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Short update: I suspected that the aftermarket part (Vaico - PCV valve) even though it looked to be brand new, might not work properly, and it looked like it was stuck open. It seems like it happens quite often for an aftermarket PCV valve not to perform as well as an original part so I guess the solution here might be to replace it with an original part. However, it looks like one can not order only the original PCV valve but has to order the entire valve cover which costs about 7-800 € and it takes forever to be delivered. So I thought it wouldn't harm to give it one more try with an aftermarket part so went for a Febi Bilstein valve cover. After installing the new valve cover the car ran for over 30 minutes perfectly, the engine was just purring, and almost no smoke at all but after that, it started to run again like crap, and of course, after checking the PCV hose, some oil was coming out of it again... So I really don't think this would have anything to do with valve seals or anything like that. The car starts running like crap after the PCV valve covers everything in oil, from intake to spark plugs and so on. Oil would not get from the valve seals into the air filter housing. Here I suspect of course just the PCV valve which would be stuck open and let lots of oil vapors which later will condensate into the much cooler intake. Why an aftermarket part would perform so much worse than an original part, I don't know. An external PCV valve and catch-can will also be considered but it doesn't look ideal to me.
Update: I took it to a 3rd shop today for diagnosis.
They tested crankcase pressure and said it was spot on. They removed the o2 sensor on the exhaust and looked up at the cylinder. They said they could see oil dripping on cylinder 1.
Based on the symptoms, his conclusion was valve seal on cylinder 1. However he still was not sure about oil getting all the way back to the air box… that would point to a PCV.
I think I’m going to try out some different seal conditioners. ANY RECOMMENDATIONS?
I also think I’ll still install the catch can, just in case it is randomly dumping from the PCV and seems like a good option for direct injection engines anyways.
I will update on any success with oil additives.
Sorry but I don't get it. If you'd remove the O2 sensor you would be able to look at the exhaust ports at the most, not the cylinders. I would look into the cylinder through the spark plug hole or so. And then maybe there was oil dripping into the cylinder because the valve may not have been seated fully and there was oil into the intake port. The first time we removed the intake there was a puddle of oil on most of the closed valves and of course, there was no oil or there was dripping oil into the cylinders there were the valves were open or partly opened. And so much oil was not dripping past the valve seals for sure. There was no oil to be seen dripping from the valve guide/seal either. I would rather make sure not to book a big job like replacing all the valve seals, if not explained firstly why so much oil was found in the intake manifold, air filter housing, and so on. From my point of view, the problem would be a stuck open PCV valve. Why's that when compression, crankcase pressure, and everything else looks absolutely normal? That's an answer I'm looking for too. Maybe the issue here is indeed the bad after-market parts. Did not test all of them, some of them might be fine, and some of them might not. Or maybe someone else would have a clue about what's going on here.
P.S. They might've looked at the exhaust port corresponding to cylinder 1 and seen oil dripping from the valve seal/valve guide on to the valve > cylinder. But I still don't see the possibility for this oil (which I don't really believe could be that bad of a leak) to get all the way to the air filter housing. That could've been caused only by the PCV valve imo.
Last edited by mariusmight; 06-18-2024 at 07:23 PM.
Short update: I suspected that the aftermarket part (Vaico - PCV valve) even though it looked to be brand new, might not work properly, and it looked like it was stuck open. It seems like it happens quite often for an aftermarket PCV valve not to perform as well as an original part so I guess the solution here might be to replace it with an original part. However, it looks like one can not order only the original PCV valve but has to order the entire valve cover which costs about 7-800 € and it takes forever to be delivered. So I thought it wouldn't harm to give it one more try with an aftermarket part so went for a Febi Bilstein valve cover. After installing the new valve cover the car ran for over 30 minutes perfectly, the engine was just purring, and almost no smoke at all but after that, it started to run again like crap, and of course, after checking the PCV hose, some oil was coming out of it again... So I really don't think this would have anything to do with valve seals or anything like that. The car starts running like crap after the PCV valve covers everything in oil, from intake to spark plugs and so on. Oil would not get from the valve seals into the air filter housing. Here I suspect of course just the PCV valve which would be stuck open and let lots of oil vapors which later will condensate into the much cooler intake. Why an aftermarket part would perform so much worse than an original part, I don't know. An external PCV valve and catch-can will also be considered but it doesn't look ideal to me.
I did try the external PCV, so far its working great!
why are you hesitant?
I have the exact same issue just this week. Replaced new intake manifold, covers and hoses etc, short of doing an overhaul with new pistons, conrods or replace a new engine block. Mech suggested replacing this vacuum pump, he thinks this could be the source of the problem.
Mech suggested to replace this part
Last edited by Adrian Chay; 07-20-2024 at 07:14 AM.
....and I get a low oil warning. Granted, we do drive this car a lot—probably 5k miles before the light comes on. I add a quart of oil, and I’m back on my way!...
Three months later, I’m back at oil minimum, again probably 5-10k miles. The same mechanic says we might have an issue and to add another quart.
A few more months pass and a few thousand miles, and we’re back to oil minimum. The mechanic says it’s likely the PCV valve, so we get the whole PCV unit replaced (it’s all one piece with the valve cover) along with an oil change.
I do not see an issue with oil consumption of 1 qt per 5,000-10,000 miles. What oil brand/name and weight are you using? At 10k miles you should be doing an oil change instead of adding a quart.
It sounds like you do not try to fill the oil to the top bar (full). Just add a quart when the oil level message comes on and it will level below the top bar line. That is what I do.
Originally Posted by jpooley
Mechanic said there was strangely NO pressure in the crankcase. I’m not sure how he tested that though… How can I look for blockage? Would I have to remove the valve cover PCV unit to check?
Do you have any codes?
Watch this video to double check that all of the lines were reattached AND seated properly. He also identifies a simple test of the PCV/AOS near the start of the video.
Find a mechanic who knows how to test Cayenne crankcase pressures using a manometer...or better yet, make your own and test. Report back with the result.
Make your own:
- Buy a new Porche branded oil filler cap, install it on the engine and use the leftover one to build the test port
- Take said oil filler cap and install a brass nipple fitting to match the manometer's hose size. Install the nipple with some engine rated rtv.
- Buy a 2 port digital manometer on amazon. < $35.
06-18-2024, 06:46 PM
