Running hot

rgatijnet1 wrote:
I guess it might have a lot to do with the air flow across the radiator for the different coaches. I know some do tend to run hotter than others because of the design of the front cap.

That might have been the explanation - my memory isn't what it was. The fan, when working properly, draws air through the radiator even at highway speeds. The design of the front cap might otherwise allow the air to go around the radiator.

turbojimmy wrote:

rgatijnet1 wrote:
Usually at highway speeds, neither the electric or clutch fan have too much affect on the temperature. The highway speed usually means enough air is moving through the system to keep things cool.
Since it is getting hot at both idle and highway speeds, it could be an air bubble in the system, a plugged radiator, a collapsing hose, or something else other than the electric fan or mechanical fan clutch.

I posted the same logic, and was corrected (though I don't recall the logic), when I was having cooling issues last year. I assumed that since it was getting hot on the highway that the issue had to be something other than the fan. But, even at speeds 45+ there is a dramatic difference in temperature with the new clutch. I can hear it roar at those speeds when it needs to.

I just recently replaced my fan clutch on my 8.1L GM engine. At highway speeds, unless I was climbing, the temperature was normal even tho I was pulling a toad. The only time I noticed the engine running hot was when I was stopped or moving slowly through city traffic.
My fan clutch would kick in and roar at 207 degrees when it was good so I knew it was the problem. I ordered a replacement fan clutch and had it shipped ahead to my next stop. While on the highway, for the next 250 miles to my destination, everything was fine and the water temperature stayed in the normal range.
I guess it might have a lot to do with the air flow across the radiator for the different coaches. I know some do tend to run hotter than others because of the design of the front cap.

rgatijnet1 wrote:
Usually at highway speeds, neither the electric or clutch fan have too much affect on the temperature. The highway speed usually means enough air is moving through the system to keep things cool.
Since it is getting hot at both idle and highway speeds, it could be an air bubble in the system, a plugged radiator, a collapsing hose, or something else other than the electric fan or mechanical fan clutch.

I posted the same logic, and was corrected (though I don't recall the logic), when I was having cooling issues last year. I assumed that since it was getting hot on the highway that the issue had to be something other than the fan. But, even at speeds 45+ there is a dramatic difference in temperature with the new clutch. I can hear it roar at those speeds when it needs to.

Usually at highway speeds, neither the electric or clutch fan have too much affect on the temperature. The highway speed usually means enough air is moving through the system to keep things cool.
Since it is getting hot at both idle and highway speeds, it could be an air bubble in the system, a plugged radiator, a collapsing hose, or something else other than the electric fan or mechanical fan clutch.

A couple of thoughts... be sure the hoses are firm to the feel and not spongy. If the bottom hose is soft, it may be collapsing at highway speed. If the pump isn't leaking, it may be okay as I haven't personally seen an impeller fail without the seal leaking as well.
With the engine cold, or just slightly warm, remove the radiator cap and verify water circulation with the engine at idle. This would indicate the pump is moving water at least at idle. If the radiator takes a big burp while the cap is off, it may indicate there was a vapor lock in the cooling system.
Lastly, if it is cool at idle but hot at speed, it may indicate the radiator is not flowing properly and may need some attention.
Good luck,
Gary

Lititz55 wrote:
It does roar when you leave a stoplight for maybe
two minutes not long enough for temperature to come down

Thank
Jim

I don't know how an electric and clutch fan are designed to work together so I can't tell you the consequences of one not working verus the other. My RV is old and just has a mechanical clutch fan.

I do know this: my fan would roar when it seemed like it should but my 454 was still getting hot. I replaced the fan clutch and it made a HUGE difference. No more getting hot except for long, steep grades. Under these circumstances getting the RPMs up (so the fan can do its work) cools it right down.

I would do a flush and fill. I have seen a water pump where most of the blades were eaten away from corosion due to lack of maintaining anti freeze.

It does roar when you leave a stoplight for maybe
two minutes not long enough for temperature to come down

Thank
Jim

Its electric and clutch fan
Its hot at idle and highway

Thank
Jim

Make sure the engine base timing is set correctly and that the timing advance in the distributor is working correctly.

Since you have an infra red thermometer, you should be able to aim it at different parts to see what is hot. Make sure the radiator, air conditioning condenser, and oil cooler are all free of bugs and debris so that air will easily pass through.

When does it overheat? Highway driving? slow speed? pulling hills?