Questions and Answers
Hot and Getting Hotter
Q. I have a 1991 Toyota P/U, 22RE, 209,000 miles, stripped down (no A/C, P/S, etc... the basics... fuel injected...). Three years ago the aluminum head became corroded and worn away from the antifreeze which necessitated a head job (welding and all the requisite labor). A year later, WHENEVER I TURNED ON THE HEAT, the temp gauge began rising rapidly. I replaced the thermostat, recored the radiator but to no avail. I have spoken with many experienced mechanics (save for the boys at Toyota) and I am met with shakes of the head... Can you help me?
A. Add one more to your list of head scratchers. This makes no sense to me at all. When you turn the heat on, a valve in the heater line opens and allows coolant to flow through the heater core. This takes heat away from the engine. If the heater core was plugged up or the valve stuck closed, that still would not explain the problem.
I'm thinking it might be an electrical problem. What you need to do is take off the radiator cap and stick a thermometer in the radiator. Turn your heater on and see if the coolant temperature actually rises. If it does, then my guess, and this is only a guess, that something in the head is wrong. If the temperature stays the same, then you have an electrical problem. You might be able to confirm this by putting the temp selector to full hot position but not turning on the fan. If it the temp stays steady turn the fan on and if it rises, then it's a good bet that something electrical is screwy.
Let me know what you find out, I'm very interested in knowing what is causing this problem.
