Overheating problem!

[JanneB]

I just cannot figure out this problem: The temperature outside is -4 fahrenheit and my truck is overheating in park idling!!

The engine is a new 502 with -69 ovalport closed chamber heads and was installed 1 year ago. The heads were checked before installing. The overheating problem started when I drove through muddy waters (not the band). Because the old radiator had a minor leak I installed a new aluminium radiator (Allstar All30016 19"x31").

There is not room for a mechanical fan so I used an electric fan with a shroud, just as I used with the old radiator.

The thermostat is 180degree and the water is sirculating, but not only does the upper hose get hot, so does the radiator and the lower (return) hose!!

The ignition may be a little off but there was not a problem like this with the old 4 rowe radiator, the new is 2 rowe (wide rowes).

There is no bubbles in the water when the cap is off and engine running.

Yesterday, for example, (-4 temperature) I went for a test drive. At 180 the thermostat opened and I drove maybe half an mile at 20 mph (2000rpm). The temperature was 186.

I put it in low4wd and drove with maybe 1000-1500rpm and the temp slowly rose to 196. Tried to drive a little faster with 2000rpm and it still rose to 209.

Got back to the road and with a speed of maybe 30mph the temp got down to 180 again.

Is the radiator causing this? Can it be that bad or maybe cracked heads?
There is no oil in the water and no water in the oil. The water is not disappearing from the system, the radiator is allways full.

 

[southernspeed]

Is your fan pulling air through the rad rather than trying to push it back out the front ?(wrong fan rotation). Is your guage correct? You say there is bubbles in the water(coolant I hope!!) but with the cap off the coolant should overflow long before it's overheating.

 

[1-ton]

You could have a defective thermostat, with a weak or broken spring. Make sure the lower radiator hose is not collapsing. These things can cause intermitant water temp problems.

 

[Cricket]

Drive slow it overheats
Drive fast it cools down

Sounds like an airflow problem to me.

 

[JanneB]

The fan is mounted behind the radiator and it is pulling.

It was the biggest I could find at the moment, 15".

One time I let the temperature rise to something like 230 and the coolant (50/50%) was boiling in the expansion... I forgot what it is called but you know what I mean. I believe the gauge is correct, and the return hose is hot.

Airflow might be the problem but at idle and -4 fahrenheit?

The waterpump is also new, I have serp belt and it is turning the right way, I checked.

 

[rick88blaze]

Might sound like a dumb question, but did you get a reverse flow water pump when you put on the serp. setup?

Rick

 

[Chaddy]

my buddy has a 71 nova with new heads yada yada...anyways he said ever since he put it all together it ran 10 -20 degrees hotter. About a year later he took it in to a shop just to get the temp taken and the gage was reading hotter than it should.....put in a new gage and it read correctly.