Picked up a car recently that had been sitting for a couple months. Coolant tank was empty, battery was dead and oil looked dirty. Got it home, charged it, drained the oil and the first thing that came out was coolant, followed by oil. Neither were mixed, it looked as it would if you poured oil and coolant into a container and left them to separate. Wasn’t the typical milky look. Put in new oil, had to add maybe a quart of coolant, and it started right up. Let it get up to temp, nothing out of the ordinary, didn’t warm up quickly, not misfiring, compression was 160-170 across the board. Coolant color is normal, Ill be draining the oil again tonight to see if it mixed again but any ideas on the culprit? I am doubting a head gasket issue considering good compression, no misfires, not overheating etc. Anyone familiar with the oil cooler, there isn’t a gasket in it that could fail and allow them to mix is there? I think the cooler it self would have to fail completely.
Possibly a previous owner that didn’t know what they were doing?
My neighbours wife once poured windshield washer fluid into the engine of her Mazda protege. As unbelievable as that sounds it’s a true story.
S4 or RS4?
Oil cooler is a likely culprit.
Thats what Im thinking. Oil looked, well like oil again when I just drained it. Ill probably do a leak down and further pressure test the coolant system but think its just the cooler at this point.
I thought that too but I don’t think so.
I saw this on a guys car i worked on where somehow the oil cooler got damaged. The only real chances would be head gasket or if someone poured coolant into the oil cap. If you can take some pictures and see if you can document what failed. Are you getting back into the S4s again or did you just find a good deal.
Sorry forgot to say its an rs4. The oil cooler doesn’t have a gasket to fail and allow mixing does it(think b5’s are this way)? The cooler itself would have to fail.
Another RS4 man your really doing it big. I would then say yes more clear cut sounds like they mixed
Its wrecked (rear), just want the motor. PO gave me all the service records, didn’t have any previous problems, coolant system was actually checked about 7K miles ago but it has been sitting at copart for a few months. Ill do a leakdown this weekend hopefully.
If you are swapping the engine into your other car then I would change out the rear coolant pipe seals too.
This is for the same rs4 you have been trying to put together I take it.
That’s the plan right now
Good idea.
So cold leakdown came back perfect. I’m going to try to seal off and pressurize the coolant lines and oil cooler separately, could still be a break between a coolant/oil passage but wouldn’t that be pretty unlikely?. I found the hose off the passenger top side of the radiator may have had a nipple cracked, could have been why it was low on coolant when I picked it up and maybe some dummy put it in the wrong place.
Good for you.
You can pressure the coolant system and open up the oil lines. Don’t put in oil. If you pressure the coolant side and put water in you should be able to see weeping if there is any issues.
Pressurized the system with just air, it slowly drops in pressure from 20 psi. If I listen to the ports in the valve covers I think I can here it. Its not the oil cooler, I deleted that for the test and it is still doing it. Sounds like I need to replace the head gasket.
Sounds like that can be it. Pull the valve covers and pull the plugs try again. That should help get you more of an idea.
Yea I could hear it on the passenger side, not so much the drivers side. I have new gaskets coming in tomorrow hopefully. I bought both and might just bite the bullet and replace both sides.
Are you going to replace the head bolts?
yea I have vcg, head gasket, timing gasket and headbolts, rear coolant oring and the oil cooler o rings as well.
yes do this. audi did this under warranty for me back 80k miles ago.
I didn’t think you would neglect anything, but you never know.
I just remeber installing my heads on the S4 and going through the torquing sequence. Turning the head bolts another 90degrees after 120 ftlbs(I think) was pretty intense. All I could think of was one snapping and I know they are wretch bolts but it still made me nervous.
Good for you. That’s everything your going to need. Heck mabe even take some pictures and post em.