coolant light flashing at startup

[corwine123]

Alright so a little back ground info. I bought an 84 quantum TD last month from the original owner, it has 143,000 miles. Has had a few probs so far but nothing serious, popped speedo cable, and leaking rear proportioning valve ( still havent fixed that one). But overall it is a great car and i love it.

The past few days right when i start it up the coolant light starts blinking and the temp goes all the way to the max. So I turned it off checked the coolant level, it was good and was not hot, neither was the engine, so i drove on. About 2 or 3 minutes later when the engine would normally be getting to normal operating temp the temp needle drops close to the bottom and starts to rise as usual to normal operating temp and there is no flashing coolant light. I haven't noticed any loss of power or increase in smoke. What could the problem be?

thanks for any help

[corwine123]

could it possibly be related to the glow plugs coming on. It only seems to happen after the glow plug light comes on.

[Rabbit on Roids]

only time ive ever seen my gauge max out is if the sender wire popped off and was grounding out.

[Vincent Waldon]

Yup, the temp gauge and the overheat warning circuit share a common coolant temperature sensor, so the fact that both of them misbehave at the same time points to an issue with the sender or the wiring to it.

The glow plug system has its own sensor, wiring, etc... so probably not related.   It is possible that the temp gauge coolant sensor is only misbehaving when the engine is cold... which is also when the glow plug light comes on.