98 Overheating Again

[ptcfast2]

1998 Cavalier 2.2L OHV

I've been trying to deal with a 2.2L that is overheating for no apparent reason. The engine was recently rebuilt (thought the head gasket blew). Turns out the head gasket was fine, so I rebuilt it, put new gaskets in it, etc....

So, I've been driving it around without a thermostat as the car overheats if one is in it. Today I finally decided to put it back in, and low and behold the car starts to run hot. (This is a NEW thermostat by the way).

The car hovers around the 1/2 mark on the gauge at idle, temp increases to 3/4 of the gauge as you put load on the engine/drive it around. Heat output only happens on 3 of the 4 vents (Driver Left - Hot, Driver Right - Warm, Passenger Left - Warm, Passenger Right - Cold), and all hoses seem hot EXCEPT the lower radiator hose by the thermostat housing. The lower hose is luke-warm but not hot like the others.

I'm starting to guess I've got a clogged radiator which can't move enough coolant fast enough. I'm also thinking the heater core due to the vent/heat issue, but I'm unsure if that's really the case due to of some vents getting hot and others getting only warm? Never had that happen before....

Any suggestions?

[Jmrec100]

If its not a clogged radiator (guessing its not), its because the cooling system is not completely purged. I HATE chevy for no radiator cap etc... Its a common problem.
What I did was, pull the front horizontal hose that leads to the top radiator. Fill until water comes out. Then quickly put the hose back on. Then I disconnected the hoses one at a time, from the overflow tank and with a funnel pour water into it. Did it for each one except the bottom hose on the overflow. It should fill on its own. Squeezed the hoses everywhere. There is a bleed screw on the driver side in the metal tubes for the heater hoses , below the coil packs. I loosened it. Squeezed hoses, closed it on the squeezed hoses. Loosened my grip on the hose. Squeezed again with the bleed screw open-then close. Repeat repeat repeat. This not being completely purged is a common problem. I also had an electric heat gun that puts out high temp and directed it at the t-stat housing to open it sooner. Squeezed hoses, etc etc until both upper and lower hoses were same temp. Let it cool, then repeat it. I have a hard time getting it completely filled but this works for me.
Also, since these cars tend to run hot and will overheat in hot weather when stuck in traffic, I put in a bypass switch to turn on the electric fan manually when I need it.
Do check if your fan is really turning on.

[ptcfast2]

Originally Posted by Jmrec100

If its not a clogged radiator (guessing its not), its because the cooling system is not completely purged. I HATE chevy for no radiator cap etc... Its a common problem.
What I did was, pull the front horizontal hose that leads to the top radiator. Fill until water comes out. Then quickly put the hose back on. Then I disconnected the hoses one at a time, from the overflow tank and with a funnel pour water into it. Did it for each one except the bottom hose on the overflow. It should fill on its own. Squeezed the hoses everywhere. There is a bleed screw on the driver side in the metal tubes for the heater hoses , below the coil packs. I loosened it. Squeezed hoses, closed it on the squeezed hoses. Loosened my grip on the hose. Squeezed again with the bleed screw open-then close. Repeat repeat repeat. This not being completely purged is a common problem. I also had an electric heat gun that puts out high temp and directed it at the t-stat housing to open it sooner. Squeezed hoses, etc etc until both upper and lower hoses were same temp. Let it cool, then repeat it. I have a hard time getting it completely filled but this works for me.
Also, since these cars tend to run hot and will overheat in hot weather when stuck in traffic, I put in a bypass switch to turn on the electric fan manually when I need it.
Do check if your fan is really turning on.

Thermostat is good (just boiled it to confirm), fan comes on when it gets too hot. The lower hose is the one that's always colder then the rest (which I would assume is correct as it delivers cold coolant back to the engine). I've also got the car filled with water for the moment. I'll go and try your method and report back.