was removed, it instantly leaned out and died.
When I put the new one in, it barely affected idle and just had a minimal drop in RPM. The vacuum pull was very low but evident.
Hope this helps.
When mine went, idle increased and cold starting was more problematic. There is a test for the AOS. Callas Rennsport had some sort of tube thingy gauge. It took a few seconds and they could see the AOS was bad.
12-05-2008, 10:51 PM
#6
Race Car
If the intake system and AOS is functioning properly, Porsche specs call for the idle to slightly increase (+40 rpm) and timing to be pulled a little (1.5 degrees) when the oil cap is removed.
12-06-2008, 12:46 AM
#7
Race Car
40-50 RPM gain is about my estimate too with the new AOS installed.
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12-06-2008, 12:50 AM
#8
Race Car
Although, not sure if it is a result of AOS failure, a Service Manager said that when the AOS fails, it takes out the MAF with it. I thought BS when I was leaving with the new one.
But, when I was trying to rid my car of the CEL (new AOS installed), we searched an o2 problem (what we thought from the print-out) for a few days on mine and sure enough, the MAF was dead as he said.
I still can't figure this one out and still feel it is coincidental.
But, when I was trying to rid my car of the CEL (new AOS installed), we searched an o2 problem (what we thought from the print-out) for a few days on mine and sure enough, the MAF was dead as he said.
I still can't figure this one out and still feel it is coincidental.
12-06-2008, 02:29 AM
#10
Rennlist Member
12-06-2008, 02:35 PM
#11
Race Director
My '02 Boxster's first AOS failure removing the oil tube filler...
This may be one of those "don't trouble troubles unles trouble troubles you" topics BUT:
I was driving my car a few months ago and it was idleing poorly. I had added some oil and left the oil cap loose. Once I put it on properly, no problem. While searching a thread here, I saw a check for a/o separator that said "take the oil cap off, if the cars stalls the a/o separator is bad". So I took my cap off and again the car ran rough but didn't stall. I put my hand over the oil fill and felt a slight negative pressure.
Mind you, I have no other symptoms that I know of (ie no smoke, no check engine light...nothing).
Should I be concerned? Any other checks?
I was driving my car a few months ago and it was idleing poorly. I had added some oil and left the oil cap loose. Once I put it on properly, no problem. While searching a thread here, I saw a check for a/o separator that said "take the oil cap off, if the cars stalls the a/o separator is bad". So I took my cap off and again the car ran rough but didn't stall. I put my hand over the oil fill and felt a slight negative pressure.
Mind you, I have no other symptoms that I know of (ie no smoke, no check engine light...nothing).
Should I be concerned? Any other checks?
I could see if AOS pulling that much vacuum that if one could get the cap off it could overwhelm the engine controller's controller's ability to adapt and the engine could die.
A normal/healthy engine and engine controller can very easily adapt to the removal of the oil tube filler cap and of course its being installed afterwards.
Second time AOS failed there was alot of oil smoke upon startup that continued. Always before when there was oil smoke upon startup and this rare it was just a brief event. But in this case the engine just kept emitting a steady cloud of oil smoke.
In both cases MAF was unaffected. I even cleaned the MAF the first time -- after 80,000 miles from new -- and found no dirt on the MAF. Used cleaner and let cleaner fluid drip on clean white paper towels and no dirt. The throttle body now was dirty, a bit oily.
Second time I never even bothered to clean the MAF or have plugs replaced. Just had car flatbedded to dealer and had the AOS changed.
In both cases afterwards, I ran a bottle or two of Techron through engine -- following directions -- to help remove any engine deposits the oil burning might have caused. I changed the oil afterwards, too, which is my standard operating procedure after using Techron.
Sincerely,
Macster.
12-06-2008, 02:44 PM
#12
Race Director
The MAF being bas was coincidental, or it may not have even been...
Although, not sure if it is a result of AOS failure, a Service Manager said that when the AOS fails, it takes out the MAF with it. I thought BS when I was leaving with the new one.
But, when I was trying to rid my car of the CEL (new AOS installed), we searched an o2 problem (what we thought from the print-out) for a few days on mine and sure enough, the MAF was dead as he said.
I still can't figure this one out and still feel it is coincidental.
But, when I was trying to rid my car of the CEL (new AOS installed), we searched an o2 problem (what we thought from the print-out) for a few days on mine and sure enough, the MAF was dead as he said.
I still can't figure this one out and still feel it is coincidental.
Several years ago car emitted error codes that hinted at a MAF problem. Even got a sort of diagnosis from dealer tech who when I had car in for something else hooked up computer and told me the MAF adaptation was wrong.
Finally broke down and bought a new MAF to replace the original MAF that had been in the car since new (since '02 and had racked up oh roughly 120,000 miles at that time).
New MAF appeared to solve problem for a day or so. Then the error codes came back. Looking over car some more with co-worker and he heard (my hearing's not good) a vacuum leak around oil tube filler cap. Replaced this for less than $20 with new one. Problem solved.
This new MAF recently became suspect and after ensuring the oil tube filler cap not leaking I replaced this second MAF with the original one I had saved.
