Truck runs better hot

[86suburbanNJ609]

I noticed the truck response is alot better when it's running at 190 while on the highway it drops to 165 and just seems less responsive shifting and throttle response. My question is has anyone else noticed the same thing? Also should I put a thermostat in it that runs hotter or leave it be? Temps around here are still around 40 only a matter of time before gets hot here in Jersey

 

[Blue Ox]

Temp should stay consistent once it's warmed up. Something's up. Stuck thermostat, or incorrect type?

 

[86suburbanNJ609]

At idle it's 190 195 while cruising on highway it reads 165
That's a thermostat problem?

 

[Blue Ox]

Possibly. That's a thermostat's job. Restricts coolant flow when the engine is cold and regulates flow to maintain temp when it's warmed up. They aren't perfect, but a 30° swing is a lot.

Does the truck take a long time to warm up? It may not be closing sufficiently to maintain temp.

 

[86suburbanNJ609]

No not long at all 5 minutes tops

 

[Blue Ox]

Still probably the first place I'd look is the t-stat. What is the vehicle history? Has it always been like this or is it a new problem?

 

[Craig 85]

My last truck was a '79 K15 with a 350. The PO had installed a stock replacement aluminum radiator. I ran a 195 thermostat due to California emissions. It consistently ran below this during the winter and cooler months. The only time I could get it close was in the summer in city traffic with the A/C on.

 

[86suburbanNJ609]

Been like that since I brought it home. It doesn't run bad by no means but I just noticed when it's at the idle temp of 190 it's snappier.

 

[Blue Ox]

30° still seems like a lot. How's the fan clutch working?

 

[82sbshortbed]

30° still seems like a lot. How's the fan clutch working?

I agree ^

Seems like fan clutch is worn and not engaged enough at idle. Do you have a fan shroud? It's always gonna run hotter at idle but 30 degrees is pretty big jump. 195 is still not too hot. My 2000 camaro ss runs about 185 at idle or driving down the road.

 

[86suburbanNJ609]

No shroud on it right now just got brackets at scrap yard wrong ones. Apparently the PO put a different radiator in it not anything close to factory nothing lines up.

 

[1987 GMC Jimmy]

If it’s in your budget, I’d do the correct radiator. Trying to make rad hoses, rad cap, shroud, cooler lines, and the fan not bang into each other or other parts is worth it for the cost of a new one.

 

[Rusty Nail]

Wait a minute. You have the wrong radiator, no shroud, and you question a $5 thermostat over thirty degrees cooler operating temps sometimes?

 

[RoryH19]

I have the factory rad, shroud, and 190 degree stat the truck calls for.
It's TBI and will complain if you run a lower degree stat. They are sensitive.
I also have a wide range on temp maybe not 30 but at least 20 degrees. The stat is new, the water pump is new, and also the clutch. I even have new upper and lower houses.

As suggested above I would try and put the factory parts back on the truck before you start chasing problems that may be solved by proper air flow.

 

[Billy]

The tbi is designed to run at 200°. Bring on the vitriol