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Coolant Temp Gauge

Posted by timbulb ( on
Mon, May 19, 08 at 8:17

I have an '02 Mazda B2300 truck. (Basically a Ford Ranger)

The coolant temperature gauge has started to work intermittently. It reads accurately but then just cuts out and reads nothing. Sometimes it'll flutter up and down. I'm assuming/hoping it's just a sensor. My question is, where is the sensor for coolant temperature? I've looked and can't seem to find it.

Follow-Up Postings:

RE: Coolant Temp Gauge

Its usually near the thermostat, but I don't know about the Mazda truck. Look around where the upper radiator hose connects to the engine,and/or the hot side heater hose.

RE: Coolant Temp Gauge

This may or not be helpful. But it can't hurt.
Check the coolant level in the radiator.
If the coolant level gets below the level of the sensor,
it can cause the guage to have oddball readings.
May not be the case here, but it can't hurt to check.

Check the coolant level in the radiator, not just the overflow tank.

Pooh Bear

RE: Coolant Temp Gauge

Funny thing is, my rad has no spot to fill it. It appears the only place to add fluid would be into the reservoir. The rad has no actual cap on it.

How would I ever fill a new one if I replaced it? weird.

RE: Coolant Temp Gauge

Some engines have a fill cap at the thermostat housing. this doesn't permit a complete fill, but may be enough to fill the engine head.

When there is no filler cap a the highest point in the coolanst system, the system is filled by removing the upper radiator hose and filling through the upended hose. You may have to crack open the cap at the thermostat housing (if present) to vent air. When system is full, close the caps, reattach the hose, and fill the overflow bottle to half full, then start the engine. After the engine warms, shut down and cool to suck fluid from the overf;ow bottle. It may require 3 thermal cycles before the system is completely filled. Refill the overflow bottle as needed.

If you find no filler cap, check the overflow bottle. It may have a pressure cap and seal with relief valve. There has to be a relief valve in the system somewhere to limit the pressure in the coolant system.

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