I have been battling with a very illusive overheating problem for moths. I have a brand new 350 HO crate engine, the whole cooling system has been replaced including the radiator.

The truck idle temo is just fine, but when I bring up the RPM to around 2500 or put a load on the engine the temp guage jumps up to 220-240 or so (sending unit in driver side head near front). Finally today we hooked up an analyzer and found that the computer was reading only 180-205 under all conditions (sending unit in Intake manifold). First thougt was bad sending unit or bad guage. Well, no such luck. tried a different sending unit, same thing...guage read hot. Now here is the kicker....I moved the guage sending unit the the other head and the guage read a little less than the computer!! I tried the spare sending unit and got the same results. The only thing that I can figure now is that my driver side head is running much hotter (too hot) than the passenger side head. What the heck would cause this??!!

Maybe a blockage, but where might it be?

Any ideas would be great. Thanks!!

Mike

 

exhaust valves not closing completely valve lash too tight bad head gasket leaking exhaust into coolant passageunlikely unless the heads are aluminum warped head. Exhaust valve not seating correctly (bent valve). take a look at these things i am not familiar of what you already checked.

 

Thanks for the idea. I haven't checked the valves yet, just the cooling system up to this point. I give that a shot before tearing the engine apart. The heads are OEM Vortech heads.

Thanks,

Mike

 

If the inlet manifold gasket is the wrong side down or on the wrong head, it blanks off the coolant flow along the head. This would definately cause the problem you describe.

The coolant outlet in the rear of the heads need blanking, if the gasket is the wrong way around, the front gets blanked, and there is no flow along the head.

Was the manifold already in place?

It sounds like the passenger side gasket is OK, and the drivers side is the wrong way round.

 

Well, thanks for all the input. I'm really hoping that this is the problem because this is really the only component that I put together. It's very possible I put the gasket on wrong. I'll let you know this week...parts should be here any day.

 

Problem solved!

I replaced the water pump with a used one that we knew was good and now she works like a charm.

The brand new GMB water pump that I put on the engine when I dropped it into the truck, was bad. Don't know yet exactly what was wrong with the pump, but I'm going to tear it down and find out. I guess that's what I get for assuming a new item was good, oh well.

Of course I discovered all of the above after pulling the intake
manifold off and replacing every other part of the cooling system. The good out of this though is now I know the rest of the cooling system won't be failing anytime soon.

FYI, vortech heads use unrestricted gaskets on both front and rear. The gaskets work on either side of the intake manifold, they're identical. This also may be why you can't have a weak water pump. The TBI heads however, use restricted manifold gaskets in the rear.

Thanks a bunch for everyone's help, input, and suggestions!

Mike

 

congrats and I hope all works well from here on out

 

Useful info on the different cooling flow on the various heads. Thanks that feedback.

Glad the engine is OK now.