4.0 still overheats after new parts

sterfry2004 · 09-19-2009, 03:58 PM

My 97 Cherokee Sport overheats after idling between 2 and 3 RPM for several minutes. It gets to 210 at a normal rate, then eases up to the next line and maintains that temp for a while. Even at that temp, the engine will start to steam/smoke and wreak of coolant. Coolant is not leaking anywhere.

Things I've done:
1) Radiator was new as of August '08.
2) Water pump just replaced.
3) Thermostat (190 degree) just replaced.

Other (related?) problems:
1) Bad Compression on cylinders 2 and 4. I didn't test this, but was told by my mechanic. He said the culprit was warped piston rings due to the overheating.

Coolant seems to be flowing properly through the upper and lower radiator hoses. Oil still looks good on the dipstick. All of the hoses seem to be in good condition; no leaks or anything.

What's my next step? Will fixing the compression issues fix the overheating issues also, or are they most likely separate?

RCHavok797 · 09-19-2009, 04:25 PM

Why is it idling between 2 and 3 thousand rpms?

sterfry2004 · 09-19-2009, 04:57 PM

I should have specified. I keep it revved that high because it will stall if allowed to idle at its normal idle speed.

**Cdn96XJ** · 09-19-2009, 05:16 PM

Bad head gasket could be a possibility. Coolant is getting into your cylinder walls and burning up. You said coolant is not leaking anywhere however do you need to top it up every once in a while?

sterfry2004 · 09-19-2009, 06:14 PM

Well, the jeep has been out of commission since January '09 due to the overheating issue. I'm just now getting the time and funds to start working on it. Prior to the initial overheating in January, though, I don't recall having to add coolant to it, and it didn't have any overheating issues.

**xjfever** · 09-19-2009, 06:29 PM

Overheating at idle or at low speeds in traffic is a sign of low airflow. I would replace the fanclutch and make sure the electric fan is working correctly.

duntov · 09-19-2009, 06:33 PM

Pressure check your radiator...mine had a small leak in the radiator and it wreaked antifreeze but I couldn't see it leaking out anywhere. I replaced the radiator and cap and it worked like a champ.

sterfry2004 · 09-19-2009, 09:22 PM

Both fans are operational. Does that mean they're fine, or could they both spin and be faulty?

Is a pressure check something I could do myself, or does the jeep need to be taken somewhere like Autozone? What tools would I need?

Thanks for all your input!

sterfry2004 · 09-19-2009, 09:32 PM

Both fans are operational. Does that mean they're fine, or could they both spin and be faulty?

Is a pressure check something I could do myself, or does the jeep need to be taken somewhere like Autozone? What tools would I need?

Thanks for all your input!

**xjfever** · 09-19-2009, 09:43 PM

The fan will still spin if the clutch is bad, it just doesn't spin fast enough to cool the coolant in the radiator. Have you been able to drive the jeep? And if so does it overheat at road speeds?

**DannyRoark89** · 09-19-2009, 09:47 PM

pull your thermostat and see if that helps, you can get bad ones that are new, you can check it by puttin it in boiling water and seeing if it opens, also check your overflow hose, if its clogged there is no place for the steam to escape to, it happened to me and caused a giant mess and an expensive one for a 3 dollar hose

sterfry2004 · 09-19-2009, 11:51 PM

Right now I have the rear diff taken apart, but I feel like it would overheat. Before I replaced the therm and pump, it let me drive normal speeds for about 15 miles before overheating. Doesn't seem like the pump was the real issue.

The thermostat is definitely opening, and the overflow hose was replaced two days ago due to a split.

newxj · 09-20-2009, 12:52 AM

Quote:

Originally Posted by sterfry2004

...and the overflow hose was replaced two days ago due to a split.

And you still feel it will overheat? I suggest putting the rear diff. back together and road test it.

**xjfever** · 09-20-2009, 06:52 AM

I would pressure test the system to check for leaks/head gasket.

wills88xj · 09-20-2009, 07:10 AM

i dont remember what years it was but some of the 4.0's had a problem with air getting traped in the head after complete draining .the way to fix this is to get the front of the jeep at as much of a angle (the closer to 45 deg the better ) then top off coolant and let it run for a while . it will burp its self .

the way to tell if your fan clutch is working is .when its cold it should have very little resistance ( spin pretty easy) with the engine off!!!!

after it warms up turn the engine off ,it should be harder to spin
it is thermostaticly controled