1987 suburban tbi 350 overheating.

[shotrod69]

Take hood off and sit on motor. lol

Just get a heat gun and compare to temp gauge. They cost around $20.

Read front of block and intake manifold, temps are reading fine.

Do you think it could be the impeller slipping on the water pump?

 

[fast 99]

Doubtful, in 30 years of repair work only seen a handful of bad impellers. Those were in heavily rusted systems, impellers were rotted away. However, never want to say never when it comes to vehicles.

How do the temps compare to the cluster reading?

 

[shotrod69]

Doubtful, in 30 years of repair work only seen a handful of bad impellers. Those were in heavily rusted systems, impellers were rotted away. However, never want to say never when it comes to vehicles.

How do the temps compare to the cluster reading?

They read pretty much spot on. But it doesn’t seem to have the issue when I’m idling.

I’ve been working on semis for the past 6 years, if I had a nickel for every part that was bad out of the box or went bad 6 months down the line. I’d just put my truck in a shop.