B8.5 S4 Oil leak

[blueline004]

I'm about 5k in trying to find an oil leak.
I get a small drip when running the engine only. I go through about a quart a month.

We have replaced the rear main seal, sealed the timing chain covers and oil pan, replaced the oil cooler, valve cover gaskets. And the oil filter housing. Suggested by the dealer.

No luck.
PVC valve was fine btw.

Is it possible there's a leak in the engine block?
Or a hose? What could I be missing?

Any help would be appreciated!
Thanks!

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[Nillious]

I usually hate answers like this, but if I paid a dealer that much money to fix an oil leak and it was not fixed afterwards I’d be having a talk with them it. If you paid them to fix it and they didn’t then they need to find the problem and make it right.

Have you spoke with them about this?

[SwankPeRFection]

Are you seeing an actual small drip somewhere and if so where exactly? Or are you just losing oil somehow and thinking it’s dripping somewhere. Hard to believe you’re seeing a drip since the bottom cover would catch it no matter where it is. About the only actual oil looking drip you’d see make it past that cover isn’t even an engine oil drip, it’s when the engine mounts crack and the fluid inside them drip, but that’s going to be an all black liquid.

[blueline004]

That's a fair response.

I've been going to a small repair shop. I paid the dealer about 280 to diagnose the problem. They said the work that had been done was nicely done, but the leak was from the oil filter housing. They wanted over 1000 for a 50.00 part, so I bought one myself and took it back to the original shop. They replaced it for me ( no charge). But I'm still getting the leak. I mean I guess I have a legal case against the shop, but I really don't want to go after him for money. I just want to find the leak.

I just thought maybe someone on this forum might have some experience with this.

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[SwankPeRFection]

OK, so if it’s leaking from the oil filter housing, was your replacement a proper Audi part or some aftermarket OE one? Also, the filter housing (when changing filters) has TWO seals that need to be replaced. There is one deep inside the cap itself which gets pulled out after the old filter is pulled out of it and before the new one is inserted into the cap. The second thinner seal is at the top lip of the oil filter housing that’s on the engine side. This is the one that’s sometimes missed or not installed at all and it would lead to a leak from the housing threads.

With the engine running, feel around the oil filter housing lid towards the top where the threads are and see if it’s leaking there. If you don’t feel or see any oil on your fingers, then your leak is happening from the bottom where the housing connects to the engine and that could be a missed oring that wasn’t installed when they replaced the housing or something else there.

All that said have you actually looked at the issue yourself or are you like taking someone else’s word for it? Open the hood and check.

[freshjive]

So where does the oil leak look like its coming from? where were you told it was coming from?
Has uv dye been put in the oil the help pinpoint where its coming from?
You had the dealer diagnose the problem but went to a repair shop for all the work and it still leaking? Did the shop replace the oil filter housing or did they say they did?

Regardless I would be taking it back to the shop thats been doing all the work to verify where its leaking from before spending any more money or take it to another shop that will fix the problem.

[Nillious]

Get some UV additive and a light. put the additive in your oil. Drive for a day or two. Pull both belly pans and get the car on jack stands. You will have a nice trail of glowing oil under the light. I’ve used this to trace ac leaks and it works great. Literally points you directly to the leak.

[Fresh.S4]

OK, so if it’s leaking from the oil filter housing, was your replacement a proper Audi part or some aftermarket OE one? Also, the filter housing (when changing filters) has TWO seals that need to be replaced. There is one deep inside the cap itself which gets pulled out after the old filter is pulled out of it and before the new one is inserted into the cap. The second thinner seal is at the top lip of the oil filter housing that’s on the engine side. This is the one that’s sometimes missed or not installed at all and it would lead to a leak from the housing threads.

With the engine running, feel around the oil filter housing lid towards the top where the threads are and see if it’s leaking there. If you don’t feel or see any oil on your fingers, then your leak is happening from the bottom where the housing connects to the engine and that could be a missed oring that wasn’t installed when they replaced the housing or something else there.

All that said have you actually looked at the issue yourself or are you like taking someone else’s word for it? Open the hood and check.

I replaced my oil housing with a URO brand and all seems to be holding up just fine (for now lol). initially i was worried it was my timing covers, but once i pulled the oil housing off, it really looked like my wiener looking gasket was the culprit. with a good flashlight and a keen eye you can visually see that mounting area for leaks.

Get some UV additive and a light. put the additive in your oil. Drive for a day or two. Pull both belly pans and get the car on jack stands. You will have a nice trail of glowing oil under the light. I’ve used this to trace ac leaks and it works great. Literally points you directly to the leak.

reminder, if someone goes the UV method, clean all around all of the oil residue from the whole engine (or at least in the suspected area) so you can clearly identify where a leak might be coming from.

and remember oil drips are gravity fed, so always start from the top and inspect downward.

[SteveYem]

I wonder if I'm about to head down this same path. 2015 B8.5 S4 6MT with 99k miles on the clock. For the past couple thousand miles I've been noticing an oil burning smell when stopped in traffic and when I get out of the car after a drive, but only last week did I start seeing a small amount of oil precipitated onto the driveway. The oil leak does not seem to be active when the car is turned off. As soon as I start the car, I see oil dripping out of the belly pan onto the driveway. I'm not sure whether the leak is triggered by pressurization of the oil system, or rotation of the crankshaft (i.e. rear main seal). I looked and felt around the oil filter housing while the engine was idling, hoping to find the leak there, but no luck. I have an appointment to take the car in to the local trusted independent shop this week, and will make sure to have extra motor oil on hand in case the thing starts to let loose during the 10 mile drive to the shop, but I suppose in the meantime I'm trying to prepare my b-hole for what the diagnosis will be.

[BrokeBichB8]

PCV can be in tact and have good gaskets and rubber components visually but can have bad venting components and be filled with sludge that will ruin it. Positive pressure build up pushes oil past seals

[SteveYem]

While I'm not the OP, I'm following up on this to say that my oil leak was found to be from the valve cover gaskets. I had them replaced on both sides and there is no more leak. Similar to the OP, the oil leak was only active while the engine was running.