258 overheat

[montylnc]

New to the site, thanks in advance!

'83 CJ7 AMC 258 i6 / 4.2l , cam, Weber, header, no emissions. On the way to work, she started running 225 degrees, normally at 195. On the way home, 250 degrees. Replaced thermostat, cap, and power flushed the coolant. Still at 225, but cools to normal while going uphill at 1500 rpm. Gets hot on level ground at all speeds.

Tried to measure coolant temp in top of radiator, but it doesn't overheat until the cap is back on?

Has a stock style fan and shroud, no fan clutch. No play in the pump, no leaks anywhere.

What is going on?

 

[IOPort51]

when you were trying to check the temperature was there water circulation once the thermostat opened up??

 

[montylnc]

The level rose and started overflowing a little. I couldn't tell if there was actual flow.

Also, should the lower radiator hose be hot? Seems that it would if the motor is hot and the system is flowing.

 

[CJ]

Is the spring still (not rusted out) in the lower radiator hose? Many times when driving as the RPM's increase (if the lower hose spring is missing / gone), the hose will collapse decreasing the coolant flow.

 

[montylnc]

I'll replace the hose next.

Why would the temp return to normal while pulling a hill? I can coast at the same speed and RPM, and it goes up. Seems backwards to me.

Without a fan clutch, is this a radiator blockage?

 

[montylnc]

Update: The radiator was clogged. Shop is boiling it and will be back together Monday. I replaced the hoses and water pump anyway, since I'm there.

Thanks for the input!