97V6Coupe

Hello:
While under the hood doing a routine check, I noticed the coolant reservoir had the top several inches an ugly brown color, Usually it's obviously bright green. I sucked the fluid from the top portion of the reservoir and there is definitely oil in the coolant, since it's very brown and oily feeling. I took the radiator cap off and there is oily brown fluid there too. This problem must have just started since the oil level and color looks very normal. I would think that the color would be more red if it was from the transmission fluid, but I have not checked the level there yet. If there any other likely cause other than a head gasket problem? The car seems to run, drive and shift normally, no overheating has been observed. Is there an oil cooler on this car that could be causing this problem? I can't even find a listing for an oil cooler on the normal parts listings that I use, the reason I am asking about that is that it is listed as a possible cause for some cars. Thanks.

97V6Coupe

I've done a little more investigation. Bought a "BT500 Block tester" device if anyone is familiar with that. it's supposed to check the radiator to see if there are combustion gases getting into the coolant. I ran this test a few times with the engine heated up and never got an indication that was positive for combustion gases. I then checked the device by placing it into the exhaust outlet and got an immediate change in color of the fluid from blue to yellow indicating combustion gas. So the device seems to work as advertised, but there is no indication of a head gasket leak yet. I'll try again over the weekend to run this test, but maybe the head gasket leaked for a short time and then sealed back up? The car was stored in an unheated garage over the winter month and was fine before that when I put it away last December. Or might it be that nefarious oil cooler which I cannot find a listing for anywhere? I guess I could take the oil cooler off (above the oil filter), but I don't know what to look for and the only thing I can find is a gasket which fits between the block and the oil cooler housing. I just can't see how that could be the problem. If anyone has experience with the oil cooler thing, please let me know.

Thanks in advance.

knightfire

Had the exact same thing happen.
It would steam out the exhaust pretty good in cold weather.
That lasted a couple years then once it sat over winter and a cylinder filled up with coolant. Brought it out of storage that year and tried to start it, but it hydro locked.
Took the plug out, cranked it, and coolant was blown out of that cylinder....
Bad head gasket confirmed.