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Running Cooler

J

jeepguy97

NAXJA Forum User
Location
clearfield, pa
My XJ (97, 4.0, AW4) runs a little above 210 or right at 210 most of the time and for some reason I just can't come to live with it. Every other vehicle i drive runs at like 190 and i was just wondering what would be the best way to lower the temp just a little so I can feel better about it.
 
Turn your heater up full :D
Mine always runs a little cold. around 190-200, I´m on my third thermostat and have checked my sender with an eletronic thermometer, it reads fairly true. Finally decided it was just the nature of the beast. Have noticed, many thermostats are a sort of thing, they may say 192 or whatever, but generally open at plus or minus 5-10 degrees of rated temp.
Couple of things to keep in mind, the temp. gauge is rarley exact and the sending unit, isn´t actually at the hottest spot in the circulation system.
 
jeepguy97 said:
My XJ (97, 4.0, AW4) runs a little above 210 or right at 210 most of the time and for some reason I just can't come to live with it. Every other vehicle i drive runs at like 190 and i was just wondering what would be the best way to lower the temp just a little so I can feel better about it.
Click to expand...

210 is fine. If yer realllly worried about it, can slap on a GOOD elec fan, but seriously 210 is on the mark.
 
Believe it or not, you don't WANT your XJ to run any cooler than that. Seriously. Just accept that this is the temperature that the designers INTENDED the XJ to run!
 
OK OK, Ill come to terms with myself, but does anyone have a schematic so I can at least put my electric fan on a switch so I can turn it on should I need to. I would like it to still work by itself as it needs also.
 
Just a reminder..get a good fan, if you go that route. I did the 'on sale, only 99 bucks' checker auto route..and that didn't cut it. Find one with superior cfm's. A search would prolly cover it, gawd knows we've talked about xj's over heating enough...
 
Almeek69 said:
i put a three core rad in my 87 and a 160 therm. and it doesn't get over 200. i like it.
Click to expand...
Same here, even stop and go at 100 deg outside temp. No change in mpg or performance, except my oil doesn't thin out as much, has higher pressure, and I think about all those extra miles I'm getting out of hoses, transmission, etc.

The late 80's were all about a new priority, without a lot of technology, on emissions and emissions standards. They had to make sure that any sampling from production exceeded some number for the year. Making it hotter helps just a bit, and gives some margin for error in other parts of the system. It is NOT good for the engine. BELOW 160 is (was) bad, but with more pure oils now, even that isn't as bad as it was. It's designed to run hot because it's an easy tweak the mfg could do to meet the numbers, not for engine or component longevity or for the buyer. And besides, heat related failures usually don't happen right away, so they wouldn't incur warranty costs, and no one would really complain about needing a tranny overhaul at 80k miles or so, even if it could go more than twice that at 20 deg less temp. Who would know? ;-)
 
skipc said:
The late 80's were all about a new priority, without a lot of technology, on emissions and emissions standards. They had to make sure that any sampling from production exceeded some number for the year.

...

Making it hotter helps just a bit, and gives some margin for error in other parts of the system. It is NOT good for the engine. BELOW 160 is (was) bad, but with more pure oils now, even that isn't as bad as it was.

...

no one would really complain about needing a tranny overhaul at 80k miles or so, even if it could go more than twice that at 20 deg less temp. Who would know? ;-)
Click to expand...



Uh...

[a] If the high temp were strictly an emissions issue, then YJ's, TJ's and ZJ's would also run at the higher temp. As I understand it, only XJ's do. It's more a matter of limited airflow in the restricted engine compartment (which was a pre-existing part of the Jeep, before the 4.0 was stuffed in there). A higher operating temperature allows the same radiator to extract more heat (BTU) because of the higher temperature differential with the air.

Likewise... with modern oils, higher temps are not as big of a problem as they would have been in years gone by. I don't think i agree with the notion that the oil doesn't work as well at cold temps.

[c] Tranny overhaul at 80k? From what I gather, the AW4, as used in the XJ, is about the most bulletproof automatic tranny in existance! I'm about to change my belts "just because it feels right to do so" at 60k.

Personal opinions can differ... but I think the proof is in the fact that so many "hot" XJ's live very long, prosperous lives...

Den
 
OK I feel better now because by the time my XJ hits 265,000 miles it will probably be a strictly trail Jeep with a full cage and no top or doors. Seriously though i would like to have a switch so I know that if things should heat up on the trail i can control things a bit. Do you think this is a good idea.
 
jeepguy97 said:
OK OK, Ill come to terms with myself, but does anyone have a schematic so I can at least put my electric fan on a switch so I can turn it on should I need to. I would like it to still work by itself as it needs also.
Click to expand...
 
for a switch to activate your electric fan go to e-bay. Look under the heading jeep cherokee. There are units made up just for the job complete with plug and switch. Not too expensive either.
 
FYI
While your engine is running you can unplug the temp sensor at the thermo housing the fan will kick in. That's part of the control circuit for '91s and later, you could wire in a switch to cause this "open" in the circuit. Hasta
In your under hood fuse box is the relay for the fan, I think terminals 1, 4 are the control circuit. search for other threads.
 
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