Questions and Answers

Toyota SR5 Blown Head Gasket Q. Dear Mr Ciulla, My 1987 Toyota 4WD pickup seems to be losing coolant and an abnormal amount of white smoke is exhausted from the tail pipe when the engine is cold. I have not noticed any abnormalities in the engine oil or color changes in the coolant. I have noticed that there is bubbling going on in the coolant reservoir once the engine heats up to normal operating temperature.

I surmise that this is caused by a defective head gasket, but if this is the case, why isn't there any noticeable discoloration in the coolant? I was going to do a compression check, but the Toyota manual suggests that the cold start fuel injection wire and the solenoid resistor be disconnected prior to doing the check.

The manual doesn't show where these are located; could you help me out on how to locate these connections, and comment on the bubbling going on in the coolant reservoir? Also, once the engine heats up to operating temperature, the exhaust becomes normal (no steam). Additionally, the engine seems to be running normally, that is, acceleration, highway driving and idle seem to be normal.

• 1987 Toyota SR5 4WD
• 160,000 miles
• Manual transmission

I have read through 70 pages of your Q&A section but found nothing in this regard. I would appreciate any help you can give me on any or all the above questions.

Thanks,
Bob

A. You surmise correctly. Your head gasket is about to blow. It's at an early stage where when the engines is cold the gasket is drawing in coolant and producing the white smoke. As the head gets hot, it expands and seals the head gasket again. Quite often, at this stage, a cylinder head re-torque it will extend the life of the head gasket.

A blown head gasket will not change the color of either the oil or the coolant. The bubbling in the coolant reservoir tank is actually combustion gases pushing out through the head gasket and into the cooling system.

In fact this is used as a test. There is a special tester with a dye that fits over the radiator neck. The dye changes color if there are combustion fumes in the cooling system which indicates a bad head gasket.

By looking at the spark plugs you will be able to see which cylinders are burning coolant. The porcelain around the spark plug tip will be white as snow.