258 l6 runs hot

[4x4cj5]

I just got a 1974 Jeep CJ5 for my 13th birthday (December last year) and I am fixing up the body (rust) as well as mild brake mods (want discs up front). My grandpa swapped the stock AMC 258 i6 / 4.2l w/ an '84 AMC 258 i6 / 4.2l .

Anyway, I drive it in the woods every now and then, almost always at around 25 mph (thick woods) and when idling, runs at about 230, give or take 10 or so. I was told that they were tuned to run lean from the factory, but it isn't the factory engine, as said above. I haven't yet tried to adjust the fuel/air mixture since I'm busy w/ the body. I want to fix the issue just to be safe, but my budget for this is AMC 150 bucks, since I don''t have a regular job and still need $$$ for a couple body panels. Any advice would be appreciated!

 

[SrBeaver]

Was the T-stat replaced with the swap? If not I'd start there. take the cap off then warm up the engine and check to make sure it's flowing. Fixed fan or clutch, if it's a clutch fan make sure it is engaging at operating temp, if it's not fully engaging it won't cool properly.

 

[BusaDave9]

Welcome to the site 4x4cj5
:ww:
When you drive slow you can't rely on the wind blowing through the radiator. The fan needs to be working good. As SrBeaver said the fan clutch may be bad. It might be hard to tell but when they are bad they turn too easily or they may be leaking a little. They have oil in them.
If the thermostat is bad the engine may run hot even when it's cool out or when on the highway.
If those things seem to be okay it could be a bad or clogged radiator.

 

[BusaDave9]

My grandpa swapped the stock AMC 258 i6 / 4.2l w/ an '84 AMC 258 i6 / 4.2l .

Make sure the water pump matches the belt configuration.
If you have v belts you need a standard rotation water pump.
If you have a serpentine belt you need a reverse rotation water pump.
The serpentine belt turns the pump the opposite way.

 

[73CJ]

Check you radiator fins. They can plug with mud. . .

 

[BusaDave9]

Check you radiator fins. They can plug with mud. . .

says the mudder from Minnesota.
I don't think they get much mud in Arizona.


EDIT:
Oops, my mistake. It's not Arizona.
I don't know how much mud they get in Jeep country.

 

[JR74CJ5]

EDIT:
Oops, my mistake. It's not Arizona.
I don't know how much mud they get in Jeep country.

:laugh:

 

[4x4cj5]

I should check the thermostat 'cause the fan clutch and radiator are fine. Thanks for the advice!