Disappearing oil in 02 C4S
06-19-2017, 10:47 AM
#31
if you mean idle change when you remove the oil fill cap...I believe that to be normal. I bought an @ $35 digital manometer on Flea-bay which worked fine. Just make sure it is set to the right scale!
06-19-2017, 12:15 PM
#32
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UPDATE 6-18-2017
1) I added 1.5 quarts of Mobil 1 0W-40. This morning at a cold start, later fully warmed up after filling up with gas, and 6 hours after last driving it the dipstick and electronic meter both read full. Car continues to drive well and sounds good as far as I can tell.
2) I did a cursory check on the AOS by removing the oil fill cap. I don't yet have any type of manometer. With the engine fully warmed up and at idle, the cap came off without much effort. There was definitely a vacuum. Covering it with my hand it not did not alter the idle at all. With the engine sitting for 6 hours and then starting it and repeating this test there was about the same vacuum (simply qualitatively determined by how much I felt pulling on my hand, so not quantitatively) but with my hand off the filler tube so it was open the idle got rough. Not to the point it stalled but definitely changed. The coolant tank is roughly just under full, as it has been since the indy shop topped it off 3 weeks ago during an inspection. Still the only smoke I see is when starting a cold engine after it was last run and shut down cold (as in I ran it to move it around the driveway). There is no noticeable smoke during driving or starting the engine while warm or if it was last shut down warm after a drive. In parallel to tracking my oil consumption I'm going to build/buy a manometer to quantify the vacuum. Since the AOS seems to fail at a high rate and is somewhat time consuming to replace it seems helpful to measure this.
Is any change in idle indicative of an AOS failure?
Next steps this week:
a) Will continue to monitor gas mileage, oil consumption vs mileage, coolant level, and amount of soot on tailpipes (I wiped these clean to provide a baseline) over the next 2-3 weeks.
b) I expect to be able to change both the oil and filter later this week. At this point I'll also install the the magnetic oil plug I ordered.
c) Build/buy a manometer and quantify the vacuum pressure.
1) I added 1.5 quarts of Mobil 1 0W-40. This morning at a cold start, later fully warmed up after filling up with gas, and 6 hours after last driving it the dipstick and electronic meter both read full. Car continues to drive well and sounds good as far as I can tell.
2) I did a cursory check on the AOS by removing the oil fill cap. I don't yet have any type of manometer. With the engine fully warmed up and at idle, the cap came off without much effort. There was definitely a vacuum. Covering it with my hand it not did not alter the idle at all. With the engine sitting for 6 hours and then starting it and repeating this test there was about the same vacuum (simply qualitatively determined by how much I felt pulling on my hand, so not quantitatively) but with my hand off the filler tube so it was open the idle got rough. Not to the point it stalled but definitely changed. The coolant tank is roughly just under full, as it has been since the indy shop topped it off 3 weeks ago during an inspection. Still the only smoke I see is when starting a cold engine after it was last run and shut down cold (as in I ran it to move it around the driveway). There is no noticeable smoke during driving or starting the engine while warm or if it was last shut down warm after a drive. In parallel to tracking my oil consumption I'm going to build/buy a manometer to quantify the vacuum. Since the AOS seems to fail at a high rate and is somewhat time consuming to replace it seems helpful to measure this.
Is any change in idle indicative of an AOS failure?
Next steps this week:
a) Will continue to monitor gas mileage, oil consumption vs mileage, coolant level, and amount of soot on tailpipes (I wiped these clean to provide a baseline) over the next 2-3 weeks.
b) I expect to be able to change both the oil and filter later this week. At this point I'll also install the the magnetic oil plug I ordered.
c) Build/buy a manometer and quantify the vacuum pressure.
The engine initially reacts with a drop in RPMs and some rough idling but very quickly the DME compensates. While the idle many not be as smooth as it was with the cap in place it will be better than it was right after the cap was removed.
When you replace the cap this of course removes the air intake leak and the engine is now running too rich. This is not that bad of a problem so the engine doesn't react quite vigorously to the overly rich condition but it does react. But again the DME adjusts the fueling and in nearly no time the engine should have its normally smooth idle back.
