Tuesday, November 6, 2007


What's this greyish-brown stuff coming out of the cooling system? This kind of Yuk! happens when water and oil mix.

Usually when you see an emulsion like this in the engine. Which then means either the water pump seals are bad and/or the head gasket is blown, and water got into the engine.

Here, it came out of the cooling system. There was a ton of oil in the system. It was like mud paste. Never seen anything like it. Seemed like more oil than water.

So we took the water pump apart, did a leak down on the engine to determine if the head gasket was blown, and that checked out all ok, and then realized that the oil cooler had internally fried o-rings, let the oil leak into the cooling system, and needed a rebuild.

That probably happened when the thermostat got stuck, and there was no cooling the oil and the oil cooler, and the o-rings burned. Or, the o-rings burned, let the water and the oil mix, and then the emulsion made the thermostat stick, but the first scenario is a lot more likely. Or the bike is just really old and the o-rings reached the end of their life.

So if your radiator stays cool, and the temperature is up, check your thermostat. Needless to say, this is not too good for the engine. In this case the engine seems to be fine, and although it is a lot of work to rebuild, and clean the cooling system, it'll be ok in the end. Phew!

And I am really glad that we wear gloves here at the shop. Wouldn't want that slimy mess on my girly skin...