The original one worked just fine and it was the 2nd MAF, that had racked up close to 80,000 miles. (Car now has over 207,000 miles on it.)
The only way a failing AOS could take out a MAF is if tech drops wrench on MAF while removing AOS. Now it could be that MAF was just ready to go bad and it going bad was just a coincidence. These do happen.
Oh, after 1st AOS, car still emitting error codes. I forget now what they were. I finally diagnosed the problem to a bad O2 sensor and replaced it, had dealer replace just the one I diagnosed. Problem solved. In this case the failing AOS and the dose of oil it fed the engine may *may* have accelerated the demise of the O2 sensor, though I note that at 80,000 miles the O2 sensor could have been probably was near the end of its life anyway.
Sincerely,
Macster.
12-06-2008, 03:00 PM
#13
Race Car
Although, not sure if it is a result of AOS failure, a Service Manager said that when the AOS fails, it takes out the MAF with it. I thought BS when I was leaving with the new one.
But, when I was trying to rid my car of the CEL (new AOS installed), we searched an o2 problem (what we thought from the print-out) for a few days on mine and sure enough, the MAF was dead as he said.
I still can't figure this one out and still feel it is coincidental.
But, when I was trying to rid my car of the CEL (new AOS installed), we searched an o2 problem (what we thought from the print-out) for a few days on mine and sure enough, the MAF was dead as he said.
I still can't figure this one out and still feel it is coincidental.
Just another example illustrating the lack of technical knowledge the Porsche Service Managers have.
12-06-2008, 09:14 PM
#15
Race Car
The sound I believe is just the rush of air either past the ruptured diaphram or simply through the housing itself.
No, I meant when I would remove the oil cap after I put in the new AOS, it only raised the RPM by about 50 as '99 said.
cap did not kill engine, cause I couldn't remove it against the pressure difference! Unscrew it, yes. But could not lift cap off.
I could see if AOS pulling that much vacuum that if one could get the cap off it could overwhelm the engine controller's controller's ability to adapt and the engine could die.
Sincerely,
Macster.
I could see if AOS pulling that much vacuum that if one could get the cap off it could overwhelm the engine controller's controller's ability to adapt and the engine could die.
Sincerely,
Macster.
bad.
Several years ago car emitted error codes that hinted at a MAF problem. Even got a sort of diagnosis from dealer tech who when I had car in for something else hooked up computer and told me the MAF adaptation was wrong.
Finally broke down and bought a new MAF to replace the original MAF that had been in the car since new (since '02 and had racked up oh roughly 120,000 miles at that time).
New MAF appeared to solve problem for a day or so. Then the error codes came back. Looking over car some more with co-worker and he heard (my hearing's not good) a vacuum leak around oil tube filler cap. Replaced this for less than $20 with new one. Problem solved.
This new MAF recently became suspect and after ensuring the oil tube filler cap not leaking I replaced this second MAF with the original one I had saved.
The original one worked just fine and it was the 2nd MAF, that had racked up close to 80,000 miles. (Car now has over 207,000 miles on it.)
The only way a failing AOS could take out a MAF is if tech drops wrench on MAF while removing AOS. Now it could be that MAF was just ready to go bad and it going bad was just a coincidence. These do happen.
Oh, after 1st AOS, car still emitting error codes. I forget now what they were. I finally diagnosed the problem to a bad O2 sensor and replaced it, had dealer replace just the one I diagnosed. Problem solved. In this case the failing AOS and the dose of oil it fed the engine may *may* have accelerated the demise of the O2 sensor, though I note that at 80,000 miles the O2 sensor could have been probably was near the end of its life anyway.
Sincerely,
Macster.
Several years ago car emitted error codes that hinted at a MAF problem. Even got a sort of diagnosis from dealer tech who when I had car in for something else hooked up computer and told me the MAF adaptation was wrong.
Finally broke down and bought a new MAF to replace the original MAF that had been in the car since new (since '02 and had racked up oh roughly 120,000 miles at that time).
New MAF appeared to solve problem for a day or so. Then the error codes came back. Looking over car some more with co-worker and he heard (my hearing's not good) a vacuum leak around oil tube filler cap. Replaced this for less than $20 with new one. Problem solved.
This new MAF recently became suspect and after ensuring the oil tube filler cap not leaking I replaced this second MAF with the original one I had saved.
The original one worked just fine and it was the 2nd MAF, that had racked up close to 80,000 miles. (Car now has over 207,000 miles on it.)
The only way a failing AOS could take out a MAF is if tech drops wrench on MAF while removing AOS. Now it could be that MAF was just ready to go bad and it going bad was just a coincidence. These do happen.
Oh, after 1st AOS, car still emitting error codes. I forget now what they were. I finally diagnosed the problem to a bad O2 sensor and replaced it, had dealer replace just the one I diagnosed. Problem solved. In this case the failing AOS and the dose of oil it fed the engine may *may* have accelerated the demise of the O2 sensor, though I note that at 80,000 miles the O2 sensor could have been probably was near the end of its life anyway.
Sincerely,
Macster.