Overheating 87 TBI

[rys272]

How hot does it actually get? Put a real gauge on it, and see what happens. You may be pleasantly surprised.

When does it overheat? Idle? Going down the road?

Are all the factory rubber baffles/gaskets/seals around the radiator in place? Any air that goes around the radiator instead of through it is wasted airflow. People toss those thinking they aren’t important, GM wouldn’t have put them there if they weren’t needed.

Does the truck run as expected? How is the tune?

Gets hot to the point where it shoots out of my radcap all over my driveway? overheats no matter what idle, in gear, going slow, going fast.

Haven’t been able to get her up to temp and really test her today after drilling two 1/16th holes because I’ve also been working on this misfiring issue but do believe that has done the trick will post again if it starts overheating again, probably going to change fan clutch regardless of this working.

 

[rys272]

Seems the bypass is plugged or something along the lines. Got a new thermostat drilled two 1/16th holes and works awesome doesn’t overheat doesn’t quite get up to temp as I’d like but a lot better than before and it’s still pretty cold here so imagine won’t be a problem in the summer if not I’ll just buy a new one and go with 1 1/16th hole. Still going to replace that fan clutch and pull freeze plugs etc.

 

[edgephoto]

You should give your system a nice flush. Get some Citric Acid powder. Mix 1lb to 5 qts of warm water. I would mix up 2lbs worth.

1. Drain cooling system
2 Remove thermostat
3. Fill cooling system with the citric acid mixture
4. run engine for at least 15mins. 1 hour is best.
5. drain the cooling system
6. using a flush tee in the heater hose flush with clean water until water is coming out clean
7. install thermostat
8. fill with proper mix of coolant

Either buy a thermostat with a jiggle pin or drill a 1/16"-1/8" hole. This will help get the air out. Also using a vacuum filler really works well.

Mercedes and VW sell citric acid over the parts counters as a cooling system cleaner.

 

[Ricko1966]

Seems the bypass is plugged or something along the lines. Got a new thermostat drilled two 1/16th holes and works awesome doesn’t overheat doesn’t quite get up to temp as I’d like but a lot better than before and it’s still pretty cold here so imagine won’t be a problem in the summer if not I’ll just buy a new one and go with 1 1/16th hole. Still going to replace that fan clutch and pull freeze plugs etc.

Many people plug the bypass on purpose,some water pumps aren't drilled for a bypass. If you buy one of those waterpumps they tell you to run a drilled thermostat. I wouldn't mess with the fan clutch unless you are still having overheating problems,run the drilled Tstat awhile that maybe all you needed.

 

[SquareRoot]

I got an idea.