My normal commute is pretty short (about 6 miles) so maybe it doesnt have a chance to get very hot. last night i drove my truck longer than normal and when i parked, i noticed steam was coming out of the heater control valve. When i bought the truck, the valve wasnt bolted to the fire wall. I drove it home that way about 30 miles without losing any coolant. I recently replaced the bolts that hold it to the fire wall and havnt had a problem until late night. This morning i drove it to work and didnt see or smell any coolant. Where do leaks typically occur in this area? I read that they revised the valve for the 88 trucks, can i use this one? Any modifications required? Ill only replace it if thats the part thats leaking

 

If your truck has the stock brass heater control valve, its common for them to freeze up or corrode and leak. Replace it with a heater control valve from an 89 or later truck or 4Runner, either one will work. I replaced the heater control valve on my 86 4Runner with one from an 89 4Runner, its a direct replacement.