I have a 1995 cadilac elderado that keeps over heating, it has excessive preasure building up we have changed the thermastate, ran a hot wire to the fan so it always runs , changed tempature sending unite , and water pump also have back flushed the radiator and the engine. what else can we do??

Check the antifreeze level you might have an air pocket in the engine

If the gauge reads hot right after you start the engine, the wire going to the sensor could be shorted to ground.

If the heat and a/c only blows through the windshield defrost vents, it the mode door that is not working. Has nothing to do with the freon in the system. 1986 models may use a vacuum operated mode door actuator or an electronic actuator. Most likely, vacuum. Do not know the exact location, but it is under the dash. May have a vacuum hose loose or the actuator itself could be bad.

it might be your thermastate stuck close because it lets the collant to go into the engine chambers so if your thermastate is stuck is why it is over heating so you can take the thermastate out and test it yourself by putting it into water inside a pan that is on a stove to test to see if it opens up for you but also there are different thermastates out there that have different temperature ranges that you can put in place of that one so go to autozone they will explain to you which one could help you out the most.

Check the radiator fan clutch and be sure your radiator is not full of bugs and dirt.

Have you changed the water pump ?

you need to check fuel preasure and change your fuel filter

it seem that the root of your problem maybe caused by by radiator the heat exchange maybe restricted by dirty fins or corroded passages with in the radiator. This is proven when your temp goes down when your a/c is on. the airflow increases when the a/c fan is on. also make sure your fan turns on high when engine is hot. The heater core problem maybe caused by the removal of thermostat. the thermostat control the flow of cooling water and by removing it it forces more pressure to the heater core thus causing it to fail prematurely. you really need to fix the high temp problem, removing the thermostat will just contribute to more problem not to mention a slow warm up of the the engine (delayed heater reaction) and may contribute to high emmision discharge. The radiator usually cost around $150.00 + 1 hour of labor a lot cheaper than $300 - $500 bill to replace the heater core.

need 1998 northstar engine diagram to change the head gasket thanks

1. In order to eliminate, remove the thermostat altogether, for now.
2. Make sure the heater bypass hose is working. You could route the hose going into the interior heater and bypass the heater also.

It should eliminate a lot!

Next, consider the water pump.

Hope this helps!