Oil in coolant

[Homer_J]

Background: So I've had a problem for almost a year with coolant disappearing. Didn't appear to be in the oil, no obvious puddles underneath. It seemed to be much worse in the winter so I assumed heater core, and I've just been putting off digging in there for a leak and topping it off when necessary.

Yesterday: I got the low coolant warning, which I hadn't had in a couple months. Not very surprised, I popped the hood to add more. There was about an inch of oil floating on top of the remaining coolant in the reservoir. Looking for ideas on the cause. I'd typically think bad head gasket, but I had my pistons replaced about a year ago, so I'm hoping that should still be in good shape. (Also I thought bad HG would usually result in coolant flowing into oil, not the reverse?) I think the older gen a4's had an oil cooler that would develop a leak into the coolant, do we have one?

Anyways, don't know if the leak and the oil are related, so mainly interested in fixing the oil problem. (I disconnected the reservoir, dumped it out, and topped it off.)




Couldn't find much evidence of leaks. There is a pink splotch baked onto a pipe just behind the engine on the passenger side. (The catalytic converter is the piece at the bottom of the pic)

[Zach L]

Heat exchanger or head gasket.

[van462]

If you have an automatic could the oil be transmission fluid vs engine oil. They share the same radiator.

[Homer_J]

Alright been out of town for a few days, now I can get back to troubleshooting. Thanks for the ideas guys, I'm not sure where to start since all these potential leak points are internal and can't be seen. I guess I'll get underneath today and see what I can see Of course my intake manifold decided to go today too, when it rains it pours.

Heat exchanger or head gasket.

Alright thanks, I found the oil cooler in the manuals. I guess if I did that I might as well go crazy and replace the water pump and thermostat, since the coolant needs to be drained etc.

If you have an automatic could the oil be transmission fluid vs engine oil. They share the same radiator.

Interesting point, yea I just assumed oil. Trans fluid is probably blacker than the oil after 123k miles.

[JD23]

Don't worry, Audi states that the transmission fluid is "lifetime fluid". It will surely look pristine after infinite miles.

[lettuce]

Don't worry, Audi states that the transmission fluid is "lifetime fluid". It will surely look pristine after infinite miles.

Audi denotes their parts as 'lifetime' based on how long they will last in relation to the car's lifetime. If the transmission blows up, the car is dead. The transmission fluid lasted the lifetime of the car. Bam, lifetime fluid.

Just like how my 'lifetime' balance shaft gear lasted the entire life of my engine.



Jokes aside, I just had my radiator completely disconnected which involved removing the transmission cooler lines, and the transmission fluid that seeped out looked fairly translucent with 125K on the motor/trans. If it's that dark I'd lean towards engine oil.

We do have an oil cooler that uses the coolant to cool the oil. It's attached to the oil filter housing/accessory bracket. I had that off as well and swapped it out with a newer one. I didn't really see any way it could break causing the two to mix.

If you recently had your head off, which would have happened when doing the oil consumption fix at the dealer, any number of things could have gone wrong. Namely not torquing the head bolts down properly which is needed to seal/compress the head gasket down between the block and the head. You say you developed your issue with missing coolant around a year ago, which is also around the time you say you had this fix done. That's the first thing I would suspect. Dealership mechanics are far from infallible.

[Homer_J]

We do have an oil cooler that uses the coolant to cool the oil. It's attached to the oil filter housing/accessory bracket. I had that off as well and swapped it out with a newer one. I didn't really see any way it could break causing the two to mix.

If you recently had your head off, which would have happened when doing the oil consumption fix at the dealer, any number of things could have gone wrong. Namely not torquing the head bolts down properly which is needed to seal/compress the head gasket down between the block and the head. You say you developed your issue with missing coolant around a year ago, which is also around the time you say you had this fix done. That's the first thing I would suspect. Dealership mechanics are far from infallible.

I agree that it's a possibility. However I've lost many quarts of coolant and have had no evidence of coolant in the oil or smoke out the exhaust (but no puddles either. A slow drip near the exhaust could result in quick evaporation maybe). And the oil issue just started... I don't think an internal leak in the oil cooler is unheard of, which would mix the fluids. I suppose part of me is just hoping that it's not the HG because I don't want that headache.




