I bought an 88 Iroc from a guy that had recently rebuilt the engine....it has a 5.7L TPI. He told me that he was fighting overheating issues but finally got it resolved. I always noticed while in stop-and-go traffic the engine would heat up to almost 230 on the installed aftermarket TEMP gauge which made me nervous.
I had a Chevrolet dealership replace coolant in the radiator to ensure it was a good 50/50 mix. When I left the delearship it was ~90 degrees outside and while I was driving on the interstate with the wind (wind at my back) the car would heat-up to 230 - 240 but when I turned and went into the wind it would cool back down to around 200.

The guy I bought it from said he replaced all coolant related parts and I can see that the radiator is brand new, fans work but I'm not mechanically inclined so I don't know what else can cause this?

I've heard that rebuilds run hot but it shouldn't run this hot right?

Any help yall can provide is greatly appreciated.

 

If its running stock programming, stock rad, stock fans, stock thermostat setting and stock fan switch, then yes on warm days it can very easily hit 230. I have seen 240 on mine and i turned heater on which reduced temps surprisingly. I guess running thru heater core helps reduce heat.

If you want it cooler, try a lower temp stat and lower temp fan switch. Other fan needs chip tuned to turn on lower or else put it on a switch to overide. Once done, shouldnt see over 200

 

Thanks for the information......He had both fans wired such that they are always on when car has power, no fan clutch. I talked to him and he said that he replaced the thermostat and installed the bottom air dam as well....so I'm out of ideas.

 

Coolant system filled properly with no air bubbles? Did he flush rad or replace stock rad?

Whats timing set at on the motor

 

I just had coolant flushed at Chevy dealership yesterday....how do you know if there are air bubbles? He told me that the radiator is correct size for 5.7L.

I'm a bit embarrassed I don't know how to check the timing.

 

Air pockets can get trapped in some areas in the system and create hot spots. If it was flushed and filled by dealer it should be done correctly and most all air removed. Not really sure how to check for air pockets other than cyling fluid thru with cap open and keep checking for bubbles and listening for them. Some driving various hills and turns usually works them all out. Keep checking fluid level

Timing you need a timing light and follow instructions.

Radiator should be around 31" wide by 19" tall or so

 

I would make sure the fans are pulling and not pushing the air

 

Yup the fans are pulling air from the radiator towards the engine. The only other thing I noticed is that the air filters are filthy......guess he hasn't replaced them in some time. I will replace those bit doubt that will fix a cooling problem.

 

I would first check the gauge and make sure it is accurate,before tearing everything apart.