Went to check out a Euro-spec 280CE automatic today with 150k miles. The car's idle is mildly lumpy (the engine rocks back and forth), and rests at around 550 rpm.

Prior to getting there, the owner told me the water pump sprung a leak. Upon starting the car up, it started spewing coolant out of the waterpump onto the ground. The coolant was coming out grey and milkish, so I assumed the headgasket was going. However, when I checked the oil on the dipstick, it was perfect with no coolant traces whatsoever. The seller stated that he added some sort of a stop-leak (sounded like Bar or Bark's) and it was causing the milkyness.

Popping the cap off the radiator, the coolant, when filled to the top, had a bit of an oily slick on it. When the car was being driven around (and I was behind the car for quite a while, driving in LA traffic to several smog shops before they could accomodate us), there was no white smoke, except for a small puff on one occasion which lasted for maybe a second on take-off. Although the car sat in traffic, there was no overheating.

The car ended up passing the CA smog check, although the tech mentioned that the idle was way too low. So, could this be the headgasket causing the low idle due to loss of compression and discoloring the coolant? Could coolant and oil mix in the radiator but not end up in the oil pan?

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- 2013 VW GTI
- 2004 Volvo S60R
- 1988 BMW M3