Hey all, pretty new owner here. I recently developed an issue causing my '96 lt4 to overheat within a few minutes after starting the car. I have a strong feeling this is due to my Water Pump biting the dust, but I wanted to post here to see if anyone knew of some other things that might cause this before going down that rabbit hole.

My first thought was low coolant (or an air pocket caused by low coolant) disrupting my system. I flushed the radiator and put in new coolant (I know for a full flush you're supposed to take out the knock sensors too, but the fluid drained from the radiator looked pretty good). I've been trying to work out any air from the system, but so far it hasn't really helped the issue.

Once the system is hot, I noticed a couple things regarding the hose coming from the pump to the radiator and from the radiator back to the pump. From.the radiator to the pump, the hose is far far cooler than, say, from the surge tank to the water pump. The the point where the hose from the radiator to the water pump is cool to the touch, while the hose from the surge tank to the water pump is far too hot to touch. Secondly, the hose from the water pump to the radiator is scalding near the pump, but cool to the touch near the radiator, which seems ridiculous over such a small run.

Anyone have any ideas that might cause this? Anything I should check before I start planning for a water pump (and probably optispark with it) replacement?

 

The thermostat might be stuck? If you have one hose hot, while another cool, it means that there is a circulation but the wider loop is not open. It's cheap and should be easy to change

 

@skukunin You're the GOAT. It ended up being the thermostat. A quick run to advance auto parts near me, $18, and half an hour and my car is running perfectly again. Thanks for the help on this one.

 

A bit late now, but there's two styles of thermostat, one fails while closed and the other fails while open. Might be tricky to know the second fails until the winter hits, but it's better than suddenly overheating in the middle of nowhere.