Overheating Sob Story

[FrankHKP7]

Hey guys...

Been a lurker here for some time. The forum has always been a great resource for DYI repair of my XJ's. Thank you for the all the help in the past.

I've read every one of the hundreds of pages that have the word overheat!

Specifics:

2000 XJ 4.0 - 98k

2010 - Overheating issues:

Replaced Water Pump, Thermostat, Heater Core, Evaporator, Radiator too late to save the head. Truck ran great (couple months) until the head gasket completely went. Parked truck in my garage for 10 months until I had time to pull it apart and replace the head gasket/ head.


Last week:

Replaced 0331 head w/ remanufactured 0331 head. Truck runs perfect for about a half hour and then overheats. Pulled Autozone thermostat, replaced with a Stant, Replaced Rad Cap w/ Stant 16 pounder. The sensor on the thermostat housing reads dead nuts against an IR thermometer and my OBD live reader. Burped the system, started the truck up, filled with more coolant until it wouldn't take any more. Ran it up to 210 on the gauge, shut her down, cooled her off, added more coolant. The typical routine...

Still overheated.

Let her cool off, drained the system down, ran water through every hose and all drained from the lower rad hose bib. Nothing is clogged as far as I can tell. Filled her up w/ plain water... went through the process again... Still overheats after a half hour.

The efan kicks on at 216. Truck hits 255 and check gauge light comes on and it pegs at the 255 mark on the temp gauge.

The oil is fine, no milkshake, there is no exhaust smell in the antifreeze.

At a complete loss here. My next thought is to pull the thermostat all together and see if the truck still overheats.

Any ideas guys?

Thanks!

Frank

 

[Bjorn86]

What kind of condition is your fan clutch in?

 

[FrankHKP7]

What kind of condition is your fan clutch in?

I knew someone was going to ask that...

It's the original fan clutch. Is there a fool proof way of testing it? I would like to test it before i go out and buy a new one.

Also I forgot to mention I don't have the fan shroud around the the fan. Could this be part of the cause of the problem?

Thanks,

Frank

 

[Bjorn86]

I'm not sure on how to test it, I would just replace it. I'm sure there is info on here about how to test it. Also, from what I've read, the fan shroud does make a difference in cooling efficiency. I just ordered a new fan shroud for like $9 on partsgeek.com 2 days ago. If it were me, and I had gone through all the trouble you had, I would go out and get those two parts.

 

[FrankHKP7]

I'm not sure on how to test it, I would just replace it. I'm sure there is info on here about how to test it. Also, from what I've read, the fan shroud does make a difference in cooling efficiency. I just ordered a new fan shroud for like $9 on partsgeek.com 2 days ago. If it were me, and I had gone through all the trouble you had, I would go out and get those two parts.

I have the shroud, just forgot to put it back on.

I understand not having the shroud can rob cooling efficiency, but can it effect the cooling system THAT much without it?

I'll pick up a new fan clutch tomorrow after work.

 

[chasdb]

How's your fan clutch and belt tension?

Whats your temp drop thru the radiator?

Fan shroud intact, good airflow thru the radiator?

What radiator did you install?

How did your head gasket fail, coolant >external leak or to a cyl, coolant > oil?

Are you consuming coolant?

 

[FrankHKP7]

How's your fan clutch and belt tension?

Belt tension is good, using a cricket gauge. Fan clutch is original. Will replace tomorrow.

Whats your temp drop thru the radiator?

Will test that tomorrow w/ the IR gun.

Fan shroud intact, good airflow thru the radiator?

I need to reinstall the fan shroud. Will do this tomorrow after I replace the fan clutch

What radiator did you install?

Nothing fancy, two core job from advanced auto.

How did your head gasket fail, coolant >external leak or to a cyl, coolant > oil?

Cracked head. between #3 and #4 cylinder. 0331.

Are you consuming coolant?

Not as far as I can tell.

 

[Tim_MN]

Buy a new fan clutch, and install the fan shroud.

Use 50/50 antifreeze and water, not plain water. Fill the radiator until full. Start the engine and add more coolant as the level drops. When you get a small gush of coolant as the thermostat opens, install the radiator cap. Fill the reservoir and monitor it level every day for about a week of daily use.

 

[ParadiseXJ]

Go out while the Jeep is cold. Give the fan a spin. Should spin fairly freely...not round and round...just freely.

Start the Jeep, get it up to temp. Turn it off. Now go spin the fan again with the engine hot AND off.

Should NOT spin freely...if it spins freely, replace the fan clutch.

...and put that fan shroud back on. Besides cutting a finger off it MIGHT make that much of a difference.

 

[FrankHKP7]

Go out while the Jeep is cold. Give the fan a spin. Should spin fairly freely...not round and round...just freely.

Start the Jeep, get it up to temp. Turn it off. Now go spin the fan again with the engine hot AND off.

Should NOT spin freely...if it spins freely, replace the fan clutch.

...and put that fan shroud back on. Besides cutting a finger off it MIGHT make that much of a difference.

Thanks! I'll go try that now! I agree about cutting a finger off... It HAS crossed my mind.

 

[GrimmJeeper]

there should be slight drag on the fan when cold, and none at all when hot. if it spins more than the length of two blades when its cold its junk, if it moves more than one once you let go of it hot its also junk. when hot it should stop the second you take your hand off of it.

I agree with the fan clutch diagnosis, that's where I would put my money.

 

[Pelican]

You are going to replace your shroud so no point in beating it to death but consider that without the shroud, the air the fan pulls comes from anywhere and everywhere via the path of least resistance which is not through the A/C condenser and radiator.

 

[heisenberg]

there should be slight drag on the fan when cold, and none at all when hot. if it spins more than the length of two blades when its cold its junk, if it moves more than one once you let go of it hot its also junk. when hot it should stop the second you take your hand off of it.

I agree with the fan clutch diagnosis, that's where I would put my money.

My fan clutch is just as you described when hot, but spins very freely when cold. Please explain how the tension matters if the engines cold?

 

[GrimmJeeper]

cold doesn't matter as much but usually when they freewheel cold it indicates that it is wearing out.

 

[Tim_MN]

A 12 year old fan clutch is probably marginal, spend the $35 and buy a new fan clutch. :doh:

 

[souske]

Get the Zj 4.0 clutch, not the max cool, just regular zj one

 

[FrankHKP7]

UPDATE- Bought the clutch.

Decided to put the shroud back on before I pulled the clutch.

Thing ran like a top. Gauge didn't go over 220 after idling for an hour w/ ac on, off, heat on off, lights on and off...

I didn't have a chance to run it around town tonight but will report back tomorrow after I run it around awhile.

 

[Bjorn86]

So are you running at 220 with the new fan clutch and shroud, or are you still running the old fan clutch w/shroud in place?

 

[FrankHKP7]

So are you running at 220 with the new fan clutch and shroud, or are you still running the old fan clutch w/shroud in place?

The old stuff. I had the truck parked.

 

[Foothill]

Souske - why is ZJ clutch better?
Frank - could be both the shroud and clutch contributing. Hope you put in new clutch and report back the results. Good luck