99 5.2l

194000

Truck keeps overheating.

The following have been done

1. Full coolant flush, yes, the air is out

2. 10000 miles ago thermostat was replaced. You can feel the upper hose and tell when it opens, that should be good.

3. I have the ffdynamic radiator fan setup. Works great no issue, just installed it

4. Radiator cap is in the way

5.Water pump replaced new

Is it at all posable the radiator is bad? Had a pressure test and it passed.

 

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3. Is the fan sealed against the radiator so no air can come in around the sides? If not the fan may be drawing more air through the sides than through the radiator. For that matter, if it's a shrouded fan and the fan opening isn't about 80 percent of the radiator's size, the fan opening is restricting airflow through the radiator. If it's right against the radiator, same thing. If it's using a shroud that blocks off part of the rad it really needs to be an inch or two back, and the perimeter needs to be sealed against the radiator. A rubber gasket fastened to the shroud is best, a slit fuel line hose works well enough, foam can be sucked out by the fan.

I'll also add that the last time I had a fan stuck directly to the radiator, the blade worked its way loose from the motor housing. It started wobbling, then ground a hole in the radiator before the blade self-destructed. I've not used a fan that attaches to the radiator via nylon straps since.

4. Had a buddy with a Mustang that kept overheating, he'd replaced the entire cooling system trying to solve it. Turned out to be a bad rad cap. As a result, I've started troubleshooting overheating problems by replacing the cap after first ensuring debris hasn't blocked the radiator off because it's super cheap and takes 2 minutes. If it doesn't work, I now have a spare cap and no harm done.

5. In the Chevy world, first gen small blocks had water pumps that went clockwise or counterclockwise depending on whether it was a V-belt or a serpentine belt engine. Problem was, aside from the impeller they were identical. No idea if Dodge ever made that particular engineering mistake (should have had a larger pulley bolt pattern on the serpentine pumps so the pulleys wouldn't interchange) or not but it would be worth checking. Quickest way to tell on those Chevy engines, pull the thermostat housing off and start the engine. If it gushed out the engine it was correct, if out the hose the water pump was spinning backwards.

6. To check the radiator, start it and let it reach operating temp, then shut off the engine and feel around back of the radiator. If the radiator is plugged, that part will be a lot cooler than the unplugged parts. Changed a radiator on an S10 Blazer once with a Crapzone special, and the whole bottom half of the new radiator was plugged up. The top half was so hot you couldn't touch it, the bottom half was cold. A plugged radiator will pass a pressure test because a pressure test only checks for leaks, not capacity.

When exactly does it overheat anyway? Only when idling, only when the AC is on, only low speeds, only high speeds, only when the outside temp is over a certain temp, all the time?

 

Was it overheating before you put the fan in?

 

What are the hose temperatures for top and bottom hose?

Has the heater core been backflushed?

Does the thermostat have a 1/8" or larger bleed hole drilled in it?

Is water pump a FlowKooler or a box store brand?

When do you have the radiator fan set to come on?

Is the thermostat a 180, 190, or 210?

 

Quote:

Originally Posted by Vimes

1.
When exactly does it overheat anyway? Only when idling, only when the AC is on, only low speeds, only high speeds, only when the outside temp is over a certain temp, all the time?

I agree.... This has to be answered before much specific help can be given.

 

issue fixed it was the thermostat