I have a 5.7 TPI Iroc
I just replaced the motor in this car and it starts to overheat everytime I drive it. It doesn't take long for it to heat up either. What have I over looked?

 

possible water pump, stuck thermostat, bad guage. There are plenty of reasons why this could of happened

 

The first thing to look at is if both fans are running when it overheats. One is turned on by the ECM and one by a switch in the RH head.

 

new water pump, new thermo, original guages. I don't know.

 

I'm with jv9999. I would make sure the fans are turning on when there suppose to or turning on at all. That would make for a fast overheat. If the fans come on, make sure your gauge reads correctly. I have an 89 350 tpi iroc and my temp gauge reads wrong. It will almost be pegged before the fans kick on. I have a scanner that show coolant temp and when my gauge is almost pegged, the scanner shows normal operating temp. Does your engine start to run rough and is it hard to start when it shows overheat conditions? Do you have the air dam/spoiler under the front end still?

 

ok, it does fine when I am at idle but when I drive it it starts to heat up. The fans come on but it doesn't cool down. It starts to miss when it gets like this. It starts back up fine and the front air dam is missing. IF you let it cool down for a bit and then start it back up it starts to heat up agian.

Could he timing have anything to do with it? I have it set at 6 deg btdc. How should I set the timing on these cars? Do I unhook the est or use a jumper wire to the a b on the prom.

 

6 deg should be fine, yes, you disconnect the EST wire to set it. You mean you're missing the air dam under the radiator? It's a must have on these cars. That's probably your problem.

 

ya dont all 350 irocs have a tranny cooler too? that will take away from the cooling effect of air flow from the front opening. so i would say the lower air dam is important. i could be wrong?

 

Well got out there today and started it up and drove it a little. I opened the hood and saw the manifold was red. The temp gets to the last mark before the red and then cools down no lower than the 220 mark. If it idles it doesn't heat up but only when I drive it. Why would the manifold get red like that?

Sorry, the air dam is on the car.

When it is idling and I step on the gas and as it revs down it will stall. It doesn't do it all the time but 3 out of 5 times it does.
It has a hesitation when you tromp on it from a dead stop, once it gets past that it goes.
I did find two wires arching on the metal. That could be the hesitation. I'm going to replace those agian and see if that helps.
All the sensors are new along with the motor. So I'm not sure what else to look for if the wires are not the hesitation.

 

are you sure you dont have an air pocket in the cooling system from when you changed the water pump and filled it back up with coolant ? i had this happen 1 time . try taking the rad cap off and letting the car warm up so the thermostat opens (your gonna spill some out the rad) let it run like that for a few min , shut it off and let it cool back down for a few hrs . then add the correct amount of coolant ..

edit , also make sure your lower rad hose is not collapsing . look in the rad while the car is warm and running to see that there is coolant flow and there are no clogs or blockage.

 

If your exhaust manifolds are glowing, then I'd be thinking either your timing is way off (retarded) or your cat is plugged.

 

I can give that a try. Thanks

 

that was my first thought (timing) but he said its fine . to check the cat , let the car warm up at night and look at it . it should glow like the manifold . also while it is cold put your hands over the exhaust pipes to make sure there is pressure coming out of them ..

 

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did you install right water pump these cars are reverse flow

 

I hope so. I took the one autozone showed for my car. But these guys mess things up all the time. I'll have to check with them and see.