Thermostat - JeepForum.com
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  • 3 Post By kg6mov
  • 2 Post By StPaul59
  • 1 Post By 1996maroonzjf
 
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post #1 of 11 Old 01-23-2020, 08:55 PM Thread Starter
Tomcorr
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Thermostat

1995 Grand Cherokee Laredo 6 Cyl.
Bought it in Oct 2019, temp gauge always held and read about 210 degrees.
Since it gets really hot here in the summer I decided I was going change the thermostat to get it off the 210 mark.
Pulled out old one, it was a 195 put in a new 180.
Refilled with coolant started it up and it still reads about 210 degrees.
Nothing really changed.
Any thoughts on this?


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post #2 of 11 Old 01-24-2020, 12:29 AM
kg6mov
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If 210 is what the motor runs at, changing the thermostat isn't going to change that.

You didn't change your cooling capacity.

Try a new radiator and fan clutch if you want it to run cooler, but the 4.0 in the ZJ pretty much wants to run at 210 for the PCM to be happy.
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post #3 of 11 Old 01-24-2020, 06:51 AM
StPaul59
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There's a guy in the xj forum that swears by the 205 stat. I copied him
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post #4 of 11 Old 01-24-2020, 07:21 AM
LouC
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The stat will only regulate the minimum temp the engine runs at, not the max. The max temp is a function of the ability of the system to transfer the heat of the engine to the atmosphere. So unless you have a more efficient radiator, or bigger fan, you cannot really reduce operating temps. BTW, just about every Jeep 4.0 on the planet runs just fine at 210. As long as you are not routinely running above that, no need to be concerned.

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post #5 of 11 Old 01-24-2020, 09:21 AM
1996maroonzjf
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I’m with Stpaul59 on this one. The 4.0 runs most efficiently at 210. Period.

I’ve been running a 205* for years with zero issues.
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post #6 of 11 Old 01-24-2020, 10:04 AM Thread Starter
Tomcorr
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Quote:
Originally Posted by kg6mov View Post
If 210 is what the motor runs at, changing the thermostat isn't going to change that.

You didn't change your cooling capacity.

Try a new radiator and fan clutch if you want it to run cooler, but the 4.0 in the ZJ pretty much wants to run at 210 for the PCM to be happy.

The PO replaced the radiator, fan clutch and eng before I got it.

But the consensus seems to be - 210 is pretty much the mark.
Thanks.

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post #7 of 11 Old 01-24-2020, 10:21 AM Thread Starter
Tomcorr
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Quote:
Originally Posted by LouC View Post
The stat will only regulate the minimum temp the engine runs at, not the max. The max temp is a function of the ability of the system to transfer the heat of the engine to the atmosphere. So unless you have a more efficient radiator, or bigger fan, you cannot really reduce operating temps. BTW, just about every Jeep 4.0 on the planet runs just fine at 210. As long as you are not routinely running above that, no need to be concerned.
Quote:
Originally Posted by 1996maroonzjf View Post
Iím with Stpaul59 on this one. The 4.0 runs most efficiently at 210. Period.

Iíve been running a 205* for years with zero issues.
Quote:
Originally Posted by StPaul59 View Post
There's a guy in the xj forum that swears by the 205 stat. I copied him
ď Survey Says ď that 210 is pretty much the norm for the 4.0

Iíll see how it acts on a 120 degree AZ summer day with the ac pumping.

Thanks for the responses.

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post #8 of 11 Old 01-24-2020, 01:13 PM
StPaul59
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The xj guy lives in Seattle, so slightly milder than AZ. Make sure your radiator fins aren't blocked with lint. It can get pretty nasty and you can't see it easily as it is blocked by the condenser. It wouldn't be a bad idea to yank the rad and give it a good hose down. Then hose out the condenser if needed as well.
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post #9 of 11 Old 01-24-2020, 02:15 PM
LouC
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Also, there are foam strips on either side that are supposed to keep air from bypassing the rad, make sure they are still in place.
On our ZJ we chased a slight running hot issue for a while (one notch past 210 in summer) and replaced the rad, water pump and added an HD clutch fan. The thing that made the biggest difference was replacing the old thermostat with a new OE stat. That dropped the temps right back to where they were when it was newer.
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post #10 of 11 Old 01-24-2020, 02:26 PM
watertrucker
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I’m in SE California with about the same climate as AZ. My ‘98 ZJ 4.0 runs just a hair below 210 winter and summer. If your cooling system is in good shape you should be fine.
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post #11 of 11 Old 01-28-2020, 07:33 PM
gordoribm
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My 4L 96XJ runs cooler than 212 in Phoenix with AC blasting. Has Heavy Duty rad, HD fan clutch and 180 thermostat. I usually run 190-200 except hottest days in heavy traffic.
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