Coolant boils over without red light coming on and with gauge staying 3/4 up


koebes

New member
1986 water cooled Vanagon. Temperature gauge on long drives usually 2/3 up, when climbing steep mountains 3/4 up. Had it checked out last year. Everything's fine. Now driving for 4 hours from San Francisco to Fresno and then up to Sequioa NP: at 2,000 ft we stopped for gas. I turned off the engine and a short time later coolant was gushing from the rear; it was bubbling and boiling. Probably lost one or 2 quarts. Filled it up. Drove on to 3000 ft, stopped, and while the engine was running checked the coolant. Within a few seconds, with the engine still running, it was boiling over, etc. The red warning light did not come on and the gauge stayed 3/4 up.
So the car overheats and has to be checked, but what's with the gauge and the warning light. The light came on after driving just a little bit with low level of coolant fluid and went off after it was replaced
 

fbloch

New member
I had a similar problem and eventually figured out that my coolant presssure tank cap was defective (the blue cap on the tank closest to engine with the hose to the overflow resevoir behind licence plate). It was not holding pressure and so the coolant blew past the cap when hot and into the overflow resevoir eventually overfilling the resevoir and onto the ground. Don't know if that is your problem but it is a cheap and easy fix if that is your problem.
 

koebes

New member
I had a similar problem and eventually figured out that my coolant presssure tank cap was defective (the blue cap on the tank closest to engine with the hose to the overflow resevoir behind licence plate). It was not holding pressure and so the coolant blew past the cap when hot and into the overflow resevoir eventually overfilling the resevoir and onto the ground. Don't know if that is your problem but it is a cheap and easy fix if that is your problem.

Thanks!
That's exactly what the mechanic suggested after testing the cooling system. New Pressure tank cap ordered!
 

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