Engine temp problem

RANDYLB

MEMBER
1991 FORD E-SERIES VAN
134,000 MILES

My 1991 Ford E150 van was running cold {temp gauge would not go above the "N" in normal} Also could not get any heat from the heater. Took to mechanic, he said thermostat was stuck open. Had mechanic replace thermostat. Van heater now works great but the engine gauge continuously fluctuates between mid range and hot Mechanic now tells me it's an electrical problem. Need advice before I put too much money into this van. Help!

Friday, April 19th, 2013 AT 6:10 PM

1 Reply

CARADIODOC

MECHANIC
34,330 POSTS

Very often there is a small bleed hole in the thermostat to allow warming coolant to get over to it. The sensor for the gauge is a ways away from the thermostat. By the time the heat migrates over to the thermostat the gauge is already showing the temperature is too high, then when the thermostat finally opens, cool coolant rushes in from the radiator, the gauge goes back down, and the thermostat closes again. Eventually it stabilizes but it can cycle like that for 15 - 20 minutes. If that bleed hole doesn't exist in the new thermostat you can drill a 1/16" hole through the middle of it.

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Friday, April 19th, 2013 AT 6:25 PM