Overheating problem only when off-road.

FSJ10

New Member
Joined
Jun 25, 2009
Location
Asheville, NC
My 1983 J10 has the 360, all new radiator and hoses, new thermostat, and transmission fluid cooler installed. The tranny filter has been changed recently. All fluid levels are good in the motor and all tranny components. The truck runs at 190 degrees temp all day long on the hiway. she's been timed up and runs great. She has the stock dana 44 locking hubs up front and the stock AMC 20 in the rear. The 4 wheel drive system pulls strong.

BUT after just a mile of moderate trail off-roading in 4-wheel drive, she'll start to get hot (210-220) and after just a couple more miles, under basically no stress at all, she'll peg the 250 degrees on my gauge. What is going on?? Any ideas would be helpful. Thanks!
 
radiator undersized? My CJ would run real hot, I finally put the fan thru the rad., forcing me to replace it. My replacement was a 3 row, compared to the old 2-row...cooling problems disappeared.
 
It sounds like a typical symptom of a faulty fan clutch. Going down the road at highway speed you're getting plenty of air to keep things cool. Crawling down a trail doesn't move enough air to provide adequate cooling. If it's got a fan clutch, I would look there first.
 
cooling is always tricky.
Could be
Clutch fan
lack of fan shroud
water pump weak
Tranny heating up, so heating up engine
radiator inadequate, or stopped up

I would change out the clutch fan, add a tranny cooler, and add a simple switched aux fan on the front.
Also to help with such things, I have always run an extra qt of oil in the engine, helps with cooling and keeps oil moving on steep inclines.
If these things don't work then you may want to go with a radiator boil and rod, maybe a solid fan, and maybe even a new radiator.

sucks trying to diagnose this stuff I know, but everything you do will be an upgrade
good luck
 
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