Quote:
Originally Posted by Jim/TX
Use the block test kit from NAPA first to see if it is a head gasket or cracked head or block. Blue fluid turns yellow very quickly if you have any combustion gasses at all in those bubbles. Easy test to do and definitive.
I have done the "disconnect fan belt" thing and still had bubbles.
I put some Hot Tub and Spa antifoam additive (just a small amount) in my radiator last year when running only water and anti-rust additive, and the foam ended right away. (The bubbles did not end, but the foam stopped.) I had the additive here in the shop for my hot tub at the house and I figured I would give it a shot. It is made for hot water, so what the heck...
I believe my bubbles are being formed by hot spots in the cooling jacket in the engine. Difficult to prove, but I ruled out combustion gases and air leaking at the water pump shaft. I was at a loss for any other explanation.
Unless the engine has been rebuilt recently and the cooling jackets were cleaned well, there is no telling what sort of rust, scale and crud has built up in there that will interfere with cooling. If steam bubbles form in the block, get stirred up by the water pump on their way out, and bubble up into the upper tank, you have foam.
Regardless if the foam is air or steam, the Spa foam breaker additive stopped them.
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Jim,
That's very interesting about your anti-foam agent--clever idea!
What bothers me is that you still had the bubbles. I'm surprised that steam bubbles would persist long enough to get to the radiator, unless the coolant was also at the boiling point, which I doubt was the case idling in the driveway.
I'm wondering if you might still have a combustion leak. Most of the times I've used mine it's taken several pumps on the suction bulb to get the color change. Also, it's important to have a good seal around the filler neck, so you're not drawing in fresh outside air.
Steve