Got my S4 back from the shop today; during oil change and coolant flush, mechanics noted what they said were "very slight" milky signs in the oil pan and/or oil in the coolant. The owner told me this would generally indicate an initial failure of the head gasket, but it is so small that he thinks the car can be run without problems until the next oil change, where it can be checked again more thoroughly and dealt with as needed. He said the head gasket is unlikely to suddenly blow even with this small failure already starting.

Thoughts?

 

That doesn't sound good at all. I would not run my engine if there were any traces of coolant found in the crankcase. It's not a good lubricant. There aren't many ways that water & oil can mix. Next to an internal leak, the most likely cause would be a faulty oil cooler IMO.

 

There's a possibility that since the radiator contains both oil and ATF (if auto), the contamination may have occurred due to an internal core failure. The best way to confirm the head gaskets have failed is through compression testing. I hope it's not the latter. Good luck and keep us updated.

 

Run the car for a few weeks and get an oil or water sample and send it off to have it tested. There are also test you can do on the coolant to see if there is any exhaust gasses in there, which would be an indicator for a failing head gasket. (not done either but know of others who have done so) In the past two years, I've had to do head gasket jobs on cars that were sub 50k miles due to them just sitting there and rotting. The owners were lucky and observant because they noticed a slight puff of smoke and a sweet smell from the exhaust. Both were failing around the number 8 cylinder. No idea why it was there on both but it is what it is.

 

The CO test of the cooling liquid can be done at any VW dealership, as well as most garages I guess. They will probably do it for free (got some experience here)

 

I'm curious to know what is the mileage on your car..

 

I'd check compression or do a leakdown. Easy stuff.

 

Not changing the coolant often enough is probably much more likely the culprit than mileage on the engine.

 

That's one thing that eats at me. I have changed my coolant every 2-5 years (coolant used says it's good for 5 years or 100,000 miles), but my block plugs are frozen. I can only get the coolant out of the radiator. I will maintain the 2-year interval of changing, but fear my head gaskets will degrade since I can't get to the coolant in the block.

 

Soak the plugs in penetrating oil everyday for a couple weeks leading up to the next change and flush. If they don't walk out then, there is no shame in using the hot wrench. An impact is also helpful. Don't give it too much hell with hand tools or you will snap the head off the bolt.

 

I'm not sure what's meant with "and/or"... Oil in the coolant wouldn't be good. But, a little milk in the oil might just be condensation from not driving it. I'm with Sean - put some (long) miles on it and keep an eye on your dipstick for milk and oil floating in the top of the coolant overflow tank.

Blackstone Labs can test oil; but I didn't see rad fluid on their website. (http://www.blackstone-labs.com/) For $25, I was VERY happy with them.

 

By impact, I don't mean the meanest 1/2" drive Ingersol Rand makes. An 18V cordless 3/8" drive would be ideal.

 

Sean--

There's a reasonable chance the cross contamination is from a damaged oil cooler in the radiator. Engine running, oil presure is higher than coolant pressure so a leak passes oil into coolant. Shut down a hot engine, and coolant pressure is higher than oil pressure coolant migrates into the oil cooler. You can pressure check the oil cooler in place in the radiator, or disassemble it from the radiator and bubble test it with air in a pan of water. I'd rule this out before going off towards the heads and block in panic mode.

Even a tiny bit of water in the oil system is a problem, so don't ignore the signs.

Curious what coolant was in the car and what did you put in it this time?

 

I have one of these and it works pretty well: Lisle 75500 Combustion Leak Detector


A lot less time and work than doing a compression test. Hopefully your problem is just condensation.

 

Coolant in your oil will thin it out and cause rod or main bearing failure. I think its your oil cooler in the radiator that is bad. I would take the radiator out and have it pressure tested.