I can tell you after going through 3 AOS failures with my Boxster each failure was different. The first was accompanied by initial a bit of hesitation off icle and a varying idle speed. Nothing gruesome just the normal stable idle was instead "hunting". At some point -- towards the end of my attempt to diagonse the problem -- I found the oil filler tube cap impossible to remove while the engine was idling. The very last stage as I was positioning the car to get it on the flat bed tow truck was the exhaust started billowing oil smoke.
The 2nd failure started out during a long 2K mile road trip. At the end of a day's drive -- 12 hours or more -- while making my way on surface streets to my hotel or sitting at the freeway off ramp waiting for the light to change -- the CEL would come on concurrently with the engine manifesting just the slightest stumble. For hours prior to this the engine just purred. The error codes suggest a mixture problem and I suspected the MAF and decided I could press on.
After 2 days of driving I made it to my final destination and parked the car. The next AM upon cold start the oil smoke just billowed from the exhaust and I knew then what the CEL and error codes were trying to tell me.
The 3rd failure there were no symptoms. The car was running just fine. Took off from a stop light and by habit checked the rear view mirror and spottted a large cloud of something behind the car. Suspecting a failure in the cooling system I checked for any signs of trouble at the dash but all was ok. As I drove the smoking stopped but by this time I suspected it was an AOS. I made a u-turn with the idea of driving the 10 miles to the dealer but after just a mile or so the engine started smoking again and started running poorly so I parked the car and called AAA to tow the car.
Which AOS failure will you experience? Can't say. And there may be other variations too. After all my Boxster is only on its 3rd replacement AOS.
06-19-2017, 12:49 PM
#33
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The idle behavior you report is normal. Removing the cap with the engine idling introduces a big intake air leak and the engine goes lean.
The engine initially reacts with a drop in RPMs and some rough idling but very quickly the DME compensates. While the idle many not be as smooth as it was with the cap in place it will be better than it was right after the cap was removed.
When you replace the cap this of course removes the air intake leak and the engine is now running too rich. This is not that bad of a problem so the engine doesn't react quite vigorously to the overly rich condition but it does react. But again the DME adjusts the fueling and in nearly no time the engine should have its normally smooth idle back.
I can tell you after going through 3 AOS failures with my Boxster each failure was different. The first was accompanied by initial a bit of hesitation off icle and a varying idle speed. Nothing gruesome just the normal stable idle was instead "hunting". At some point -- towards the end of my attempt to diagonse the problem -- I found the oil filler tube cap impossible to remove while the engine was idling. The very last stage as I was positioning the car to get it on the flat bed tow truck was the exhaust started billowing oil smoke.
The 2nd failure started out during a long 2K mile road trip. At the end of a day's drive -- 12 hours or more -- while making my way on surface streets to my hotel or sitting at the freeway off ramp waiting for the light to change -- the CEL would come on concurrently with the engine manifesting just the slightest stumble. For hours prior to this the engine just purred. The error codes suggest a mixture problem and I suspected the MAF and decided I could press on.
After 2 days of driving I made it to my final destination and parked the car. The next AM upon cold start the oil smoke just billowed from the exhaust and I knew then what the CEL and error codes were trying to tell me.
The 3rd failure there were no symptoms. The car was running just fine. Took off from a stop light and by habit checked the rear view mirror and spotted a large cloud of something behind the car. Suspecting a failure in the cooling system I checked for any signs of trouble at the dash but all was ok. As I drove the smoking stopped but by this time I suspected it was an AOS. I made a u-turn with the idea of driving the 10 miles to the dealer but after just a mile or so the engine started smoking again and started running poorly so I parked the car and called AAA to tow the car.
Which AOS failure will you experience? Can't say. And there may be other variations too. After all my Boxster is only on its 3rd replacement AOS.
The engine initially reacts with a drop in RPMs and some rough idling but very quickly the DME compensates. While the idle many not be as smooth as it was with the cap in place it will be better than it was right after the cap was removed.
When you replace the cap this of course removes the air intake leak and the engine is now running too rich. This is not that bad of a problem so the engine doesn't react quite vigorously to the overly rich condition but it does react. But again the DME adjusts the fueling and in nearly no time the engine should have its normally smooth idle back.
