Fixed to well??

[Tree Frog]

OK, is it possible to fix something to well? The Frog was running hot, 210 to 220, one time 240ish, on the interstate a lot and the outside temps have been kind of cool so I over hauled her system.
Today she got a 3 core radiator, high performance water pump from HESCO, high performance t’stat, new hoses and a new belt while I had it all apart.
Now, after driving her 40 miles this afternoon, in 93 degree heat, I couldn’t get her to 200!
What a difference!
Do you think something else could be giving me a false low reading?

 

[Nevada City Sparky]

You didn't say what year, but if a Renix system with the bottle on top, its very easy to get air trapped under the temperature sensor on the head. Pull it, let some water drain out and reset.

 

[Tree Frog]

Mine is a 95 with an open system.

 

[UNCC_99XJ]

bad temperature guage.....corroded terminals for the temp guage on the back of the dash also come to mind, as they do tend to go wacko when they get dirty enough.

But the fact that you noticed this right after doing all that work makes me think other wise.

How long after you did all the work did you drive it? I wonder if you still have some air trapped in there...

 

[Tree Frog]

The terminals are good. She ran hot yesterday, cool today after the work.

As for how long, she had 2 30min idles in the driveway before I went out. She never got hot in the driveway either. I'll use her for work in the morning and see how she does.

 

[UNCC_99XJ]

You said before it was running hot at 210-220. The 4.0 supposed to run at 210....unless you had a lower tstat in at the time.

 

[Tree Frog]

Well the factory t'stat is 195 not 210.

 

[Jay VT]

True, but the temp is not normally taken at the stat.

 

[cklaus]

People always seem to the think the 4.0 is SUPPOSED to run 210. the 4.0 is used in the Wrangler and the Grand Cherokees and in neither of them does the temp run 210 "normally." The 4.0 in our xj's isn't designed any differently to run a toasty 210 instead of the cooler temps in the Grands and Wranglers. The XJ's have a different radiator and different aerodynamics thus affecting our temps. Many XJ's are living long lives running the 210 but i'm betting it is warmer than what the engineers had in mind.

You didn't say what thermostat you put in it. Hopefully you didn't get a "hi performance 160 degree" as they sell online. I'd run a 195 or possibly 180 if you live in conditions where that is permissible (but many will suggest against this).

 

[Tree Frog]

I installed a hi performance/hi flow 195. Someone on here posted about it a while back, and that you could order it from Summit.

 

[cklaus]

you say it won't break 200, what temp is it at most of the time? If it is hovering at/right under 200 and won't go above it, then you did an awesome job on your cooling system. and you should be golden. I would only be concerned if it was staying significantly cooler as the metals in the motor will wear faster at too low a temp.

 

[Ecomike]

My 87 has yet to get over 200 F in two years. It held solid at 195 F today, and the radiator, bottle, cap, hoses, and fan clutch are already 2 years old. It reached 95 outside today.

OK, is it possible to fix something to well? The Frog was running hot, 210 to 220, one time 240ish, on the interstate a lot and the outside temps have been kind of cool so I over hauled her system.
Today she got a 3 core radiator, high performance water pump from HESCO, high performance t’stat, new hoses and a new belt while I had it all apart.
Now, after driving her 40 miles this afternoon, in 93 degree heat, I couldn’t get her to 200!
What a difference!
Do you think something else could be giving me a false low reading?

 

[Cherokeekid88]

I also replaced Everything but my radiator last summer, Also have both fans running at all times and put in a high flow WP and replaced that stupid plastic garden hose thing with a piece of brass and mine runs at about 190 all day long, only gets up around 210 when sitting in traffic

 

[Fourxfour79]

just a thought...I would also drain and flush the system again. When you replaced all that stuff you may have knocked some old gunk loose in the block that is now playing havoc with your thermostat. The only thing that made me think of this is that it doesn't sound like a consistent problem. If a piece of crud temporarily blocked your thermostat in the open position that could do it. And if all else fails, set up the camera, strip any good parts and :explosion

 

[pauldo39]

It seems as though you did a great job. I assume by "high performance tstat" you mean a balanced design. Those open exactly at their designated temperature, while standard designs tend to open about 10-15 degrees later. With a good radiator, pump, and everything else, you should be running at 195 or just above at all times. I did an experiment, trying both Stant/other aftermarket 195 thermostats and a Mr. Gasket tstat and the Mr. Gasket opened exactly at 195, the others opened around 205 (verified by ir thermometer, along with temp gauge). Now, if you had put in a 160 tstat, it seems as though you have good enough components to actually keep it running around 160-170, and that would be "too good" of a job, per se. But it seems as if your system is in great shape. I'm actually thinking about starting a thread where everyone lists exactly what components they have in their system, where they live, how they drive, and what the normal temp is, if they're happy with the setup, etc. I think that would be useful information for anyone with problems in the future (which there no doubt will be).

