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Temp gauge creeps up, 88 wagoneer xj

Could have air pockets in your cooling system.

What was the reason for changing the sender?
 
fairly green at diagnosing problems, thought i would start cheap. logic said that if it was saying it was hot but not really hot, there may be an issue with the unit reading temp.

forgot to add in first post, it will read about 260 after letting it idle for a little while but if i hit the throttle to about 3500 the gauge will drop rapidly..
 
Could be air pockets, Renix closed systems are notorious for it.

I would be suspicious of the fan clutch. Do you have an efan?

Anyway, warm the engine up fully, shut it off, and then try to spin the fan. If it spins easily, the clutch is shot. I always recommend upgrading to the ZJ HD fan clutch, NAPA part number 272310, $44, direct fit replacement.

You can check for air trapped in the system by parking nose-down, then remove the temperature gauge sender at the rear of the head to see if any air comes out, or add coolant to the pressure bottle until it flows from the sender's hole. Things will be hot so be darn careful, or do it with the engine cold. Next time you change a thermostat drill a couple holes in the flange part, 1/8" or so, far enough in from the outside edge so the housing and head mounting surfaces won't block them, then position the thermostat with a hole at 6 and 12 o'clock.
 
fairly green at diagnosing problems, thought i would start cheap. logic said that if it was saying it was hot but not really hot, there may be an issue with the unit reading temp.

forgot to add in first post, it will read about 260 after letting it idle for a little while but if i hit the throttle to about 3500 the gauge will drop rapidly..

air in the system and its not circulating until high revs or the radiator is blocked up. my 89 did this until i swapped out the radiator with a 3-row, but most likely just air in your system.

do a search for closed cooling system and burping. closed system works well only when ALL parts are in good shape/condition and you understand the system.
 
Could be air pockets, Renix closed systems are notorious for it.

I would be suspicious of the fan clutch. Do you have an efan?

Anyway, warm the engine up fully, shut it off, and then try to spin the fan. If it spins easily, the clutch is shot. I always recommend upgrading to the ZJ HD fan clutch, NAPA part number 272310, $44, direct fit replacement.

You can check for air trapped in the system by parking nose-down, then remove the temperature gauge sender at the rear of the head to see if any air comes out, or add coolant to the pressure bottle until it flows from the sender's hole. Things will be hot so be darn careful, or do it with the engine cold. Next time you change a thermostat drill a couple holes in the flange part, 1/8" or so, far enough in from the outside edge so the housing and head mounting surfaces won't block them, then position the thermostat with a hole at 6 and 12 o'clock.


efan is set to run continuously due to a previous owner and problem he had.

what is "easily"? i can physically turn it 360 repeatedly..

will try holes in thermostat
 
When warmed up and engaged you shouldn't get more than 45-60 degrees of movement of the fan--it should be stiff.
 
Have you used a temp gauge to check actual temp? Does your efan actually work/turn on when it gets hot? Otherwise joe knows whats going on.
 
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