Thermostat stuck open?

[Nickel_Nackel]

Hello all,

So I've been driving my van to and from work a couple times a week. About 15 miles back roads going no more then 45mph then on the way back I take the highway going about 55mph.

I notice my temp gauge never goes out of the white. It bounces around in that zone when I sit idle and when I drive. (So the sensor is working properly.. I think)

I could be wrong and I probably am but I'm thinking the coolant doesn't sit around the engine long enough to heat up.

It does eventually get up to temp (sensor in the middle ish of gauge) after like 30 mins of laying on the rpms. Then the fan does kick on.

Is there a proper why to test my theory about the thermostat being stuck open? Without pulling it out.

I cracked the rad bolt and started up my cold van and two seconds after it's been running The coolant poors out the rad bolt. Does that mean the coolant is passing over the thermostat before it's warmed in the engine? Or is that always pressurized even when the van is cold?


I know it's cold here right now but it should not effect the van to getting to a proper running temp after I've been driving it for 45mins, right?

I'm going to re read the Bentley once I get home from work. But I'm hoping you guys could give me some ideas of what the issue could be.

Thank you guys,
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1985 1.9L Potato

[dobryan]

Based on what you wrote it sounds like the fan comes on when the gauge pointer gets to the LED? If so it seems like it could be a gauge calibration issue. The normal operating temp is at the LED (50%) or so. At somewhere about 75% or more the fan comes on, if temps get hotter the higher speed fan kicks on. All in my experience, YMMV.

I would take an IR gun and check the temps of the engine at various points and at the coolant hoses near the thermostat. You may have a stuck thermostat or a it could be misleading gauge read out.
_________________
Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD

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[Gauche1968]

Ground the sensor for the gauge and see if it goes all the way to the top of the indicator.
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1984 Vanagon GL
1984 Vanagon Westy

[dhaavers]

Compromised connection at the gauge sender will give you low reading.
Clean corrosion, replace connector if wire is worn, stripped, broken, etc...

- Dave
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86 White Wolfsburg Westy Weekender
"The WonderVan"
<EDITED TO PROTECT INNOCENT PIXELS>

[Nickel_Nackel]

[dobryan]

[Wildthings]

The quick and dirty test is to just note how quickly the heaters warm up and how hot they get. If everything seems kosher there then you may have a gauge issue.

I think you can get an IR thermometer from Lowes these days for about $25. I bought one 6'ish years ago and it is still working just fine. Not sure why your fan would be coming on at this time of year, with the stock thermostat and stock fan switch the fan doesn't kick on often enough in the summer IMO and almost never in the winter. As others noted the fan operation is fairly independent of the thermostat. It might be tied in with a partially clogged radiator though.

I am guessing that you have both a bad thermostat and a bad radiator, this really isn't that uncommon. Radiators slowly clog with time and even new thermostats can fail.