My engine has been overheating and I have replaced the thermostat and coolant temp sensor in the head but no dice. The radiator hoses stay cool as the engine heats up and I cannot bleed the system, water never comes out. The waterpump was replaced about 18 months ago and it is not leaking or whining, is it possible it could still be my problem?

My heater core has been leaking for a week or two but today I connected the two hoses that go to it together. I don't know if this has anything to do with the overheating.

Also my fans won't come on by the PCM, but I can turn them on by my fan switch. I had a code 43 that has something to do with the fan 1 relay so I switched the relays around but they still will not work.

Any ideas? Thanks

 

On my 94 a 43 code means there is a problem with the knock sensor.

As far as the heater core leaking, anytime the cooling system has a leak, you introduce air in the system. Lt1's are notorious for being air bound. How long after the heating problem did you notice the heater core leak? Or vice versa.

The fans need to come one at 212 or something like that. You need to look into that also

 

Just curious, you put a thermostat in that goes with the LT-1, right? Needs to be reverse flowing.