I couldn't find evidence of anything obvious. Its hard to tell where the leak on the rear passenger side of the engine is coming from. I'm guessing it must drip/run out of the flange that comes right out the back of the block and pipes to the heater core. As far as the dark fluid in the reservoir issue goes...couldn't find anything. Some threads from previous gen audi's seems to indicate if oil is getting into coolant=bad oil cooler, and if coolant gets into oil=bad head gasket. But who knows. (Hoping it's not transmission fluid)

Now I need a new intake manifold, so I can't even really drive the car. I'd be tempted to replace the manifold and then wait and see how bad the oil issue is, but I feel like replacing the oil cooler is way easier with the manifold off, and I don't want to take it off twice
...And since I'm in there, I might as well swap out the water pump since I don't know if it's ever been done. If anyone has any other suggestions, I'm all ears.

Is there anything else I should purchase if I do this job? Maybe I'll make a big ECS order in the morning.

Shopping List:

-Intake Manifold w/ gaskets
-BG Induction system cleaner to clean carbon off valves
-4 fuel injector O-rings

-Oil Cooler
-Oil Cooler gasket
-Water pump incl. thermostat and new bolts
-New water pump belt
-Big jug o' coolant (g12++ or g13?)
-New coolant hose flange for rear of engine block

[jfo]

A shop can check for the presence of combustion gases in the coolant...either hydrocarbons or CO, which would indicate a HG leak. If they are absent it is likely oil from the oil cooler. I'm unfamiliar with the oil cooler on our engine, however I had this problem on my last Volvo, with the oil cooler on the rad failing and allowing oil to enter the cooling system. It may be unrelated to your loss of coolant, which could be a small leak that evaporates as you drive.
If you have oil in the cooling system, I would flush the system well with water and then coolant blend, to remove any residual oil from the small oil ports/channels after you have fixed the source of the problem. Even with flushing you may see continue to see small amounts of oil floating in the coolant tank. I just kept drawing the top layer of oil/coolant off with a syringe until it was finally clean.

Edit: You may want to check the turbo coolant line connections for leaks, since you noted pink residue on that side of the engine.

[Homer_J]

Copy all of that, thanks. I'll check into the turbo lines. Arg i need a good hand mirror to see all of this stuff.

[jfo]

Copy all of that, thanks. I'll check into the turbo lines. Arg i need a good hand mirror to see all of this stuff.

A extending, adjustable mirror is very useful! I also have an inspection camera that has helped zoom in to hidden areas and look for leaks, hidden fasteners, etc. I believe some members here have tried this cheap camera or one like it that works with a non-Apple phone.
http://www.lightinthebox.com/720p-hd...ml?prm=1.2.1.0

[Crucible35]

Do you hear any sloshing/flow of water behind the dash....after I had my pistons and rings done on my 09 A4, turned out there was a hole in the cylinder (likely from the work done) that was leaking coolant into the cylinder from the water jacket. Took forever to find/diagnose the issue with the dealer...but I took it to an independent who drained everything and put a camera into the cylinder. When they put water back into the cooling system while the camera was in Cylinder 3, they could clearly see the water flowing right into the cylinder. Only option was to replace the block.... but I traded her in instead.

[Homer_J]

Do you hear any sloshing/flow of water behind the dash....after I had my pistons and rings done on my 09 A4, turned out there was a hole in the cylinder (likely from the work done) that was leaking coolant into the cylinder from the water jacket. Took forever to find/diagnose the issue with the dealer...but I took it to an independent who drained everything and put a camera into the cylinder. When they put water back into the cooling system while the camera was in Cylinder 3, they could clearly see the water flowing right into the cylinder. Only option was to replace the block.... but I traded her in instead.

Hmm I do actually. Seems like more in the cooler months which was leading me to believe the heater core was draining and I'd hear it sloshing for a min on cold starts. Did you blow a bunch of white smoke upon startup? (I don't, it just seems like you would)

Edit: and that's terrifying

[Homer_J]

Just a little update... Turns out that the coolant flange on the back of the head was leaking. I'm hoping that it's the only leak (and hopefully that's why my heater core gurgles sometimes) I think it was actually cracked, so when I removed it part of it stayed in the head. (see pics) Hopefully that solves the disappearing coolant issue anyway. I've gotten just about everything off, good luck to me getting it all back together. Oil cooler is held on with triple square (12 point) bolts arrgg. My triple square socket is delayed in shipping, considering risking it with an allen wrench (that's how I got the one on the manifold bracket off).

