hello. My sister has a 91 accord. This morning, she comes running to me telling me that her temperature gause is through the roof. I take a look at the car and the temperature rises to the red zone in less than a minute of idleing. There is plenty of antifreeze. There are no leakes. I checked cooling fan relay and fuse and that is functional. I dont want to throw money into it unless I know what the problem is. I am thinking thermostat but it seems to overheat very quick. I also suspect the water pump might have broken at the shaft, but unlikely seeing that there are no noises or leaks. Please give me some advice, thanks in advance.

justin

 

Radiator full?
If you only checked the reservoir bottle, you don't really know if the actual radiator is full.

Does the fan run when it overheats?
Normally you could jumper the fan switch with a paperclip to verify the fan can run. But I think '91 has the fan timer & 2 fan switches, so maybe someone can help you out about which fan switch you should jumper.

Does it overheat while driving?
OK, don't run out & try this until you're sure the radiator is full. Driving along at 40mph pushes more air thru the radiator than the fan. And besides, the engine makes way more heat driving vs. idling. So if it doesn't overheat while driving, you know your waterpump & T-stat are OK.

After it's cooled down, you can open the radiator cap. Run the engine until it heats up, then you should see motion in the coolant. If the waterpump is gone (broken shaft) the coolant will never move.

Check the electrical connection to the temperature-gauge sender. It'll be a 1-wire sensor in the end of the head. I'm pretty sure (even for '91) all the other sensors are 2-wire. If that wire shorts to ground, the gauge will suddenly read full-hot.

 

the fan switch to jump is the one on t-stat housing left of distributor
if you start car when it is totally cold and gauge jumps withing seconds it is an electrical problem,, bad sending unit, bad gauge,, if it jumps to high after a bit of running could be t-stat, grab the lower radiator hose and it should feel hot to the touch if it feels cold, or cool you got a t-stat stuck closed ..turn a/c on both fans should come on that way you know that your fan motors are ok if either does not work chk fuses for fan motor first ,,,