another temp light problem

Sigeats · Posted: Mon Oct 10, 2011 2:15 pm Post subject: another temp light problem

Start engine and temp light blinks until my radiator fan kicks on, then it goes out. After that everything seams to work fine.

Thoughts?
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'84 Westfalia

Ahwahnee · Posted: Mon Oct 10, 2011 2:24 pm Post subject:

Have you verified that the pressure tank (this one)...

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...is full when the light is blinking?

How soon does your fan kick on (mine takes a long time idling or a steep mountain road to get to that point)?

Sigeats · Posted: Mon Oct 10, 2011 2:32 pm Post subject:

yes, pressure tank is full. Fan doesn't kick on until I let the Van idle in the driveway for about 30 minutes. The temp needle needs to climb to about the top end of the light before the fan kicks on. I have a new temp switch on the radiator, and my mechanic tested the switch with one of those temperature sensor gun things, and the fan kicked on exactly when it should.

I figure it must be a bad connection or something since the light stops blinking the second the fan kicks on. When the fan turns off again . . . usually about ten or twenty seconds after it initially kicks on, the light remains off as is should.
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'84 Westfalia

Sigeats · Posted: Mon Oct 10, 2011 4:08 pm Post subject:

on second thought . . . the switch is not new. Maybe I have a bad switch on the radiator. Is that hard to replace? Do you just unscrew it quickly and try to get the new one in before to much coolant escapes? I guess I could replace the temp sensor in the pressure tank while I'm at it.
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'84 Westfalia

Ahwahnee · Posted: Mon Oct 10, 2011 4:23 pm Post subject:

New or old -- sounds like your radiator switch is performing normally.

That sensor in the pressure tank is not a temp sensor, just checks that the coolant level is nearly full (simple completion of a circuit when the tip of the sensor is immersed).

You can get that sensor out of the circuit by unplugging the plug to it and jumping those connections -- a paper clip should do it. If doing that resolves the problem then likely that sensor is bad.

Could be that it is failing (they can get corroded/contaminated) and only functioning when the coolant is very hot.

Sigeats · Posted: Mon Oct 10, 2011 4:30 pm Post subject:

When I unplug the wire connected to the sensor in the pressure tank, with the engine running, the needle on the temp gauge shoots up as if the temperature was crazy hot . . . is that normal?
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'84 Westfalia

Sigeats · Posted: Mon Oct 10, 2011 4:34 pm Post subject:

. . . also, the light starts blinking again with the wire on the pressure tank unplugged . . . sounds like that part is working as it should.

Maybe just old corroded sensors like you said.
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'84 Westfalia

Ahwahnee · Posted: Mon Oct 10, 2011 5:04 pm Post subject:

Normal... now jumper the plug to see if that settles the needle & gauge down.

Sigeats · Posted: Mon Oct 10, 2011 5:06 pm Post subject:

Will do . . . thanks for all your help!

I'll post the verdict when I get a chance to test it.
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'84 Westfalia


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