7.4 tbi overheating

[blkgmcv3500]

I have a 1987 GMC V3500 pickup truck . Was overheating, blew off side tank of radiator. Replaced radiator, thermostat, coolant sensor at thermostat, waterpump and radiator cap, 16 psi. Also the thermostat is high flow with the air vent hole. Ran garden hose in motor to try to flush for blockage. Also has electric cooling fans which are working, not on sensor but direct wired. Plowed my driveway and neighbors temp stayed at 210 or below. shut it off for about 15 minutes , then went to drive it, made it about 1/2 mile gauge went to 260. Got back opened hood and radiator is gurgling into overflow tank. Also had frontend jacked up over nite in hopes that any trapped air would come out, which it did apparently as coolant level dropped to about 1inch or so below the heater return hose. Any help would be greatly appreciated. Thanks in advance.

 

[squaredeal91]

Seems like it was low on fluids and I would suggest topping it off again and then let it sit to take more water. Sometimes just letting it sit 30 minutes to an hour is enough to let it suck more in. Test drive and Keep checking to be sure it's not taking anymore and if it still persists to get hot I'd look into the possibility of head gasket. I'm hoping it might have just been low and got hot to blow the first radiator.

 

[Turbo4whl]

The thermostat will not open with hot air. If there is an air pocket in the engine it will be at the top by the thermostat.

Several ways to fix this. Fill the engine with coolant through the thermostat hole, then complete the assembly. Easy way, drill a small bleed hole in the thermostat. Sometimes you can bleed the air off by loosening the top heater hose at the manifold.

 

[squaredeal91]

I often drill a small hole in my personal rigs thermostat and it does help out allot. I really like your idea of filling it from thermostat hole too @Turbo4whl

 

[blkgmcv3500]

The thermostat will not open with hot air. If there is an air pocket in the engine it will be at the top by the thermostat.

Several ways to fix this. Fill the engine with coolant through the thermostat hole, then complete the assembly. Easy way, drill a small bleed hole in the thermostat. Sometimes you can bleed the air off by loosening the top heater hose at the manifold.

thermostat has a bleed hole in it .

 

[Turbo4whl]

thermostat has a bleed hole in it .

Another thought, do you have the correct water pump? Serpentine belt spins one way, "V" belt drive spins the opposite way. They each have a different impeller.

 

[blkgmcv3500]

Another thought, do you have the correct water pump? Serpentine belt spins one way, "V" belt drive spins the opposite way. They each have a different impeller.

yes it is. overheated before this and it had original pump

 

[blkgmcv3500]

also only component not replaced was the fan clutch

 

[Turbo4whl]

also only component not replaced was the fan clutch

There were 2 different fan clutches also. Thermo and centrifugal. The thermo type needs to be mounted close to the radiator. They also work different. Thermo type freewheels (still spins) until it locks with heat. The centrifugal is locked until a certain speed, then it unlocks. (also still spins)