M3 Ninja

07 Q7, 4.2L v8

My wife told me the coolant lamp came on, so I went to top it up with some water. I noticed the coolant was brown, and there seemed to be oil across the top. I got it flushed this morning, and the tech noted the oil, and flushed the tank 3 times to get it all out. I just checked the coolant again after getting home, and there was still some oil on the top. I got out what I could, to see if it was just residual from the flush.

My question is, is there any other possibility besides a head gasket? I've taken this car on long road trips, and there's never been an overheating issue. There is no coolant in the oil, and I don't seem to be losing oil from the dipstick.

The techs said that maybe someone put oil in there on accident, and one of the guys at the shop said that sometimes it happens, then never comes back.

Any help would be appreciated. If this persists, I'll probably get rid of the car. Head gaskets are a job that I do not want to deal with.

smith2010Q7

Before it is a head gasket, we need to check some things 1st.

On the 4.2 there is a Oil/water heat exchange in front of the engine if could be crack from inside of the cooler. (letting oil into the coolant line)

Also check on your radiator sometimes transmission oil lines goes into the radiator to be cool. It could also be crack inside the radiator. (cannot remember if the 4.2 have this I think it was replace by the exchanger).

M3 Ninja

My friends think it's the oil cooler, too. It's only a little bit of oil, its not milkshake action.

I did look up the trans cooler, and it's oil to air, no coolant involved.

M3 Ninja

Well, I had a bunch of beers, and decided I'll replace the oil cooler. We really like this car, and it seems silly to dump it over a part I can get on ebay for $80. I'll drain the coolant and keep it, since it is basically brand new. I'll just skim the oil out of it.

The procedure doesn't seem THAT bad on ELSAWIN. You have to drain the coolant, remove a coolant hose, the alternator, alternator bracket, and an air pipe. I believe I will remove the electric fan as well, to gain more room.

I'll try and make a DIY out of it.

smith2010Q7

Hope this will fix it, I would have done the cooler 1st also. Then flush the system again. Need to total removed the oil so it will not seep though the head gasket.

hoost

I've got a similar problem on my 07 Q7 4.2L. Oil in the coolant reservoir. Haven't had any issues with overheating at all. Had it into the dealer for diagnostics and they want $6700 for the replacement, so I'm thinking I'll be trying to tackle this on my own as well.

I've been browsing the repair manuals and it looks fairly straight forward...these might be the famous last words. Please post up your progress and let us know how it goes; I'm not sure how soon I'll dig into it, so I'll be interested to hear any tricks you discover.

M3 Ninja

Wow that is a steep bill. I thought the same thing, that it was pretty straightforward. I priced out all the parts and should be doing this within the next week or two. I do plan on taking the electric fan out for extra room, which is not in the official steps. I was going to replace the water pump as well, but it is crazy expensive with a built in thermostat. It'll have to wait.

M3 Ninja

So they did diagnostics and said it was the oil cooler for sure? Or they were just guessing. Would be helpful to know I'm going to do the right thing.

pchansen

Wow! Good for you! I look forward to following your progress.

hoost

They said it was most likely either the head gasket or the oil cooler, but since it hadn't over heated it was more likely to be the oil cooler.

Thinking about it now, I'm guessing their quote included tearing into the engine to get to the head gaskets, because when I questioned him on the pricing, he was telling me how many gaskets had to be replaced, etc.

I was busy with work, so I told him we'd wait and sent my wife to pick up the car. It wasn't until later when I cracked into the manual that I saw what was involved.

Also, Im going off memory, but I think the manual does recommend removing the fan shroud. It may be in the section on removing the generator (alternator).