91 Comanche Overheats

jeepguy77 · Post by **jeepguy77** » Fri Jun 08, 2012 8:58 pm

Hey all my Dad's/brother's 91 Comanche has an overheating problem, we have replaced the radiator hoses, waterpump and thermostat. I have hear that these have problems with the radiators plugging up, but how common is this, we would really like to get this thing back on the road its the truck I learned to drive in, and its soon to be my little brothers truck. It needs a bit of work but this is the main thing.

Thanks,

Post by **Stuka** » Fri Jun 08, 2012 9:15 pm

As I recall, '91 moved back to an open loop system correct? (Radiator cap on radiator rather than on bottle next to fire wall)

If its still a closed loop system, these can be quite difficult to get all the air out.

If its the open loop, I doubt air bubbles are the issue. Its possible it is the radiator is plugged. Its also possible the fan is no longer turning on when it should, or is running slower than it should. Have you verified it kicks on when it should?

jeepguy77 · Post by **jeepguy77** » Fri Jun 08, 2012 9:27 pm

This one has a radiator cap, it also only has a mechanical fan. the antifreeze does look fairly clean, and there are no signs of a blown headgasket.
We also have flushed the radiator twice thus far.

the specs on this truck are, 4.0/ax15/np231/d30/d35

Post by **Stuka** » Fri Jun 08, 2012 9:32 pm

jeepguy77 wrote:This one has a radiator cap, it also only has a mechanical fan. the antifreeze does look fairly clean, and there are no signs of a blown headgasket.
We also have flushed the radiator twice thus far.

the specs on this truck are, 4.0/ax15/np231/d30/d35

Does the fan have a clutch? if so, how does it feel? If the clutch is worn, the fan isnt going to pull any air.

jeepguy77 · Post by **jeepguy77** » Fri Jun 08, 2012 9:35 pm

the clutch feels pretty good, its not loose or anything. It does run a little cooler with the heater going on full blast.

Post by **Stuka** » Fri Jun 08, 2012 9:44 pm

jeepguy77 wrote:the clutch feels pretty good, its not loose or anything. It does run a little cooler with the heater going on full blast.

Then its sounding like its the radiator. Now you can try some radiator flush. It may help. Or you may need to have the radiator cleaned by a radiator shop.

jeepguy77 · Post by **jeepguy77** » Fri Jun 08, 2012 10:02 pm

Yeah I was afraid he radiator maybe clogged. we may try the radiator flushed by a shop. Or do you know of any better radiator flush solutions besides the prestone brand?

Post by **Stuka** » Fri Jun 08, 2012 10:07 pm

The prestone one is the only one I have ever used.

jeepguy77 · Post by **jeepguy77** » Fri Jun 08, 2012 10:43 pm

Ok I was just wondering since we tried that twice already so maybe we will make a call to the radiator shop and talk to them about cleaning it.

carnuck · Post by **carnuck** » Sat Jun 09, 2012 2:30 pm

Sounds like time to replace the rad. That is assuming the stat has been changed?

jeepguy77 · Post by **jeepguy77** » Sat Jun 09, 2012 2:43 pm

Yeah we have replaced the t stat, and water pump

AustinAubinoe · Post by **AustinAubinoe** » Sat Jun 09, 2012 3:55 pm

If its an all brass radiator, you can use this stuff:

http://www.permatex.com/products/Automo ... leaner.htm

Going to use it on my wagoneer before I do the water pump and hoses. I got it from rockauto.

If you need a new radiator I highly recommend this one! Dang it was $190 when I bought it,

http://dpgoffroad.com/products/csf-hd-r ... r-97-06-2/

jeepguy77 · Post by **jeepguy77** » Sun Jun 10, 2012 6:35 pm

Cool I may have to try that permatex stuff.

Full Size Jeep Network