Posted by Ben on September 28, 02 at 13:35:32:
In Reply to: Re: 88 K3500 454 TBI runs hot posted by ralphie on September 28, 02 at 10:07:02:
Suggest you check each component of the cooling system. That is the only way to find out the cause of this.
Does the radiator have full flow? Disconnect both inlet and outlet and run a garden hose through it both directions. There should NOT be any pressure drop in either direction. If there is, blocked somewhere in there.
Does the intank tranny cooler interfer with the flow? Is the tranny in good order or is it adding tons of BTUs and is what is causing the over temp?
Is the radiator cap in good order? Is it holding pressure? Is it of the right specs? Meaning is it long enough to close off the inner and outer sealing surfaces? It should be a closed system with an overflow bottle. No air should be inside the inner pressure system.
Is the air flow impeded in any way? Are the AC condensor fins bent and blocking? Is the air flow forced to go through the radiator or has some of the side shrouding been removed?
Everyone has talked about the rotation of the pump, fan clutch and fan. Make sure, double make sure. If V belt, rotation is CW looking at the rig from the front towards the rear. If serpentine belt rotation is CCW looking at the rig from the front towards the rear. The wrong rotation parts seem to fit and looks the same.
Does the water pump actually pump volume and pressure? Confirm that by taking off the upper hose and clamping a blocking plug in the hose. Turn on the engine and "feel" the hose. It should pressurize and become VERY hard.
If you have a bypass hose, make sure it is connected correctly and not going to wrong nipple. Can have coolant going in circles bypassing the radiator. Ditto the heater hoses.
Don't think your year has the double poppet thermostat and the bypass recirculation path. The thermostat shouild only have one valve, not two valves. Or if it does have a bypass poppet required and you don't have right thermostat, it can recirculate hot coolant back into the engine without sending it to the radiator. Just for kicks, consider brand new 180*F or 190*F thermostat (and that it's in the right direction..silly but have seen this happen).
Ditto rotation of the new fan blade and fan clutch. On my OEM fan blade and the severe duty fan clutch, it sounds like an airoplane when it engages. Can't imagine what it would sound like with your fan blade...and would be afraid it would take off into the radiator. SD fan clutch couples 80%-90% of water pump shaft rpms to the fan blade, while OEM fan clutch only couples 50%-60% of water pump shaft rpms. When this is working properly it should be like a hurrican in there!
Check that the hoses are in good order or new since you've rebuilt. Sometimes the intake hose from the bottom radiator will collapse when it's worn out (should have a spiral wire or some sort to keep it from collapsing during water pump draw).
Finally (and you don't want to hear this), the engine maybe just plain bad. Assembled wrong, or is blown...and/or tranny too.