Oil in surge tank

[Meathead16]

What might cause oil to get in the coolant surge tank? It's not a lot, but there is definitely a dark "residue" in there in some spots. The air box also has some wetspots on it and it the overflow hose and outside of the tank is wet as well. Coolant level slowly but steadily drops. Once below the mid-seam of the tank it seems to level off.. or at least expel the coolant much more slowly. My guess is headgasket and the combustion pressure is pushing coolant out of the tank? Have been having a slight misfire at idle, but I was attributing that to the exhaust leak I have (bolt head closest to cyl 1 disappeared on me... strangely enough, the soot marks are at cyl 5 and 7, its clean as can be around the sheered bolt) causing a rich condition (~15%+ long term). Exhaust does have a slightly sweet aroma to it. I was first alerted to it when I noticed white smoke coming from the exhaust. Giving it throttle really increased the smoke. After a few minutes of driving it stopped smoking though, it seemed too solid to be what you see when it's cold out. It did it pretty bad once or twice, and it had done is slightly a couple times before but it was actually cool and rainy those days so I thought it might have been that but even when it was cold temps were over 50. What's strange is it hasn't happened since then. No codes, no milkshake residue... I do kind of get on her once in a while... well.. pretty regularly, not flooring it, but I am a spirited driver.. usually keep the rpms below 2500 though.. How common is it for the radiator to fail where the oil cooler is? The oil cooler is in the left radiator side tank right? Besides that and the headgasket, is there really anything else to explain what's going on with the surge tank?

 

[OR VietVet]

IMO, you are on the right track. I am old school and at this point, I would remove all plugs and inspect and do a compression test.

 

[Joseph Garcia]

I cannot personally assist you with your issue, but other members of this Forum much more knowledgeable than me in this area will chime in.

Are you sure that it is oil in your coolant surge tank? There was a thread here within the past year of discoloration and sludge on the coolant surge tank, and it turned out to be decomposing coolant.

 

[mattbta]

You mentioned no milkshake - did you pull your valve covers and inspect? Also, does the oil fill cap have any moisture in it?

 

[Meathead16]

IMO, you are on the right track. I am old school and at this point, I would remove all plugs and inspect and do a compression test.

I'll go to my flaps today for a loaner tool

I cannot personally assist you with your issue, but other members of this Forum much more knowledgeable than me in this area will chime in.

Are you sure that it is oil in your coolant surge tank? There was a thread here within the past year of discoloration and sludge on the coolant surge tank, and it turned out to be decomposing coolant.

I replaced the water pump about a year ago and refilled with fresh coolant. Is there anything that could cause it to degrade that quickly? I'm not sure if it's oil or not though. A lot of it was external from dirt and dust collecting where it was wet from coolant coming out of the overflow, and what's internal looks very similar. Maybe somehow dirt is getting in the tank under certain conditions and the two issues are unrelated?

You mentioned no milkshake - did you pull your valve covers and inspect? Also, does the oil fill cap have any moisture in it?

I haven't pulled the valve covers yet. I don't recall any moisture on the cap, but will check.