I recently had some work done to my car, about 5k miles ago, and all of a sudden today I had an issue with it overheating. I have a mezier water pump w/160 stat and aftermarket radiator. It didnt seem like it was overheating until I was at my destination when it said overtemp. I turn the ignitin key to on, not started, and let it sit and the temp will drop pretty rapidly. However, when I drive it quickly climbs to the red. Any ideas? It sounds like the stat, but I've never had an electric water pump before either. It was bought new with the stat at time of install. I assume the water pump is good since the temp recovers when ignition turned to on, not started, and the coolant drops. Any advice would be appreciated.

 

I think the first thing I would do is look for the obvious. Get under the car and look at the plenum area in front of the radiator for debris that might have been sucked up off the ground. Vettes are bottom feeders as I am sure you know so have a visual. I would check coolant levels and try burping the system for an air lock. Seems unlikely that would be the case with the temps going down with the electic pump on but it is worth a check. I have no experience with an electric water pump but you can check the thermostat in a pot of water and see where it opens. Give those things a look and report back. Good luck.

 

Ok, here's alittle bit of an update. The radior is clear, and i was feeling the coolant temps of the hoses and the one on the lower end of the water pump, I assume that is where the stat is, is cooler than the top one going to the water pump. I've never replaced a stat before but i assume it's a pretty easy job...right?

 

there is a write up here on changing the stat. you have to be quick with your hands but you can do it with very minimal coolant loss.

 

Check post 9 http://forums.corvetteforum.com/c5-t...nning-hot.html

and check your thermo it may be stuck. throw it in a pot of water..

 

Ok, with it being an electric pump, it's alittle harder to replace the stat as it is located somewhere else. I dont have the tools to remove the spout and to check/replace it...that and it is an SBC stat that I need to try and find.

 

If the temperature drops rapidly with the pump running and the engine off it would seem to me the thermostat is opening. The other hint is the difference in hose temps; if the engine is hot and there's flow through the thermostat (and therefore the radiator) the top hose on the left side should be so hot you can't hold your hand on it, and the lower hose on the right side should be much cooler since any coolant flowing through this hose will have cooled in the rad.

It sounds to me like maybe the pump is working but not flowing enough coolant to cool the engine? I have zero experience with electric water pumps but as a sanity check I would inspect all of the electrical connections to the pump and make sure it's getting a full 12V or more while running. Maybe a bad/weak electrical connection?

Maybe the thermostat is opening but not fully or at the proper temp? As others have suggested, you can put the stat in a pot of water with a meat thermometer and check that it opens at the correct temperature, and opens FULLY by the time the temp has risen a bit more. I've only checked an OEM thermostat, but I would imagine a 160 should be fully open by 180 degrees or less. My OEM stat looked fully open by about 210, and I think the temp rating is 195.

If you find your issue please update us - it will be interesting to hear the cause.

 

Ok, I found the issue. I thought I had been hearing the pump running while the key was in the on position. Well, while I had checked all the fuses the one thing I couldnt check was the relay to turn on the water pump. Well it turns out the relay had crapped out on me. I guess I need to carry a few of those in the car for long road trips...just in case. Quick and cheap fix.