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another overheating question

C

csbuckn

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Now I know this question has been asked before but I cant find the answer.

I have a 91 suburban 4X4 with a 350 TBI and its overheating. I've put in new head gaskets, intake gaskets, thermastat, water pump, radiator and bypassed the heater core and it still overheats. When I start the truck, it overheats. If I have the radiator cap off, the needle stays around half way. When i close the radiator cap, the upper radiator hose gets hot and builds up ALOT of pressure and the truck overheats. The weird thing is that the lower radiator hose stays cold the whole time, even when it overheats. The next thing I was gonna do is take it to the shop so they could tell me whats wrong and I could fix it but wanted to see what yall say. If I had to quess I would say the new water pump is bad. It just seems like the fluid is not flowing through the motor
 
T-stat problem. Either in upside down or bad out of the box...try removing it entirely and see what happens.

Rene
 
Make sure it is the correct water pump, these are reverse rotation because of the serp belt set-up and the fan is also reversed blades.
 
now that i didnt think of. now the new water pump looks exactly the same, is there a chance that it could still be the wrong one
 
There is a chance, they look identical from the outside. The impeller on the inside is what is different.

Also, are you running a fan shroud?
 
is there anything else that you can think of? even though that sounds like exact problem.
 
I'm pretty sure this is your problem. With the wrong water pump the water will just cavitate and not flow. This would make the lower hose cold and the upper hose very hot.
 
Could also be the intake gaskets are on wrong. If you put the blocked port to the front, It will overheat quickly.
 
4X4HIGH said:
On conventional SBC the ports are open on each end.
Click to expand...

not on mine they weren't,,,thought it was kind of weird too, but the rear port only has a little steam hole.

Even the old one was like this from 1989
 
yea i think mine went on only one way but i did block the rear ones. the gasket set i got was kinda dummy proof. it had arrows and said this side up.
 
csbuckn said:
yea i think mine went on only one way but i did block the rear ones. the gasket set i got was kinda dummy proof. it had arrows and said this side up.
Click to expand...

YUP, and mine went the extra step,,not only did it say "this side up" but it also said "this side rear"

and I STILL didn't catch it !!:doah:

thankfully Jason was there to see it:D

i just wasn't in the mood to work on it anyways, but i'm glad he was there to help push me along, now it's almost done:D
 
One more quick dumb question. when I turn on the 4 wheel drive, do I turn the hubs to lock or free. when I got the truck, the prev. owner had it on 4 wheel drive and free but that dont seem right.
 
"free" means the hubs are unlocked, no pulling power going to that wheel,,,"locked" means they will pull. The hubs are "locked in"
 
so i got the right pump but it still does the same thing. is there a way you can tell if the intake gaskets are on wrong or can you put the head gaskets on wrong. how do you tell which ones are bad
 
do you have a bypass hose that is supposed to run from the intake, by the thermostat, to the top of the water pump?
 
He says it's on his '91, so it shouldn't, that is usually plugged up, and if it is used it is for heater core use.
 
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