I can tell you after going through 3 AOS failures with my Boxster each failure was different. The first was accompanied by initial a bit of hesitation off icle and a varying idle speed. Nothing gruesome just the normal stable idle was instead "hunting". At some point -- towards the end of my attempt to diagonse the problem -- I found the oil filler tube cap impossible to remove while the engine was idling. The very last stage as I was positioning the car to get it on the flat bed tow truck was the exhaust started billowing oil smoke.
The 2nd failure started out during a long 2K mile road trip. At the end of a day's drive -- 12 hours or more -- while making my way on surface streets to my hotel or sitting at the freeway off ramp waiting for the light to change -- the CEL would come on concurrently with the engine manifesting just the slightest stumble. For hours prior to this the engine just purred. The error codes suggest a mixture problem and I suspected the MAF and decided I could press on.
After 2 days of driving I made it to my final destination and parked the car. The next AM upon cold start the oil smoke just billowed from the exhaust and I knew then what the CEL and error codes were trying to tell me.
The 3rd failure there were no symptoms. The car was running just fine. Took off from a stop light and by habit checked the rear view mirror and spotted a large cloud of something behind the car. Suspecting a failure in the cooling system I checked for any signs of trouble at the dash but all was ok. As I drove the smoking stopped but by this time I suspected it was an AOS. I made a u-turn with the idea of driving the 10 miles to the dealer but after just a mile or so the engine started smoking again and started running poorly so I parked the car and called AAA to tow the car.
Which AOS failure will you experience? Can't say. And there may be other variations too. After all my Boxster is only on its 3rd replacement AOS.
Wow, exciting times with the AOS for you. So basically it can range from a slow incremental death of the AOS to an immediate sudden failure. They say variety is the spice of life though I'd prefer this to be vanilla. The replacement isn't too bad from what I've read here and on renntech, just a long tedious job especially if you don't drop the engine (which I will not be able to do at home). We'll see what the pressure reads once i get a manometer and keep an eye on it. If I have to replace it looks like i have some long nights after work ahead of me.
06-27-2017, 11:23 AM
#34
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Macster, so the idle will normally roughen up but it should come back to more or less smooth some time after I remove the oil fill cap. that is good to know.
Wow, exciting times with the AOS for you. So basically it can range from a slow incremental death of the AOS to an immediate sudden failure. They say variety is the spice of life though I'd prefer this to be vanilla. The replacement isn't too bad from what I've read here and on renntech, just a long tedious job especially if you don't drop the engine (which I will not be able to do at home). We'll see what the pressure reads once i get a manometer and keep an eye on it. If I have to replace it looks like i have some long nights after work ahead of me.
Wow, exciting times with the AOS for you. So basically it can range from a slow incremental death of the AOS to an immediate sudden failure. They say variety is the spice of life though I'd prefer this to be vanilla. The replacement isn't too bad from what I've read here and on renntech, just a long tedious job especially if you don't drop the engine (which I will not be able to do at home). We'll see what the pressure reads once i get a manometer and keep an eye on it. If I have to replace it looks like i have some long nights after work ahead of me.
I finally got my homemade manometer built last night and will test the vacuum at the oil fill tube tonight to assess my AOS. Then we'll see what the next steps might be.
Car still drives well and sounds good. Just the occasional white cloud at start up consistent with shut down of a cold motor.
06-27-2017, 12:01 PM
#35
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That is some excessive consumption. The AOS breather connection is on Bank 2, right side of engine, which is the drivers side (left) tailpipe. Sounds like you are on the right track.
06-27-2017, 12:08 PM
#36
Can you open the coolant cap and check if the coolant is clear? Does the car make any tapping noise at idle after fully warmed up? It sounds like a mechanical problem (rings, bore scoring) in bank 2.
06-27-2017, 12:25 PM
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^^ I didn't want to go there yet but that's what I was also thinking. Next up should be compression/leak down tests on Bank 2, and maybe boroscope while in there. You can also drop the oil sump plate and inspect the cylinder bores that way. While the spark plugs are out inspect those as well. A lot can be determined by how the spark plugs look.
06-27-2017, 12:29 PM
#38
I'd pull an oil sample & get analysis. You can have at least a portion of the cylinder walls checked with the plugs out for a few hundred bucks of labor. A compression test may show a red flag. Overall though, the more data points you get the better informed you'll be. Good luck going forward.
