Hi All, I recently bought a CJ 7 with an inline 6 engine and I am having cooling problems. I've already changed the thermostate and waterpump, and replaced the fan with a slightly larger flex fan. Coolant does seem to be flowing through the radiator, however, neither the hose coming off the block into the heater core nor the hose coming out of the heater core to the water pump are getting any where near as hot as the top radiator hose. My temp gauge gets well past hot within 10 min just sitting at an idle. I'm not sure what else to check and would appreciate any information you guys can provide.
2. Heater core replacement. You could temporarily bypass this by rerouting your hoses, then see if your engine still gets hot. If it does - your radiator needs to be recored. If it doesn't, the problem mostly is a result of poor circulation through your heater core.
To me, it sounds like it's both, but do some research on the points above.
Stop throwing money away and guessing. Changing the fan won't fix the problem. At best it's only going to treat the symptoms.
You need to establish whether or not you're getting circulation through both the block and the radiator. Rodding your existing radiator will most likely give you better results than replacing it with a new aluminum one. But it won't do anything if water can't circulate through the block. You might also want to verify that the bottom radiator hose is still in good shape. When they start to go bad they will collapse when running and stop the circulation. Most guys prefer a hose with a spring in it to prevent collapsing. Hose manufacturers say the new hoses won't do that though, even without a spring.
If your Jeep is typical, it had the four bladed fan with no fan clutch. That set up works perfectly fine to cool your engine. Even here in Arizona it doesn't overheat if it's working like it's supposed to. The 258 is a very simple machine and there's no reason to make it more complicated than it is.
That engine also tends to run warm. It's supposed to have a 195° thermostat in it. As others have mentioned, don't trust the TEMP gauge, verify it another way.
I'd rather be lost on the trails than found at home!
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Do you have a fan shroud? You really need one.
Get rid of the 'flex-fan' and find a 7 blade OEM.
Are you sure you have the WP with the correct rotation. 2 WP's are made, one for v-belt and one for serpentine belt(reverse rotation).
Rod out or recore your radiator to at least a 3 row.
Run a 16-18 lb cap.
Do you have a 'bug-screen' on your grill? Get rid of it!
Confirm your not run'n a lean fuel mix(vacuum leaks)by 'reading' your s'plugs.
Have'n you along, is like loose'n 2 good men
cheap easy test of radiator,
take loose upper and lower radiator hoses from radiator, also take off radiator cap.
hold your hand over the lower radiator opening
have a buddy fill radiator with water.
when radiator is full remove your hand from the lower outlet and watch the water as it exits the radiator, if the radiator is open and clean, the water should shoot out of the lower radiator outlet, good steady flow.
if radiator is partially stopped up the water will slowly exit the radiator and gurgle along as it runs out.
you need a fast flow
this is a cheap way to check radiator,
if stopped up, have it rodded out, before you ruin that good motor, as overheating is the second fastest way to ruin a good motor, lose of oil pressure is the fastest way to ruin a good motor.