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  #16  
Old June 14th, 2019, 18:14
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blu3fan blu3fan is offline
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Re: It's been discussed a millions time so what's a million and 1 more

before the trolls arrive.
last summer I was averaging 220ish anytime I stopped moving.
I replaced the fan clutch
got an upgraded water pump.
replaced the rad.
replaced the electric fan.
replaced all hoses.
coolant flush after flush.
nothing solved it.
now at the end of summer I put the Tstat back in. and when it gets hot in AZ I remove it.
temps over 100 degrees and jeeps just struggle.
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  #17  
Old June 14th, 2019, 18:42
asymptonic asymptonic is offline
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Re: It's been discussed a millions time so what's a million and 1 more

Quote:
Originally Posted by blu3fan View Post
before the trolls arrive.
last summer I was averaging 220ish anytime I stopped moving.
I replaced the fan clutch
got an upgraded water pump.
replaced the rad.
replaced the electric fan.
replaced all hoses.
coolant flush after flush.
nothing solved it.
now at the end of summer I put the Tstat back in. and when it gets hot in AZ I remove it.
temps over 100 degrees and jeeps just struggle.

That's certainly A solution, but something else is wrong there. Clogged heater core, something in the block, wrong coolant mix. I can't be 100% sure but I had trouble at 104 on hills at 80 mph for a couple years before a remaned engine swap for other reasons, and I did the HD radiator at the same time, and even with old hoses it seems to be almost impossible to get this anywhere out of 195-200 in all conditions now including Texas summers. XJs just aren't that different otherwise so physics dictates something else is going on.



I'm genuinely curious. I do have a manual, so I'm not cooling my transmission through the radiator, maybe that makes enough of a difference right on the edges.
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  #18  
Old June 15th, 2019, 17:46
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MichXJdad MichXJdad is offline
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Re: It's been discussed a millions time so what's a million and 1 more

I understand why XJs have issues with heat, engine bay doesn't breath, exhaust manifold placement, too small of a radiator etc. I don't like running at or over 200* at all. I have a newer rebuilt motor also with a new radiator. So My plan is to run a180* stat with a burp hole drilled in it, new housing and temp sensor with a bypass cut in the gasket, eliminate the clutch fan and go s-blade efan on the passenger side which I've adapted to a new stock fan shroud and a newer stock replacement fan on the driver side. I'll run a 180* stat inline on the heater hose for the pass Efan and my other fan is already on a switch. Hopefully this will keep it 190* or cooler. Air trapped in the coolant system seems to be a problem with the Xj.
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  #19  
Old June 15th, 2019, 20:58
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Runnin'OnEmpty Runnin'OnEmpty is offline
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Re: It's been discussed a millions time so what's a million and 1 more

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Originally Posted by MichXJdad View Post
...... run a180* stat with a burp hole drilled in it..........Air trapped in the coolant system seems to be a problem with the Xj.
I also drill a relief hole in the thermostat using a 1/8" drill bit. I think this helps to release trapped air.
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  #20  
Old June 16th, 2019, 07:12
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ehall ehall is offline
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Re: It's been discussed a millions time so what's a million and 1 more

The current mopar thermostat has a little wobble valve in it, coolant forces it closed but air can escape

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  #21  
Old June 16th, 2019, 12:21
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themauler themauler is offline
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It's been discussed a millions time so what's a million and 1 more

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Originally Posted by ehall View Post
The current mopar thermostat has a little wobble valve in it, coolant forces it closed but air can escape



I always buy dealer t-stat for this reason. If I am forced to buy a parts store t-stat then I drill a hole as mentioned above. Perhaps wrap your exhaust manifold with wrap to keep some heat out.

Four jeeps In counting I’ve yet to hold 210+ temps for more than a moment and I am using stock spec cooling system.


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  #22  
Old June 16th, 2019, 13:34
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Re: It's been discussed a millions time so what's a million and 1 more

Quote:
Originally Posted by MichXJdad View Post
I understand why XJs have issues with heat, engine bay doesn't breath, exhaust manifold placement, too small of a radiator etc. I don't like running at or over 200* at all. I have a newer rebuilt motor also with a new radiator. So My plan is to run a180* stat with a burp hole drilled in it, new housing and temp sensor with a bypass cut in the gasket, eliminate the clutch fan and go s-blade efan on the passenger side which I've adapted to a new stock fan shroud and a newer stock replacement fan on the driver side. I'll run a 180* stat inline on the heater hose for the pass Efan and my other fan is already on a switch. Hopefully this will keep it 190* or cooler. Air trapped in the coolant system seems to be a problem with the Xj.
That's a lot of work. There are other things you can/should do instead of trying to re-invent the wheel. Most of us here find that choosing a good, not a bargain brand radiator is 75% of the solution to solving high engine temperature. I do agree that the XJ is deficient when it come to the size of the radiator. However, I believe that a good radiator as well as other components of the cooling system (OEM) is more than enough to keep high temperature in check.

