When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Having recently replaced my PCV diaphragm and cap with a new quality part, I've now started to chase down other issues with the engine on my newly purchased project CTT.
There seemed to be an oil leak originating from the little tube connected to the bottom of the intake pipe that leads into the throttle body. After a few hard accelerations you could see where oil had been spraying out of what appears to be this location. A large ammount of old greasy oil residue around this area seemed to confirm this is the source of a leak. Is this a common leak, and what parts will I require to prevent it?
I decided to pull off the air intake pipe to take a look at the throttle body and the other surrounding areas. There was quite a lot of oil in these pipes and the throttle body itself, mostly originating from the right hand side intake pipe. From what I've read this is normal due to the poor PCV design which dumps the oil vapours back into the intake pipe on this side? Is there anything I should be doing to prevent large ammounts of oil getting sucked into the intake system or is this something that occurs by design?
Lastly, upon removing the splash shields underneath there are more signs of leaking oil, predominantly from, you guessed it, the right hand side. Maybe this is just runoff from the old broken PCV valve but it looks a little worse than that. Can anyone with experience with these engines advise what the likely cause would be? There was also a small ammount of oil on the left side, but nothing particularly noteworthy.
Is anyone able to offer some advice on where the best place to start is in order to put a stop to these leaks and any other potentially troublesome PCV system issues that need to be addressed. I want to focus on getting this engine running perfectly before I start tackling other jobs such as general deffered maintenance, replacing the gearbox valve body and fitting a new park brake cable.
TIA
That hose in the second picture is a line that goes to the brake booster, so oil is not coming from that line.
The PCV dumps oil into the driver's side turbo intake, left side of the car facing forward. That is likely where the oil in the intake is coming from. Some people recommend installing a catch can system to trap the oil blowby. There are posts on this forum about installing a catch can.
The oil on the right side hoses next to the transmission cooler "S" hoses is probably from a leaking valve cover gasket. Oil on the outside of the left side boost hoses and diverter valve is probably from leaking valve cover gaskets too. They leak profusely especially as they get old and harden. I have put a set of new ones in my Cayenne and I cross my fingers they stop the oil leaking..... the built up oil and grime on my engine was over an inch thick around the A/C compressor and on top of the alternator.
That hose in the second picture is a line that goes to the brake booster, so oil is not coming from that line.
The PCV dumps oil into the driver's side turbo intake, left side of the car facing forward. That is likely where the oil in the intake is coming from. Some people recommend installing a catch can system to trap the oil blowby. There are posts on this forum about installing a catch can.
The oil on the right side hoses next to the transmission cooler "S" hoses is probably from a leaking valve cover gasket. Oil on the outside of the left side boost hoses and diverter valve is probably from leaking valve cover gaskets too. They leak profusely especially as they get old and harden. I have put a set of new ones in my Cayenne and I cross my fingers they stop the oil leaking..... the built up oil and grime on my engine was over an inch thick around the A/C compressor and on top of the alternator.
Thanks for the reply.
I guess the source of the oil is either the seal around where the Y pipe connects to the throttle body, or it's being sprayed out of that fitting that connects to the brake booster, but originating from the intake pipe? Can this be prevented by draining that intercooler pipe which people speak of on the side where the PCV dumps oil back in?
A catch can would obviously be a better long term solution but if draining the oil from the intercooler charge pipe will prevent it spraying everywhere then I'd rather do that, at least if it lasts for a while before filling up again.
New valve covr gaskets will be on the to do list. Are they ones that require a special installation with sealant or you just install them and put the covers back on?
I guess the source of the oil is either the seal around where the Y pipe connects to the throttle body, or it's being sprayed out of that fitting that connects to the brake booster, but originating from the intake pipe? Can this be prevented by draining that intercooler pipe which people speak of on the side where the PCV dumps oil back in?
A catch can would obviously be a better long term solution but if draining the oil from the intercooler charge pipe will prevent it spraying everywhere then I'd rather do that, at least if it lasts for a while before filling up again.
New valve covr gaskets will be on the to do list. Are they ones that require a special installation with sealant or you just install them and put the covers back on?
Cheers
Little bit of sealant where the timing cover meets block meets valve cover
Today I drained the oil out of my intercooler charge pipe that the PCV connects to, there was quite a lot in there. Now that this is drained and the PCV diaphragm has been replaced the smoking I was getting before seems to have stopped which is great.
After another drive though there still seems to be oil splashing out from somewhere underneath the intake Y pipe. That little tube I posted a photo of does indeed look like the source, but if it's a brake booster line surely that's not right...
Any ideas as to what else in this vicinity would cause all to splash up as pictured?
When I removed everything before that little pipe is the only location that I could see that looked like it was leaking oil.
Look at the plastic Y plenum carefully. It may have hairline cracks in it that under boost pressure are blowing out the oil as they all crack with age and why I replaced mine with a metal ipd plenum. If the intercooler is thoroughly clean and emptied, I'd say that dirty looking oil is coming from engine blowby or a worn turbo, but haven't seen too many failed turbos but spitting out through a crack in that plenum. A smoke test of the intake might highlight where the leak source is, but it also may only do it under boost when the crack is forced open. It may also take some time to get the accumulated oil from the intercooler being full out of the rest of the system.
It seems to me that either there is still oil in the intake piping or the seals on the front timing cover are leaking.
That small nylon line leads to the brake booster venturi system which is located behind the right hand SAI blower. I suppose it's possible that oil got pulled into that line from the Y-pipe and is now getting pulled out. That line runs aft just above the fuel injectors on the right hand side of the engine.
When I drained the left hand boost pipe I got about 14 ounces of oil. After that I removed the intercooler and rinsed it out with gasoline. I'd bet there were 4 more ounces of oil spread out inside the intercooler.
I only drained the pipe and not the intercooler itself so perhaps I should do that and see if the oil splashing continues. There is no evidence to suggest the belt is kicking oil up, the oil cooler looks dry from the underside so no leaks from there it seems. Engine blowby or worn turbos are a possibility given the high mileage (over 190,000) but it does seem to pull well on boost so nothing seems majorly wrong or aged in that regard.
Hairline cracks in the intake Y pipe seem likely, and the issue does only seem to present itself when under boost so this would back this theory up. It would not surprise me if the front timing cover was leaking, although I'd expect this just to run down the side of the block and build up sludge rather than spray out?
Ideally the engine probably needs to come out to sort every leak, damaged seal and gasket, etc, however for now I'm looking to get the car into the best possible state I can without spending $$$$$. If I decide it's a keeper down the track then maybe I'll give it some more love.
You need to remove the intercooler itself and empty it. That's where the oil is actually coming from.
Is it accessible through the fender liner with the belly pan removed or does it require removal of the front bumper? Can't find any videos on youtube which seems to be a running theme with this car. I would've expected more people to be making DIY's on them. I guess most people buying Porsche's don't work on them themselves.
Why you remove the y plenum, how do you disconnect from this piece? It's locked on and requires like a fuel disconnect tool to get them apart. If you're just pulling it off, then you have an issue right there.
To remove the Y plenum there are two plastic screw lock mechanisms on either side, much like you have to remove to take out the airboxes on either side. Should there be something else?
As far as I can tell the zip ties are simply to prevent it from contacting with the belts or pulleys and stop the hoses from flapping about.
10-18-2022, 06:28 AM
Oil leaks and PCV system
