Overheating...How do you check a water pump?

[myersjeremy]

Well really haven't posted my latest problems on here so here goes. I finally got all my wiring and everything cleaned up and took the '85 out for a spin. The temp gauge pegged out so I immediately turned the engine off. It was smelling really hot!!!! I let everything cool down and checked the fluid levels and the antifreeze was good. Decided to take out the thermostat run it without it. For some reason I decided to check the oil and it was waaaaaayyyyy over full. Head Gasket......... Didnt look too bad so I tried the sealant in a can. Ran engine flush through the engine oil while idling with the head gasket repair in the coolant. Everything looked good once I drained the coolant and oil and refilled. Seems to have cured the head gasket. Now I went on another drive and overheated again. Caught it before it got way hot. I have flushed all coolant system over and over....took the radiator out and flushed every way possible. And now my question after all this......How can I check the water pump? It is still heating after flushing and flushing.....oil is still looking good though. Any ideas? I am about ready to stick a match to it and call it quits........Thanks for any advice!!!!!!!!!

Jeremy
'85 silverado 4X4
350

[bcolli3]

How much RTV did you use? I've seen that become dislodged and f all kinds of things up. good luck

[79GMC_OLDS]

Is your temperature sensor the correct one for the gauge?

[beaterC10]

You should be able to check the pump by getting the truck to operating temperature with the rad cap off. You should see a steady stream of coolant returning to the rad with the thermostat open. You should also have good heat from the heater assuming everything else is working. Lack of return flow or no heat at idle would suggest you have a bad water pump.

My experience has been that a bad water pump is most noticeable at low speeds and idle.

[Eyegore]

For the water pump, can you wiggle the fan blades, that is usaully a sign that it is bad, or coolant dripping out from the weep hole on the bottom of the pump itself.
Does it overheat when ideling for a period of time or only when driving it? I had this problem and the radiator was 30% restricted, put in a new rad, no more over heating.

Hope you find the problem soon.

[myersjeremy]

Messing around with the truck again tonight and it seems that the top radiator hose just isnt building much pressure and is relatively cool compared to the bottom hose when the truck begins to overheat. I am seriously thinking of slapping a water pump on and getting the radiator rodded but what if its a blockage in the engine block? How would I ever be able to tell that?

[myersjeremy]

And yes it is normally at idle when it begins to overheat.

[79GMC_OLDS]

Originally Posted by myersjeremy

Messing around with the truck again tonight and it seems that the top radiator hose just isnt building much pressure and is relatively cool compared to the bottom hose when the truck begins to overheat. I am seriously thinking of slapping a water pump on and getting the radiator rodded but what if its a blockage in the engine block? How would I ever be able to tell that?

well if you put your t-stat back in this would just mean your t-stat isnt opening which means it isnt getting warm enough to open it. I had a similar problem when i first started up my engine and i had a new temp sensor and it was reading way too high and i thought the engine was getting hot. I then used the old temp sensor from the diesel and the readings were correct. Are you sure the engine is overheating and its not just the gauge?

[piecesparts]

I would follow a basic plan of action, 1) replace the T/stat, 2) replace the pump, 3) rod out the radiator, and four plan on an engine rebuild. Simply due to the fact that the water was getting into the oil. I also agree with the others that the temp sending unit should be checked. You also stated that you had just finished the work on the wiring, so did you get it all back to where it belongs.

[ozzyracing]

Are all of your hoses tight. I had an overheating issue which was solved by tightening all of my hoses and the problem went away. I am sure this is rare, but ust a suggestion. Before I tightened my hoses, I couldn't see any leaks anywhere, but just keeping the right pressure in the system is important. Again, just an idea that helped me (I also assume all of your hoses are in good condition, just a small leak form one of those and it can cause a lot trouble, and again, you may not see fluid loss).