One thing I don't understand is people who claim their jeeps run "at 160 on the highway, only get up to 210 while idling, etc", with the recommended tstat, and say that's a good thing. If your tstat is functioning that will NOT happen (unless you have a 160). If your temperature fluctuates over 50 degrees while driving the thermostat is not closing (assuming you have the recommended 195).

Well, now I'm just rambling! Anyway, glad you defeated your cooling demon, I finally did as well not too long ago and it was quite the relief.

 

[pauldo39]

People always seem to the think the 4.0 is SUPPOSED to run 210. the 4.0 is used in the Wrangler and the Grand Cherokees and in neither of them does the temp run 210 "normally." The 4.0 in our xj's isn't designed any differently to run a toasty 210 instead of the cooler temps in the Grands and Wranglers.

I've had a 2002, 2004 Wrangler with the 4.0 and driven plenty of other Wranglers in both Wisconsin winters and Houston summers, and all of them ran at exactly 210, give or take MAYBE 2 degrees either way. I drove the 2004 Wrangler off the dealership lot a few years ago and the needle was painted on 210, leading me to believe it was indeed supposed to run that way.

However, I will certainly agree with you about the design of the XJ cooling system; ie tighter clearances, oddly shaped radiator; make it have to work harder than, say, a wrangler cooling system. But in my experience this means if both systems deteriorate over age, the XJ will be the first to show symptoms in terms of running hotter than normal; they will both run at the same temperature when in optimal condition.

 

[1985xjlaredo]

With all of the upgrades you have done I would think that you'd expect the thing to run a litle cooler.

 

[Tree Frog]

It seems as though you did a great job. I assume by "high performance tstat" you mean a balanced design. Those open exactly at their designated temperature, while standard designs tend to open about 10-15 degrees later. With a good radiator, pump, and everything else, you should be running at 195 or just above at all times. I did an experiment, trying both Stant/other aftermarket 195 thermostats and a Mr. Gasket tstat and the Mr. Gasket opened exactly at 195, the others opened around 205 (verified by ir thermometer, along with temp gauge). Now, if you had put in a 160 tstat, it seems as though you have good enough components to actually keep it running around 160-170, and that would be "too good" of a job, per se. But it seems as if your system is in great shape. I'm actually thinking about starting a thread where everyone lists exactly what components they have in their system, where they live, how they drive, and what the normal temp is, if they're happy with the setup, etc. I think that would be useful information for anyone with problems in the future (which there no doubt will be).

One thing I don't understand is people who claim their jeeps run "at 160 on the highway, only get up to 210 while idling, etc", with the recommended tstat, and say that's a good thing. If your tstat is functioning that will NOT happen (unless you have a 160). If your temperature fluctuates over 50 degrees while driving the thermostat is not closing (assuming you have the recommended 195).

Well, now I'm just rambling! Anyway, glad you defeated your cooling demon, I finally did as well not too long ago and it was quite the relief.

I used the Mr. Gasket high-performance high flow thermostat from Summit.

http://store.summitracing.com/partdetail.asp?part=MRG%2D4365&autoview=sku

 

[pauldo39]

With all of the upgrades you have done I would think that you'd expect the thing to run a litle cooler.

Why would it run any cooler if a 195 tstat is being used?????? The 195 keeps the temperature from dropping BELOW 195! If you had a racing grade cooling system with a 195 degree tstat, the temperature would run at..... 195!

BTW, I also use the Mr. Gasket 195 and it works well.

 

[Ecomike]

FYI:

I ran some temperature tests with an IR gun recently and found that on my Renix 87 the block temperature runs the same as my gauge (sensor is in the block) and they run from 165 F (I have a 165 F thermostat in mine) to at worst 200 F. The thermostat housing runs the same temperature as the block and my dash gauge.

The return coolant exiting the radiator runs 10 to 30 F cooler than the coolant intering the radiator. Also the electric fan on my Renix turns on at 195 F block temperature which is about 185 F radiator exit coolant return temperature, and cuts back off at 175 F radiator coolant exit return to the block temperature and 185 F block temperature. Note that the electric fan thermal switch in the Renix years (87-90) was in the cold radiator side of the Radiator, which in my opinion is, was the superior location for it from a cooling stand point. In 91 they turned the cooling fan operation over to the Chrysler PCM computer which reads the thermostat coolant temperature only.