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First off this is for my 09 997.2 C2 with PDK.
Went to check my oil yesterday after a longer spirited drive and was originally down 3 bars on the oil reading ( filled it to the top of the reading ). The car has almost 96,000 miles, oil was changed about 1500 miles ago with a 5w-40 LM ( live in ohio ). The car is really only used for spirited driving and isn't taken out unless it's going to be used at operating temp for awhile. After getting home and letting the car cool down from 210 to about 150 on the oil temp I took another reading in my garage ( very flat ) and was down 2 bars. I have spent the past day or so reading about oil consumption and its honestly all over the board. Some say a DFI will have a ton of soot on the tail pipe, which mine does and will burn some oil and others say there car has never burned oil and if it's burning any sort of oil its an issue.
Reasons I think it's the AOS:
* Start up has been rougher ( fighting a battery issue so overlooked this a tad )
* Idle at start seems to be more sporadic, before it would start at around 1100 or so for 5-10 seconds and then drop now it does the bouncing up and down a bit.
* A few days ago there was white smoke out the back, I assumed it was because the car sat for two weeks and it was in the 30's but after it did it again after sitting for 3 days and it was about 45 degrees out I started to think I might be overlooking something.
* Oil spots on bumper
* At times when driving hard seems like there could be a slight burning smell ( after covid I never got my sense of smell back so I am not 100% on this one )
if I'm doing the AOS is there anything else I should do while I am in there? This car is going to be driven hard this year.
Still need to do plugs and coils but don't want to do that until the possible AOS/burning oil is figured out.
Also should I run something through the fuel/oil to clean things up? If so what is the bee's knees or the cats meow of the fuel/oil cleaning world?
Was planning a drive today but don't want to do an damage with another spirited drive.
Have you checked your crankcase vacuum level? I built a cheapy water column manometer out of clear tubing, backer board, and a yardstick, and then modified an extra oil filler cap with a nipple. My 2005 997.1 C2S is suggested to have 4-6 inches of water.
I have not, I heard about using a manometer but if I was gonna buy one it was half the price of a new AOS. How did you make yours/how is it supposed to be used?
I think the only useful test is the manometer test. Note that the crankcase vacuum on the 997.2 is higher than the 997.1 so don't use the 997.1 spec: if you do a search there are details out there on what it should be. You can get a cheap digital manometer for $35 on Amazon but you'd also need to get an oil cap to modify (or just some way to seal the oil cap area and add a nipple).
Given your symptoms it wouldn't be crazy to just try replacing it and seeing if that fixes the problem. The 997.2 AOS is supposed to be more reliable than the earlier ones but it can still fail.
I suspect your car is fine. I think what you did was give it an Italian Tuneup.... casually driving this car is not good for it and fouls plugs... I know this because one time before a plug change (I DIY) I had a short commute to a train station and my plugs looked like hell and I could cause carbon flakes to come off of them by banging them on the table. Yes, it could be a failed AOS, but those are pretty rare in the .2 model. Those spots on your bumper... are you sure they are oil and not carbon being blown out with the water in your exhaust?
It defiantly could be a failed AOS. One way to test the AOS is to start the engine and remove the oil fill cap... if it is being sucked down onto the tube, that is a failed AOS. A manometer is the other best way.
BTW, I think changing your coils at 100K is OK although I got about 175K out of mine.
Peace
Bruce in Philly (now Atlanta)
Last edited by Bruce In Philly; 04-07-2024 at 02:34 PM.
Have you checked your crankcase vacuum level? I built a cheapy water column manometer out of clear tubing, backer board, and a yardstick, and then modified an extra oil filler cap with a nipple. My 2005 997.1 C2S is suggested to have 4-6 inches of water.
I guess you are right, it could be carbon. It isn't oily, very dry almost like chalk, same as the exhaust tips. The car is white so every little spec is able to be seen. How much water comes out after sitting? Lately the car doesn't sit more then 4-5 days and with the weather finally turning it will hopefully get driven every few days.
The only reason I mentioned the coils is due to indy that did the PPI said they should be changed since they look like the originals. The guy said he has never seen original's run to 90k but he has been wrong with 5 or so other items so I don't have the greatest confidence in him.
Would there be a significant amount of sucking via the fill tube, similar to if you put your hand over a vacuum tube or something like that?
...Would there be a significant amount of sucking via the fill tube, similar to if you put your hand over a vacuum tube or something like that?
Yes, there would be significant crankcase vacuum if the AOS is completely ruptured. Definitely would be able to be felt with your hand at the oil fill tube. Less than complete ruptures would likely need the assistance of a manometer to assess.
To build the water column manometer, take a 1x3x5ft backer board and attach a yardstick. Then using round staples, attach the clear tubing as shown in my pic here. Fill the tube with food-colored water. Mark where the water level is. Start your already hot engine. Use the modified oil fill cap. Connect the clear tubing end to the oil fill cap. Measure the distance between the high and low water levels. Compare this value to the 997.2 spec.
Have you checked your crankcase vacuum level? I built a cheapy water column manometer out of clear tubing, backer board, and a yardstick, and then modified an extra oil filler cap with a nipple. My 2005 997.1 C2S is suggested to have 4-6 inches of water.
If I can trust my Google-fu a 997.2 should have 14-16 in-H20 vacuum in the crankcase. So if you DIY your own manometer make sure you make it big enough or you're going to suck the water into the engine. Like, if somethings *really* wrong and you have a lot more vacuum than that, for example.
Were it me I'd just spend the $35 and get the digital one on Amazon (or just put the $35 towards a new AOS, I guess).
Just started the car hadn't been driven in 5/6 hours, had the misses start the car while I held my hand over the filler cap and at first there was no vacuum but after a few seconds it started to suck. When I removed my hand it made the exact same noise you would hear if you put your hand over the vacuum, seemed to be pretty strong suction but don't really have much to go off of to compare, if anyone would like to test there and report back that would be more than welcome.
Looks like an AOS might be in the future, is it recommended to order the "kit" with all the tubes or will the AOS it self suffice?
If I can trust my Google-fu a 997.2 should have 14-16 in-H20 vacuum in the crankcase. So if you DIY your own manometer make sure you make it big enough or you're going to suck the water into the engine. Like, if somethings *really* wrong and you have a lot more vacuum than that, for example.
Were it me I'd just spend the $35 and get the digital one on Amazon (or just put the $35 towards a new AOS, I guess).
Good point. I forgot to mention that to avoid (and you MUST avoid) sucking water into the engine (possible hydrolock}, slowly engage the clear tubing on the nipple and watch the water level to be sure you are not going to pull the water out of the tube.
Just started the car hadn't been driven in 5/6 hours, had the misses start the car while I held my hand over the filler cap and at first there was no vacuum but after a few seconds it started to suck. When I removed my hand it made the exact same noise you would hear if you put your hand over the vacuum, seemed to be pretty strong suction but don't really have much to go off of to compare, if anyone would like to test there and report back that would be more than welcome.
Looks like an AOS might be in the future, is it recommended to order the "kit" with all the tubes or will the AOS it self suffice?
thanks to all those who have helped
Replace the tubes. There's no doubt at least one will break, which is better than a partial small break that creates a vacuum leak.
04-07-2024, 01:46 PM
997.2 AOS/Hard Driving or Both?
