cooling ?

[ONE BAD BLAZER]

my 94 4.3 CPI has a cooling problem at idle only it over heats it has a cam headers e-fan HD waterpump 160 stat a stock radiator any sugstyons

[rat]

Cooling fan problem if it is only when you aren't moving. More info about your fan setup?

[chesspirate]

Is the radiator cap working properly? Cheap fix

[ONE BAD BLAZER]

how would i find that out

[chesspirate]

Just buy a new one, less than $10.

[Maximus]

What kind of fan are you running and using to control it.

[ONE BAD BLAZER]

it a fan off my 89 T/A with a 350 tpi and it comes on when the key is turnd on so its on all the time and it wont overheat when it is moving

[89VORTEC]

Well if your fan is running full speed all the time, and you are sure the fan is not shutting off, then i would first change the stat. Even if its new, it doesent mean something didnt shift or warp in it, keeping it from opening.

Also what tells you its overheating? The gauge or the coolant boiling out? Or both?

If its overheating to begin with, i doubt it would be a rad cap. The cap is designed to suck antifreeze from the reservoir as the engine cools, and to push excess coolant back into the reservoir as the coolant warms up. Usually a bad cap would just cause an overflow (cap not holding pressure), but wouldnt be the actual cause of the overheating unless it is creating a low coolant condition.

There could also be a chance that you are pushing compression into the cooling system due to a bad head gasket.

And this ones off the wall, but how old is your water pump and how clean is your antifreeze? Rusty antifreeze will eat up water pump fins pretty quick (3-5 years?)

[ONE BAD BLAZER]

the water pump is new hevyduty and the antifreezer is all new no rust has also rectally been fulsht out the only thing that has not been changed is the radiator its 12years old

[89VORTEC]

First try a new thermostat.

Then take the cap off, start the truck from cold, drink a few beers, and start watching inside the radiator right at the temp that the new thermostat should open. If your cooling system is flowing properly, you should actually be able to see the antifreeze moving or flowing. Too bad the trans cooler is inside the rad right there. Sometime you can actualy watch the flow right from the cores into the side tank.

The only other thing beside a pump not working correctly, that directly involves flow, would be a clogged radiator.

Once you have checked everything else, you might consider head gasket. The only way to know is to do a compression test.

What were the conditions the first time it overheated?

[Maximus]

I have seen cheapo thermostats be bad right out of the box.So I agree check it to see if it's opening.If it is a elcheapo then buy a good stat that will perform good.Im pretty sure yours can use a older smallblock V8 style T-stat.If so I recommend ordering a Mr.Gasket high flow T-stat.Most off the shelf T-stats are cheap and don't start opening really till about 15 degrees after they should.The Mr.Gaskets open almost on the money at what ever they are rated at.They are Copper/Brass and are the best buy for the money in my opinion.And just like they advertise they open when they should no matter what RPM you are at.You can get them in 160'/180'/195'.Also you might wanna get the radiator rodded out and a good acid flush to make sure the radiator is flowing to it's best capability.You would be suprised what a difference it can make.You just don't know what kind of blockage and debris is inside that radiator that a good acid flush will bring out.

[ONE BAD BLAZER]

the first time it overheated i gust put the cam and headers on it. and every thing on the cooling system but the rad. is new

[Maximus]

You mess with the timing any?

[ONE BAD BLAZER]

timing is dead on

[Maximus]

Get that radiator rodded out or acid flushed.You will notice the difference if yours had blockage before.