My engine is still running hot. I am not quite sure why it is still boiling. I checked the timing yesterday and its actually running a little bit retarded. I noticed last night that the heat isn't nearly as hot as it used to be. Could a clogged heater core cause overheating? I heard a simple way to flush it is to reverse the hoses. Does that work? What about just blasting it out with the hose? Could it be the cap? I'm using a 16 pound cap. I'm sure it is holding pressure because it holds in the boiling water

Retarded timing will cause it to run hotter than it should.
Don't think a heater core would cause it
Do you know that the gage is right?
Does it push the water out?

mopar.mopar@gte.net

Is your radiator full when the engine is cold? Have you replaced the thermostat recently?

snarl@net-change.com

No the heater core can not cause overheating. Most AC equiped cars shut off coolant flow to the heater core when in full cold setting. Industrial Slant 6's never had heater cores connected to them when they were used on forktrucks, swathers (hay cutting machine), generators, etc.

cfield@ll.net

There are a couple of factors that can cause your engine to run warm.

Flow of coolant. Each engine is designed to have the coolant flow thru at a specific rate. Anything that will either speed up or hinder that flow will change the operating temp. of the engine. Let the coolant stay in the engine to long and it will run hot. Let it pass thru to quickly and …hmmm…not sure if it would run hot or colder. So ask yourself if there is anything that is hindering the flow of the coolant. Could a plugged heater core hinder the flow? Well maybe, so check it out. Other things that can affect the flow are a bad thermostat or gunk build up in the block. Is it time for a good flushing of the block? Another thing to check is if the water pump is pumping enough fluid fast enough.

Size of cooling surface. The engine was designed to work with a certain size of radiator. If someone put in a smaller one then you won't get the cooling surface needed to keep your cool. The other thing that can affect cooling surface size is a plugged radiator. If the center of the radiator is plugged with gunk then the coolant is only around the edge and you loose that large inner surface of the radiator face. Run your engine up to normal operating temp and then shut it off (turning off the engine is important in this test). Now put you hand carefully on the center of the radiator. If it's cold to the touch then you need to get it fixed. If it's hot, it's fine but watch out that you don't burn your hand.

I'm not sure if reversing the flow thru the core will really flush it or not. I'm thinking not because if there's not enough pressure to blow out the gunk when flowing one way I don't think there'll be enough to blow it out the other. I have used a garden hose to blow out the gunk in a heater core. You do have to be careful that the pressure from the hose does not blow the core out though. If you're not getting the right amount of heat from the heater then this is a good indication the core is plugged.

Remember that a warm running engine is only a symptom of the real problem. Putting in a larger fan or radiator or a cooler thermostat may cause the engine to run cooler, but it would not have fixed the problem. If you want to fix it right then find the root cause and treat that.


ejones@seanet.com