97 PA Cooling Issue

[Bryan22]

In short....The water pump went out, the rad also had a leak and replaced.

Now, after replacing those the engine tends to heat to a higher temp than what it should...really high. The return hose will sometimes "suck in" from vacuum. What is happening here?

Thanks!

[HotZ28]

Did you bleed the system after filling with coolant? How about the thermostat, is it opening?

[Bryan22]

I have done my best to purge the system of air. I do get coolant coming out of the bleeder fitting on the top of the thermo housing.

[HotZ28]

On this particular car, the radiator fill neck is higher than the engine, so therefore the bleeding process is somewhat simplified. I usually fill the radiator while cold, with the thermostat bleeder open until coolant flows out the bleeder, then close the bleeder. Keep filling the radiator until it is completely full, then install the cap. Start the engine and let it run until it gets warm. Set the heater control to HOT, so coolant circulates through the heater core. After the engine starts to warm up, crack the bleeder valve at the thermostat housing again and see if any air/steam escapes. If not, you're done. If it does burp air/steam, keep working the bleeder until you see only coolant flowing. Let the engine cool down, then top off the radiator once again. Be sure to keep the coolant level in the overflow tank at the proper level and check it for several days after this process. The whole process is similar to bleeding the brakes! With air in the coolant system, your cooling system will have steam pockets, and in turn will cause “hot spots” and this will also give erratic coolant temp sensor (CTS) outputs.

Sounds like there is still air in the cooling system.