06-27-2017, 01:13 PM
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Yep. This morning I opened and used a pipette to remove some since I can't see worth crap inside that tank in the engine bay. I did this to verify what color coolant I had (no idea when it was changed last and I wanted to be ready with coolant should I need it). The color that I sucked out was light orange/pink, with no emulsification or particles in it. So I think it qualifies as clear. Prior to withdrawing the sample I used the pipette to "stir" the tank to see if there was sediment or localized concentrations so I could get a good sample. Not a end-all-be-all conclusive test but best I could do this morning to assess. I will repeat again though a few time over the next several days.
06-27-2017, 01:40 PM
#42
He thinks your engine needs to be rebuilt on some level. Based on the consumption level & tailpipe soot, it could be a good idea for you to try and get a different data point or two that will reinforce or disprove the theory that your car has some scoring issue that's caused a cylinder to consume oil at a rate far above what regular specs allow.
My suggestions are an attempt to try and verify the scoring theory. A borescope could help and high deposits of cylinder lining material in your used oil sample would corroborate this & give you enough confidence in the diagnosis to pull the trigger on some type of remediation. It may be a case where you can continue to drive the car, but doing so puts the engine case at risk of a more serious failure downstream.
If I were you I'd get in touch with a good indy and/or start investigating re-sleeving options for the cylinders.
My suggestions are an attempt to try and verify the scoring theory. A borescope could help and high deposits of cylinder lining material in your used oil sample would corroborate this & give you enough confidence in the diagnosis to pull the trigger on some type of remediation. It may be a case where you can continue to drive the car, but doing so puts the engine case at risk of a more serious failure downstream.
If I were you I'd get in touch with a good indy and/or start investigating re-sleeving options for the cylinders.
06-27-2017, 01:56 PM
#43
At the rate of consumption either the AOS is shot but in that case you would have massive amounts of smoke at startup. So my money is on a scored cylinder or multiple cylinders with a decent amount of blow by causing you to consume oil at a rapid rate.
I think she's got to come apart and have a rebuild to one degree or another.
I think she's got to come apart and have a rebuild to one degree or another.
06-28-2017, 10:45 AM
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Update 6-27-2017: Coolant appears to be holding level. Based on the dipstick and measuring it cold on a flat surface in the AM before starting the engine, it appears the car has consumed about 1.5 qts of oil in 200 miles. This is on pace to equal what I previously thought was 4+ qts missing. The soot has re-appeared on the driver side tailpipe. I'm going to call this excessive since I do and intend to drive this more or less daily (the last 2 weeks had some off days). My commute is a mix of stop/go surface traffic, winding back roads, and interstate highway. I try to exercise the car as that is why I bought it.
I finally got my homemade manometer built last night and will test the vacuum at the oil fill tube tonight to assess my AOS. Then we'll see what the next steps might be.
Car still drives well and sounds good. Just the occasional white cloud at start up consistent with shut down of a cold motor.
I finally got my homemade manometer built last night and will test the vacuum at the oil fill tube tonight to assess my AOS. Then we'll see what the next steps might be.
Car still drives well and sounds good. Just the occasional white cloud at start up consistent with shut down of a cold motor.
With engine cold, just started I measured a crank cave vacuum using a water manometer at the oil fill tube of 4-5 inches water. The engine was having some trouble adjusting to me taking the cap on and off multiple times as I set up for the measurement, hence the range in measurement.
After a 20 mile drive and the engine temp at my normal of the right hand edge of the "8", and after many curious looks in the Wawa parking lot I measured 4" of water vacuum.
Based on my limited knowledge, this does not indicate an AOS problem at this moment (realizing it might change). This values are in teh "normal" range. Dissappointing. I'm probably the only person on this forum hoping for AOS failure. Well not really.
There is a mechanical tapping sound. I took video of it with the engine idling cold just after start up and hot after the 20 mile drive. I am in the process of trying to convert it to a supported file format. It may have to wait until I get home from work though. I do need to add that when I first got the car I had it checked out by a local indy shop, and they found what they thought was a sticking lifter (not sure which one), and they added an additive to the oil to boost it. I believe the sound they heard and what I hear are one and the same. If you close your eyes and imagine, the sound is a steady tick-tick-tick-tick.
