Temperature Gauge Spike/Overheat

[XJ Eric]

I'm hoping not. I've been looking for white smoke and took a whif near the tail pipe and I'm not getting any coolant smell out of the pipe. My freeze plug has been leaking for years. I drove it this morning for a mile out and back at 40-50 mph. It got a little warm (one tick over 210) but It went over and spiked when I turned the A/C on. I'm going to try turning the heater on to see if that brings it down. If it does then, I'm pretty sure its the stat. If it's the head then the heater being on shouldn't be able to reduce the temp by much. (since it's boiling) I'm at around 180,000 miles so it's time to replace something.

I'm not getting any of the classic cracked head signs. Cappachino colored oil/coolant, power loss, missfires. haven't checked compression yet, but I'm pretty sure low compression would cause a code for something.

 

[Tim_MN]

Here is list of thing to do to fix your overheating, which ones seem to confuse you ?

-Use a flushing/cleaning solution and then drain and fill the radiator with a fresh 50/50 coolant and water mix. With a neglected cooling system you may have to flush several times.
-Inspect the radiator for mud/bugs/grass clogging the outside and mineral deposits clogging the inside. Clean or replace as needed.
-Replace the thermostat with a STANT or Robertshaw 195* thermostat. Cheap thermostats are cheap for a reason.
-Replace the radiator cap . An old worn out cap will allow boil overs and/or allow the coolant flash over into to steam. You will see the coolant temps suddenly jump from 210* to the Red Zone and back to 210* if your radiator cap is weak. ( any other worn parts that allow the coolings sytem pressure to drop will have the same symptoms )
-Inspect/test or replace the mechanical fan clutch. A worn fan clutch will allow temperature creep at stoplights, in heavy traffic, and on the 4x4 trails. A fan clutch that “looks” OK is not the same as working OK. Consider installing a Heavy Duty fan clutch such as the NAPA #272310.
-Inspect the electric cooling fan and the fan relay. Apply 12 volts and make sure the fan runs. Exchange the cooling fan relay with one of the others similar relays. Confirm that the e-fan starts when engine temps reach 215-218*. Repair or replace the fan or relay as needed.
-Inspect/test or replace the coolant temperature sensor that activates the e-fan.
-Replace the water pump. The pumping fins can deteriorate over time and the pump will not flow enough coolant to keep the temps under control.
-Inspect/replace the radiator hoses. Make sure the coiled wire is installed in the lower hose.

If you have covered all the points listed above and still have overheating issues, inspect the head for cracks and head gasket for leaks. Exhaust gasses entering the coolant can raise the temperature of the coolant or cause steam pockets in the coolant that will temporarily block the flow of coolant.

Read more about cooling systems here –

www.offroaders.com/tech/engine-overheating.htm

www.familycar.com/classroom/coolingsystem.htm

 

[blubullett]

I had a cracked head for a year with no white smoke, odor, or milky oil. And turning on my heater would always cool it down to normal. Go to autozone and get the coolant tester. It is easy and only takes a couple minutes to do. Do what needs to be done to fix the problem and stop hoping your problems will go away if you ask enough questions on here.

 

[Root Moose]

So, the head on the big Jeep cracked today.

#@$*!

Now I have two broken Jeeps in my laneway that look fabulous just sitting there but I can't drive...

I've been researching replacement heads over the last month or so.

Is Alabama Cylinder Head the best option? Beefed up so it doesn't crack, fully dressed, ready install for ~$510 each. Maybe they'll cut me a deal if I order two at the same time. Other supplier?

While I have the head off I figure I might as well replace the camshaft on the big Jeep with something that will help spin larger tires and tow the tent trailer. Recommendations on something that is OEM ECM friendly?

TIA

 

[birchlakeXJ]

Is Alabama Cylinder Head the best option? Beefed up so it doesn't crack, fully dressed, ready install for ~$510 each. Maybe they'll cut me a deal if I order two at the same time. Other supplier?

Alabama Cylinder Head is a good vendor. Another good source is Clearwater Cylinder Head.

Both offer a redesigned head that is a good replacement for the 0331.

Price and warranty varies a little bit; compare those things on their website. On one of those sites, you won't see the "Jeep" logo, you need to select "Chrysler" to get to the 4.0 heads.

 

[Root Moose]

Replaced the head and the viscous fan and one of the electrics that was grinding its bearings at the same time. Now the Jeep stays cool.

Interesting note about the Alabama Cylinder Head cylinder head, it must be their own custom casting because it does not have the TPY letters between cyls 3 and 4. ACH cast their own heads? Nutty.

 

[birchlakeXJ]

Replaced the head and the viscous fan and one of the electrics that was grinding its bearings at the same time. Now the Jeep stays cool.

Interesting note about the Alabama Cylinder Head cylinder head, it must be their own custom casting because it does not have the TPY letters between cyls 3 and 4. ACH cast their own heads? Nutty.

Glad you got it resolved. The only heads that you will see the letters TUPY on are the actual 0331 heads from Jeep (2003 and newer I believe)

 

[O-Gauge Steamer]

Alabama Cylinder Head, DBA Patriot Performance introduced the aluminium head for the 4.0. Hesco was buying them and reselling at a mark-up. Hesco now owns the rights to the head and it is only available from them for a tidy $1995.00. I paid a lot less back in 2005 to Patriot...

For those considering the head. It does work as advertised. The floor has been redesigned to allow better flow to the bowl which, by reducing turbulance, inceases the velocity of the charge. This gives a far quicker fill rate on the intake stroke. The exhaust ports/runners have also been designed with flow in mind. The valve cover mounting point is 0.500" taller than stock. This allows roller rockers to fit without having to resort to a spacer and its attendant oil leaks.

On my list to do again...

 

[Root Moose]

Glad you got it resolved. The only heads that you will see the letters TUPY on are the actual 0331 heads from Jeep (2003 and newer I believe)

Good to know.

Maybe I misunderstood what I read here and elsewhere (Jeep Strokers) but I was expecting the head to have the TUPY letters on them. It's a new casting, not reman, so I threw it on. Looked pretty darn good actually.

 

[Root Moose]

Figured I'd close out this thread.

Big Jeep has had the head replaced. Been driving it back and forth to work (~100 miles round trip) for a few weeks in some pretty stinkin' hot weather (95 - 105 deg F with stupidity, I mean humidity).

The temp gauge never moves. Perfect.

 

[ccain529]

I know this is an ancient thread but I stumbled upon it while surfing for a solution. My wife's '05 TJ is doing the EXACT same thing.

So far I've replaced everything (coolant flush, thermostat, cap, temp sensor...)
I tested the coolant for exhaust gasses but the test was negative. Hmmm.

Oh well, I guess it's off with the head. It wouldn't hurt to run it passed the machine shop to have it magnafluxed either way.

Anyway, I just wanted to say thanks for all the info in this thread. I was about to give up... I thought I was losing my grip there for a while.