96 Suburban W/gauge Issues (please Help)

[dlowe402]

Hey there, I am having an issue with my 96 Suburban. It's got the 5.7l vortec and the temperature gauge is doing weird things. The reading will skyrocket and then come back to acceptable range. It will do this repeatedly but the engine is not overheating, nor is it running any different. The only thing affected is the heater. When the gauge goes up, the heat goes away, like it's shutting a valve to the core. When the gauge goes down, the heater blows hot again. A buddy told me he thought it sounded like a temp sensor that was faulty but how is it changing the heater temp. Is there an electric valve or gate somewhere that is turning the water to the heater core off or what? I have worked on a lot of older cars but all the sensors and stuff are a little confusing. If anyone could point me in the right direction, I would greatly appreciate it.

[Zembonez]

Have you done and cooling system service work recently or noticed any coolant loss? It sounds like you might have a pocket of air in the cooling system.

[dlowe402]

Have you done and cooling system service work recently or noticed any coolant loss? It sounds like you might have a pocket of air in the cooling system.

 

 

About a year ago, I changed the water pump. After it started doing the above problem, I also noticed a squeaking noise from the water pump, so, thinking that it was bad again, i took the old one back and exchanged it(was under warranty). This time, I replace both the pump and the thermostat. Still does the fluctuating thing. What is the best way to get an air pocket out and I will try it. At this point, I'm not ruling anything out. Thanks for the post.

[d3athsong]

My 94 s-series jimmy does the same thing. It has done it for probably the past 5 of the 6 years ive owned it. Temperature stays constant even though the guage spikes into the red. Havent been able to come up with a solution.

[dlowe402]

O.K. I must say, I think Zembonez nailed it. After I replied back asking how to get the pocket out, I went out and messed with it. I basically opened up the rad cap and started filling it slowly. Once it ran over, I turned the engine on and let it warm up. As soon as I felt that the thermo had opened up, I began pumping the upper hose. Don't know if it mattered or not, but I kept seeing bubbles in the radiator. I kept filling and letting cycle for several minutes checking to see if the fluid level would go down. When I could see that it wasn't, i took it for a drive to see if I did any good. Apparently I did because now the heater is running me out and, while I am getting a little fluctuation on the gauge, it is nowhere near as drastic as it was before. I think I need to just keep at it to work it out fully. I do want to than Zembonez for an extremely rapid response. I, however, feel like an idiot for not checking that first.