Hey guys, I rebuilt my engine last fall with 11.5:1 comp pistons, a cam, rods ect. Anyways since the build when Im stuck in traffic or at idle when its warm outside it just starts overheating. Like the gauge goes all the way into the red. But as soon as I start driving at like 30-40 mph it cools down. It never did this before, and I dont know why its happening.
BTW- The fans come on, the coolant level is full and i replaced the rad right before the build. Any ideas?

 

BTW I just replaced the thermotat a before the build, and both rad hoses are hot when the engine is running

 

Is the coolant circulating good?

 

Could still have air in the system...

 

There is no air in the system either. its been bled

 

Does the fan come on (sounds like it's not)? Could be a bad fan switch...

 

Sounds like the fan isn't turning on.

 

I have stated that the fans come on. I physically got out of my car, popped the hood while it was running to check.

 

I was having overheating problems last year, with everything (thermostat, fans, properly bled, new rad cap etc) working just as you said, to me it sounds like your rad is just past due. replace the rad if everything else is working. I put a nice koyo in mine.

 

The rad was just replaced

 

Did you check the water pump when you rebuilt the motor? Maybe the bearing is going bad and it is not turning enough at idle. If that is happening you should be loosing coolant thru the weap hole on the pump.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike3 &raquo;</TD></TR><TR><TD CLASS="quote">I have stated that the fans come on. I physically got out of my car, popped the hood while it was running to check.</TD></TR></TABLE>

It sounds like you have checked everything already, but it can't hurt to check again. A cooling system is not that complicated and it has to be one of only a few things...

 

i would say pump too. when you rev, pump rotates faster (forcing it to run faster even if pump is failing), therefor cooling when car at higher rmp. when at idle, less rpm, therefor not sufficient fluid movement at pump to cool car? does that sound possible?