I just reinstalled my engine and pressure washed it (not first time) and now my Temp guage goes straight up to H when I turn the car on... I searched but nothing really answered my question. Any help would be greatly appreciated..! thanks

 

Next time dont power wash.

Anyways, try checking your coolant temp plugs/wires. Sounds like they either have become damaged, or have a break in the wire.


Modified by my_slow_civic at 11:17 PM 12/1/2005

 

there's only one wire for the cluster, and it's a thermistor. If it is unplugged, you will show no reading. If you hook the wire straight to ground, it will sky rocket to HOT.

I'm sure your temp sender is bad. It's the small sensor on the pass side of the head, under the dizzy. I believe it's a 12mm holding it in. Test like this...

remove the wire from the sensor
short it to ground with the ignition OFF
go inside the car and turn ignition on. The temp gauge will start moving to HOT very fast IF the gauge cluster is good.
Turn ignition OFF when it starts moving, or you may damage your cluster.
Unplug sensor and turn ignition ON. If the gauge moves, you have short to ground somewhere. If it only moves when shorting the sending wire, then the thermistor in the sender unit is bad- replace.

Sorry, best I could do while hurrying to type

 

If you re-installed the engine wouldn't you have to drain and fill the coolant?

If so its possible you have an air bubble in there causing your problem.

If not sounds like a bad sending unit,