My XJ have a 13 year old radiator and that leaks ( it have a 7 psi cap for more than a year), dual e-fan with everything else OEM including the thermostat. I drive from North of Austin to San Antonio in stop and go traffic with the AC on high and my XJ do not get above the 210 mark in stop and go traffic encountered in the construction zone on I-35.

Is your 4.0 running lean? Is the catalytic converter blocked? Gears verses tire size? AW4 transmission or manual shift? Sorry, I did not read the post in its entirety. Many have thrown parts at their XJ in an attempt to bring the cooling system temperature down to later find out that (1) they purchase inferior parts or (2) the problem is somewhere not related to the radiator and other parts related directly to the cooling system.

Since I started on , there have been probably hundreds of threads relating to the efficient cooling of the 4.0L . Most have the problem solved by using direct OEM parts and/or good after market parts.
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  #23  
Old June 20th, 2019, 11:28
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Re: It's been discussed a millions time so what's a million and 1 more

It's not that much work, it's all easy stuff. It's got the aw4 and a external cooler is on the list also. It has a new stock replacement radiator, and a new water pump. Both done by the previous owner when the motor was rebuilt. I'm just not a fan of running any engine that hot (over 190). I come from the muscle car/street racing world, I like low operating temps, especially with a flat tappet cam, it's a personal thing. This is my 3rd 4.0 powered jeep, I love em, the factory just runs them too hot for my liking. If I can get it to run 180 on warm days with the AC on I'll be a happy camper
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  #24  
Old June 20th, 2019, 11:42
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Re: It's been discussed a millions time so what's a million and 1 more

That's understandable, but several people have reported degraded fuel economy when running 180 degree thermostats, seems like the 4.0 is just happiest at 195...
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  #25  
Old June 30th, 2019, 16:53
Jeepercreeper01 Jeepercreeper01 is offline
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Re: It's been discussed a millions time so what's a million and 1 more

****UPDATE****
Took some advice and dumped the coolant out and did a 50/50 mix. Seemed to run cooler. Az has been 105-110° consistently lately. I'm starting to suspect ac might be my issue.
Early mornings to work are nice and cool so ac is not necessary. The jeep runs about 190° at highway speeds. After work it's pretty hot and the Ac is on full blast. There is a atech of highway where I live that turns in to a parking lot with stop and go traffic for a couple of miles. The jeep will eventually hit 220° and the ac must be turned off. Once off and moving at highway speed she cools off back down to 210°.
This weekend I headed north to escape the heat of the valley. There were many steep hill climbs to which the Ac had to be turned off do to increased engine heat. However on the way home I left the Ac on through most of the trip back. Once I pulled in to garage and shut her down I noticed that she boiled over and completely filled the over flow tank.
Again, all cooling components have been replaced except the radiator. Which is a duel core all aluminum CSF radiator that is about 3 or 4 years old.
Could it be the Ac compressor over working the motor?
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  #26  
Old June 30th, 2019, 18:49
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MichXJdad MichXJdad is offline
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Re: It's been discussed a millions time so what's a million and 1 more

Not likely, is your Efan coming on when you turn the AC on? It should. If not start with fuse, relay, etc. to isolate the trouble. Without AC On it should come on at 215*, but as soon as you turn your AC on the AC clutch should engage and your e-fan should come on simultaneously.
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  #27  
Old June 30th, 2019, 19:09
Heavyopp Heavyopp is offline
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Re: It's been discussed a millions time so what's a million and 1 more

Quote:
Originally Posted by MichXJdad View Post
Not likely, is your Efan coming on when you turn the AC on? It should. If not start with fuse, relay, etc. to isolate the trouble. Without AC On it should come on at 215*, but as soon as you turn your AC on the AC clutch should engage and your e-fan should come on simultaneously.
Not on a 2001 — fan will only run at 215 or whatever the actual setting is — AC will not turn on the fan on 2000 and 2001

Now on my 96 the fan runs whenever the ac clutch engages

It does sound like you need to be certain your Efan is operating — you can test by jumping terminal 30 to terminal 87 where the relay mounts in the PDC — I would suggest using a fused jumper wire
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  #28  
Old July 2nd, 2019, 11:44
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MichXJdad MichXJdad is offline
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Re: It's been discussed a millions time so what's a million and 1 more

Add a switch to turn on your Efan there's a write up in the FAQ section, that way when ever your AC is on you can turn it on before it gets too hot. May want to consider an upgrade on your clutch fan to the ZJ clutch
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  #29  
Old July 2nd, 2019, 11:45
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Re: It's been discussed a millions time so what's a million and 1 more

You may be able to wire up a relay off the AC clutch relay to turn on the fan when the AC is turned on like the older xj's
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  #30  
Old July 3rd, 2019, 06:39
Jeepercreeper01 Jeepercreeper01 is offline
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Unhappy Re: It's been discussed a millions time so what's a million and 1 more

The efan comes on at 210 as well as when I turn on the Ac. All of this was replaced with new parts when the new motor was dropped in. Even though am not using the heater during this time of year. Would a plugged heater core cause this?
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