High temp gauge drops when braking?

This one has me stumped.

I got a 1992 Ford Explorer 4.0 4x4 and automatic.

I replaced my intake manifold gasket (upper and lower) this weekend and when we got everything back together, the engine ran fine, no leaks, sounded good. But when we started it up the temp gauge was way over. Then we finished adding more coolant once the engine sucked more into it. Still high, but not all the way to the "H" on the gauge. So we took it out on the highway through the city and then onto the freeway and up a small hill on the interstate. Everything ran consistantly with the gauge right at the "O" in the "normal" on the gauge. I go back through town and when I put on the brakes and come to a complete stop, the gauge raises up nearly to the "H" and then proceeds to drop back down to midway on the gauge. It takes about 15 seconds for it to rise and then drop.

The coolant was good. I double checked for leaks. The top radiator hose was pressurized and hot. The radiator spit back a bit of the coolant into the overlow can.

Right now we're thinking it is probably a wire that got pulled to hard and might be grounded near a brake wire. Or it is possibly a faulty temp sending unit or maybe even a bad guage.

Any ideas? You guys really helped me out with my pinging. After changing the intake gaskets, cleaning the carbon off with some SeaFoam cleaner and cleaning the MAF sensor, no more ping.

Thanks in advance for the assistance.

Reply to
Romer
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You either have a bad thermostat or air in the system. Stat would be my first guess.

Dave

Reply to
Hairy

I ended up changing the coolant temp sending unit and putting on a new radiator cap and that fixed it. Now the temp gauge reads correctly and barely moves.

Reply to
Romer

Where is the coolant temp sending unit located??? My gauge hasn't worked in quite some time and I would like to change it. Thanks.

Reply to
Darby

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