I have a 1976 C3 with a new water pump and new 180 deg thermostat and the car is still overheating even when just idling. even when the electric fans are running at full blast. any sugestions of what else could be causing that?
someone said it could be a blocked heater core if so if I bypass the heater core will that stop the car from overheating untill i can replace the heater core

any help you can give me is greatly appreciated

Thanks
Tony

 

Bad t-stat or possibly fans don't pull enough air is my guess!

 

Did you change anything else?



The heater core has nothing to do with it over heating.

 

A plugged heater core can cause over heating ,, To test my statement go put vice grips on the heater core hose and run your car let me know how hot it gets.

Did you put the thermostat in correctly ? Is the new pump moving the coolant ? Are both upper and lower hoses good and not collapsed ? Is it totally full of coolant ?

 

Tell that to all the people who put a shut off valve in one of their heater hoses.

 

t-stat is opening and the fans are high performance fans their actually over kill for the engine

 

the radiator doesnt really get hot it almost seems like the coolant is trickling through but the water pump is brand new and it was working correctly since it was put in only about a month ago also all hoses are brand new

 

Then the there's something wrong with the thermostat.

 

He just redid everything which is Different then a shut off. If it is plugged he may not be getting the air out of his system ..

 

The t-stat is opening correctly this is why im so confused

 

Huh?

A plugged heater core won't prevent you from getting the air out.

 

How do you know it is?

Maybe something is blocking the flow, or there is no flow.

 

Maybe the new water pump is a reverse flow?

 

is everything new t stat, hoses,radiator?

 

tljr- your later comment that the radiator does not get hot is important. If your temp gauge is showing overheating, the radiator should be too hot to put your hand on. You are not getting coolant flow. So- low coolant level, bad water pump, bad or improperly installed thermostat, collapsed main lower radiator hose or blocked passages in engine water jacket (last is unlikely). Start with the easiest first and go step-wise. 1) with engine cold, make sure the coolant level is completely full. You (or someone) replaced the water pump, so the coolant had to be drained to do that. Check that it was re-filled and all air is out. 2) after the engine is warmed up, make sure the lower radiator hose is round and does not collapse when the t-stat opens and sucks water thru the engine. Better quality hoses have a coiled spring inside to prevent collapse. 3)If hose and coolant level are OK, check if the thermostat is installed facing correctly and is opening. (you said it was opening correctly- how did you check it?) With engine cool, remove the t-stat housing, Check that the t-stat has the metal rod/core toward the intake manifold and that the gasket is not blocking anything, remove t-stat and put in a pan of water and heat on your stove. Put a thermometer in the water and check when the t-stat starts to open. It should start at 180 degrees F. 4) Last check the water pump, even though it is new. Leave the t-stat out but install the t-stat housing and gasket. Start engine and with your hand check the upper radiator hose to see if it starts to get warm as the coolant goes thru the engine and then returns to the radiator thru the top hose. The hose should start to get warm after a couple minutes and should eventually be about the same temp as your temp gauge. If it does not get warm, there is something wrong with the pump or its installation (gasket or something blocking water passage or impellor slipping) This will involve removing the pump- that's why check it last. Hopefully, you will find the problem with one of the easy fixes. Your advice about the heater core is a side issue, most of the water goes thru the engine and many people, including myself have run the car with the heater core bypassed. Hope you get it fixed. An overheating car is no fun. RA

 

yes everything is new except the heater core

 

thank you so much I will do all those things and let u know how I made out

 

This may sound weird but cheek your engine timing. If the timing is off it can make an engine run hot.

 

will do
thanks

 

I'm hoping you find that the coolant level was low. Sometimes it takes a couple warm-up and cool down cycles to get all the air out. You did not say which engine you have, but in my big block there is no radiator cap on the radiator, so all of the level checking has to be done on the expansion tank. It usually takes three cycles to get all of the air out. RA