Ok i have a 88 Chevy PU that I just rebuilt the heads on. After finnaly getting everything back together and lots of lil problems its running, but the temp runs about 235 just at idle. The things ive done to try and fix is,
*Installed New factory Thermostat
*Installed new REVERSE ROTATION water pump
*Flushed out radiator
*Installed new water temp guage and sender

After warming up to even around 225 the upper radiator hose is COLD. The lower radiator hose is slightly warm, and the outter shell of the rad is warm. Causing me to think that its the wrong water pump. However numerous net seachers leads me to belive i have the correct one. Its a serpentine belt system. Pressure builds up good in the radiator and heater hose get hot. Could a big air pocket be part of the problem? Could i have possible installed the new thermostat in wrong direction (spring side down)? Never had an overheation problem untill now either. Thanks for your time and much help is needed.

 

TTT

OK so I found out Murray Thermostats are complete junk!!! Orileys only sells that brand here. And the guy in the store said NOT to buy it. ALOT of complaints on them. So i bought one from autozone for like $9 bucks. Same problem. If I run without the thermo it wont even heat past 120*

So i put a stant thermo in and it heated up to about 220 and if i drove it, it would drop to about 200. Took it to shop and had exhaust welded up on it. And drove it home and it got hot again. The top radiator hose was cool again. I have a 15lb pressure cap on it. Would that maybe affect overheating?

Thanks

 

This is a F-Body board - have no idea on the trucks. F-body serp systems use reverse rotation pumps, but again - no idea on the trucks.

Suggest you locate a truck website to be sure you get the right answers, as we are all F-body folks here and there's no telling what bad info you might get since you have a truck.

 

Reverse flow is correct for your year...serp system
T-stat spring sits in manifold, pointy end up towards housing
Your heater returns to the rad, not the pump...correct?
Takes that top hose longer to heat up because of that
System should be burped if you have a return to the rad

If you are unsure you got all the air out, pull the stat, fill the manifold, re-install the stat and idle the motor until the rad stays full, then lightly bring the rpm up, fill the rad while holding the rpms and cap the rad.
Couple of days driving will burp the rest of any small air

By the way, easiest to burp system with truck facing uphill

 

just wondering if you made sure that the cooling fan(s) are turning on

 

If it's stock, he has a nice big cluch fan and an even larger fan shroud

 

just a thought

 

lol Almost a month and no response then 5 posts in one day!
And the only reason I posted on this site is because ive been on it for years and have put trust into the poeple here! Besides I dont want to spend hours looking for a decent truck forum for a SBC cooling problem!

Anyways Its a cluth fan and im about 99% sure its a reverse rotation pump.
Every thermostat ive installed was spring side down. And I filled the manifold before installing the new thermo. Even jacked the truck up on stands trying to burp all the air out.

However After building pressure the top hose might be slighty warm and if I hold a rag over the radiator cap and unlock it, it burps alot into the overflow tank. And Ive done reved it up and dumped aniti freeze in and capped it. I just dont understand what it would be! Does there need to be antifreeze in the top hose before the thermo will open? The top hose is a bit higher than the rad. cap not letting me fill it very easy. It seems as though the thermo opens but all the air doesnt get out of the top hose. But not 100% sure on that. Whats next? Replace truck for another Camaro?! lol
Thanks Everybody!

 

The tstat wont open unless there is hot coolant behind it, that means if there is air in it it wont open. They usually put a little hole in the thermostat for just that reason. It is possible the parts store gave you the wrong or defective water pump. Try raising the front of the vehicle, and run the engine with the radiator cap off, keeping an eye on the temperature gauge to make sure it doesn't overheat. You could also try running it without the thermostat, if there is no flow then you know its the water pump not the tstat.

 

i always drill 2 small holes in my t-stats for this exact reason, I know someone else that pushes his tstat open an sticks an advil in it, so the system allows coolant to constantly flow for like the first 10 minutes and burps out real good

 

Advill huh? And to think all this time I was eating those and always wondering why my headache didn't go away (I usually blamed my boss). But now I know - their for the car!

 

hey I don't do it, but my buddy does, he's been doing it for years, claims it works like a charm

 

Have you resolved your concerns yet?
Give us an update

 

I've been drilling a 1/8" hole in domestic t-stats as well for, well, forever
I just drill one. It's enough to stop thermostatic shock
Before I came along the Real old-timers used to wedge the stat open with a sugar cube
I still run my personal chevs to this day with a hole, even if it's a 195 Degree with it's own little v-groove
If it's a customer's vehicle that I know is a bear to bleed it definately gets a hole

FYI, make sure you drill it inboard of the gasket

 

ok someone please correct me in a hurry if i am wrong, but to try and isolate the problem could you not try to run it with no t-stat just to see if it would overheat, or is that going to be way to open
i know at work we run engines with completely open stats for cooling tests

 

he could, but from what he is saying it sounds like his manifold coolant level is just shy of the t-stat, plus he never responded back, he probably fixed it and is done with us

 

eh.. good point
thought i would throw it out there

 

any updates?