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Although it may look like whipped cream or mayonnaise, it's more than likely a mixture of coolant and engine oil.

Have you drained it yet?

 

Drained the coolant? No, not yet.

The only way I know of oil getting into coolant is a cracked block... or are you suggesting it got in there when they replaced the balancer?


The car has been running fine since I got it back, its been three weeks.

 

Also.. I JUST changed the oil and it looked fine. Black. But fine.

 

Whipped cream generally means oil and water. It's often found on the oil cap, but that's usually just water condensing on the top of the valve cover.
Check the dipstick, and it might be worth loosening the front bleed screw (just behind the radiator) and see if the coolant is running clear there.
Could be an anomaly, but definitely worth checking things out. Shouldn't have anything to do with replacing the balancer itself, but if it overheated too much you could have a head gasket issue.

 

The possibilities are endless. It wouldn't be the first time someone put something into the wrong hole.

A coolant change is one of the less expensive things we do for our cars, so if it hasn't been done recently, you might find it worthwhile. Also, take the opportunity to remove the coolant reservoir tank and clean it. For the present, I don't see anything alarming, yet it would get my attention.

Let's hope that others reading this thread will get the idea that checking things under the bonnet is a good thing to do.

 

I flushed it and refilled it. Lets see what happens. ...

 

Could be a cracked block, but more likely is a blown head gasket or potentially a warped head... Has the car seriously overheated anytime in the past?

 

My bet is on the individual who did the thermostat change. It may have been on a Monday, he could've been hung over and added oil to the expansion tank instead of coolant!

 

Any difference after a week?