ok new to the site but need help have 1996 z28 it has cam,head work,cold air intake msd ignition but its over heating i put new water pump,t stat ,radiator cap,flush radiator,bled cooling system its not losing water not head gaskets cause motor was just built water seems to be flowing good through radiator so dont think its stoped up but i start car and in about 2 min or less its red lined dont think fans are coming on but dont think they will help with it getting hot that fast any advice would be appreciated

 

Did you get the correct LT1 thermostat?

 

yes stock 180 degree t stat

 

Not questioning the temperature rating. Was the type of 'stat specifically for the "reverse cooled" LT1.... not one for an SBC?

http://shbox.com/1/tstat.jpg

If you feel the fans are not coming on, read this:

http://shbox.com/1/4th_gen_tech2.html#cooling

 

is it over heating when city driving or highway? mine was overheating then i noticed that i was missing that flap that goes under your front bumper i guess that is there to direct air up in to the bay and in front of the radiator

 

I had an overheating problem a while back where the Temp Sensor for the Gauge (in the front of the block) snapped. It shorted out and also blew the under hood fuse.

The blown fuse also controlled the fans as well, so check that as well.

 

Some bad info.

The temp sensor for the coolant temp gauge is NOT "in the front of the block". It is on the driver's side head, between #1 and #3 spark plugs. The temp sensor on the front of the engine - actually on the water pump housing - is the sensor that feeds the coolant temp to the PCM, so it can use the info to control the engine and the cooling fans. That sensor pulls 5V power from the PCM. It is not on the same fuse as the fan relays.

The instrument panel gauges are fed from the fuse labeled "GAGES" in the panel on the end of the dash.... does not supply power to the fan relays. The fans themselves are protected by a fusible link in the wiring, not a fuse in a panel.

 

Possibly a plugged heater core? Although i think it would just throw sh***y heat but might be something too look into
U

 

Thanks for correcting it was a while ago and I tried to go by memory without actually looking at the car

But definitely could be related to the issue at hand

 

I checked t stat it is for lt1 changed both temp sensors and flush out heater core still over heating in process of getting fans running the car ant left shop sense i got it back together because of it over heating

 

Are you sure you used the correct LT1 head gaskets, and not the Gen 1 SBC gaskets?

 

mostly there to keep as much air as possible from going under the car at high speeds, but they realized that high pressure spot it created would be perfect for a radiator intake.

 

Did you check the oil to make sure it isnt milky? As mentioned, possible wrong headgaskets or even a blown headgasket if the machine work wasnt done properly.

-Scott

 

Even if theres no water in oil and i ant loosing no water could head gaskets still be blown because i got the fans running and its still over heating

 

Did you test the new thermostat before putting it in the car? I know you said it looks like its flowing well but maybe you should pull the thermostat out and throw it in a pot of water to see if its working.

Was the radiator neglected? Prestone radiator flush won't do much to clean a radiator but their radiator cleaner will. Napa also sells a good radiator cleaner. I believe the part number is mac 1400. Its a solid instead of a liquid. If it was really bad you might want to take it to a radiator shop to be cleaned.

I would bleed the system again. Radiator caps are cheap. You can pull the connector for the maf and start the car to see if your fans are working.