Should I do anything with the fuel injectors? 2 came out with the fuel rail and the tips had a little stuff caked on, didn't know if it was ok to try and clean them. Or just let them be since they haven't given me problems. Already a little nervous not getting new teflon rings, but don't have the tool to install em. I did get new o-rings for the other end into the rail though.


Old and new part


Piece left inside rear of head


Blurry progress, oil cooler to go


Yummy (that's the worst one, most of the others look like the one on the right)

[The Infiltrator]

Just a little update... Turns out that the coolant flange on the back of the head was leaking. I'm hoping that it's the only leak (and hopefully that's why my heater core gurgles sometimes) I think it was actually cracked, so when I removed it part of it stayed in the head. (see pics) Hopefully that solves the disappearing coolant issue anyway. I've gotten just about everything off, good luck to me getting it all back together. Oil cooler is held on with triple square (12 point) bolts arrgg. My triple square socket is delayed in shipping, considering risking it with an allen wrench (that's how I got the one on the manifold bracket off).

Should I do anything with the fuel injectors? 2 came out with the fuel rail and the tips had a little stuff caked on, didn't know if it was ok to try and clean them. Or just let them be since they haven't given me problems. Already a little nervous not getting new teflon rings, but don't have the tool to install em. I did get new o-rings for the other end into the rail though.


Old and new part

I would clean the injectors off while they are out and clean the valves. It also looks like that part is melted a little, as you said it has a ton of build up but it just looks like it. Pretty nasty!

[Homer_J]

Yea planning on doing the valves, should i just clean the injector tips with a clean rag or dip them in injector cleaner or something? I don't wanna clog up the fine holes and make it worse. Also don't want to damage the teflon rings with solvent.

Edit: I also see there are places you can bring them to get them cleaned out... such as here: https://www.injector.com/injector_service.html 100 bucks for all 4, hmm.

[Homer_J]

Alright, just to sum up this thread...

Got it all done! Difficult to say if the oil cooler was causing the oil to transfer to the coolant. The gasket was old and brittle but removing it spilled oil all over the surfaces so I couldn't check for evidence. A failed gasket could definitely mix coolant and oil. Don't know if that caused mine, it's a possibility anyway, time will tell.



Blurry shot of where it attaches to


New water pump and intake manifold installed too. I'll open up the old manifold later when I get time and see if I can come up with an easier fix than swapping the entire manifold to others with the same problem.

What mine looks like:


What it should look like:


When it's popped out like mine, the arm doesn't engage with the flaps so nothing happens. If I click mine back into place, it'll move the flaps again. Possibly if you drilled a small hole through the center, and then inserted the proper size screw to hold it in, that could be a workaround to buying a new manifold. I did have a vacuum leak through the center of it though too. As I said, I'll look into it later.


Got the new coolant flange into the back of the engine. It didn't want to go in, the hole isn't very smooth to start with, and I had to scrape a lot of residue off to make it round again. It still didn't want to go in easily, so I drove it in with the mounting screws. It flexed the plastic a little, but it went in. Not sure if it has stopped leaking yet.

I cleaned off the valves a bit. I didn't have the patience or time left to get them all shiny, I got them decent though. I used BG induction cleaner on one of the cylinders, and it just seemed to goop everything up more and make it harder. I supposed if I had time to soak, clean, soak, clean etc it would have ended better. So I just stuck with scraping and vacuuming. These cheap brass tools off amazon were great for this, nice assortment of angles to get to everything. https://amzn.com/B01B1TBB10


Lastly the new manifold needs to be adapted through vcds. Does anyone know how to do this? I have zero vcds experience, some of the instructions I found online didn't work for me. I went to 01-engine -> basic settings -> ...Some instructions said to select a group at this point, I don't have that option. I just have a dropdown menu with about a dozen choices. One of them said something like "test guide flaps", I selected that but it said aborted due to safety. I tried it again with the engine running and it said 'running' but nothing ever happened. At first the car would only idle, but after fiddling with this the gas pedal worked again. (coincidence?)

I've gone to adv. measuring blocks and selected specified flap position and actual flap position. These don't typically match. (IIRC Specified was usually around 20% and actual was 0%) When I accelerated hard, they both would match at 99%. Does anyone know if this is normal?