OK, this may seem like a stupid question on the surface, but what temp is this gauge reading? The reason I ask is that the scale on the left side of the 210* is not the same as the right side. Left side spreads 110* from 100* to 210* and right side spreads only 50* from 210* to 260*.

One line of thinking says that the 1/4 mark would be halfway between 100 and 210, so 155 which means I'm barely running 160-165. Another thought is that apparently as the needle moves to the right, every degree hotter is worth less and less needle travel, so maybe I could be running in the 180s tops.

FYI, I just installed a new 3 row rad, water pump and 180* t-stat and this shot is after (and while) driving 20+ miles on the highway. The needle pegs here and doesn't move.

 

On the Renix Jeeps I have read that the mark between 100 and 210 is supposed to represent 180. HTH not sure if that changed with the H.O. Jeeps.

BTW I'm jealous my gas needle never reaches the "F" cant afford but $ twenty or $ twenty five at a time.

 

I hope that's true on the HO as well. I would feel better if I knew it was running 185 or so. That makes sense because the 180* t-stat is apparently open constantly...needle doesn't flucuate except to creep up when sitting in a drive-thru or traffic.

I hear ya on the gas. I actually super glued it to the "F" so I would feel better. J/K I filled up Thursday for $3.45 before the hurricane effect took hold.

 

i cant read that gauge at all, its wayyyyy to clean

 

HAHA! I know, the elderly man I just bought it from was PICKEEEE about keeping it clean inside and out, but NEVER changed the coolant. Go figure

 

Hey Blue, I just realized that you are down in TX feeling the REAL hurricane effect. Didn't mean to complain about the extra $0.50 in gas prices when lives are in danger. Prayers are with you and everyone down there. Stay safe!

 

mine does not work.... so I dont read it,, but my rad cap has a temp gauge.. and last night I went to leave my GF at her house, it a 13 mile trip, and when I came back home, just for curiosity pop the hood to check it out and it said 165 degrees,, I have a 180 tstat.. so IDK if thats a good. or should it be a lil higher..

 

Your temp should never get below 180 and a 180 t-stat should not be in your jeep go get a 195 and do it right..These 4.0's are designed for up to 220 and should never get below 180..

 

why is an 180 tstat bad.. Ive read that is a common mod. and the cooler the better.. something like that.. also yesterday's night was a cool night,, normally it is about 180 to 200, with the 180 t stat,, just yesterdays night was way cooler than normal here in PR..

 

Your 4.0 is designed to run at 210..So basically what that means is if you want it to run at it's best and how it was designed you need to maintain the proper temp..That 180 t-stat mod is designed for engines that run hot now if your jeep with a proper tstat ran at 240 then yeah a 180 tstat would be good but since it runs cool you should be running at 195-210..If my engine run less then 180 I get error codes..

 

I have have no code. and I have been running that set up about a month now...

 

Belto what happens is the computer controls the fuel air ratio. Thus the rich/lean cycle. While the engine is cool the computer wants it in the normal range so makes it run rich. Once it gets to operating temp (190) then the computer leans it out. Lean means more air and less fuel to get the ratio right for that temp. So when you keep the engine too cool then it never leans out thus you are wasting fuel and can burn valves and clog the cat up with extra carbon. You also add carbon to the tops of the pistons which burns hotter and can (in extreme circumstances) burn a hole through your aluminum pistons.
HTH
Blue

 

well my temp gauge does not work, so the signal wont be good any ways,, also tonight I run it, and the rad cap said 120 and it deff feels hotter than that so probably my rad cap gauge is broken,, so I need to fix the xj's temp gauge to really check on it...

also right now the jeep is running the smoothest its ever run.. so I dont think there is nothing wrong with it..

 

Well, I'm starting to second guess my decision to put in the 180* thermostat. I'm sitting in the Arby's drive-thru today for about 10 minutes for a beef n cheddar which was well worth the wait BTW , and my needle creeps up and up past 210. I hear the electric fan kick on at about 215-220. The needle probably hits 225 and then slowly creeps back down to 215. I don't like it going that high and today was a fairly cool day.

I'm starting to think that my viscous fan clutch may not be working and that this 180* t-stat was not necessary. I don't think I'm hearing any whooshing sound like the fan is locked in and really pushing air. Anytime I look under the hood with it running, it's spinning. How can I be for sure that it's working correctly?

 

How old is the fan clutch? Basically if memory serves it should turn but no spin when you turn it with your fingers, basically should have some resistance..

I honestly wouldn't worry if in a drive through it warms up a bit.. You gotta consider you have no air flow, and you have tons of very hot exhaust coming straight at you..If the only time it warms up like that is in a drive thru then I wouldn't worry at all unless it gets well beyond that 220ish range..Your system is doing as it's suppose to, when it reaches above 215 aux fan comes on and cools it back down..