Cool KJ

[hyde]

Does your KJ's temp gauge stay just a bit tilted to the Cold half? I have never seen it pass over the halfway, never even on top of it. I always look at it straight and it is always just a bit before middle mark. Even when I rev the hell out of engine, and floor it and keep it there from 30 to 100 mphs.. it never gets warmer, never even on top of the center indicator. I don't want to jinx it.

Does that mean I got a cool KJ?

My uncle's ML350 is always way pass the center indicator.. I freak when I see his.

 

[MoladoGuy]

You are always looking to break your Jeep huh? My temp gauge typically never pasts the half mark. Even during the hot hot weather.

 

[Dave]

My factory gauge stays right on the half way mark also. I also have a gauge that reads in degrees. It usually reads 195-198 degrees when the factory gague is at the halfway mark. So if you're running half way on the gauge (and assuming it is right) that is probably your approximate temp.

The highest mine has been (that I noticed) was around 202 degrees towing. I am not sure what degree thermostat is in these things without looking it up but I would imagine around 198 or so.

Dave

 

[csukoh78]

Never once, not even once, have I ever seen mine move beyond the "just barely halfway" mark. And I mean never, during cold weather,or especially very recently where I was doing 90 mph on the interstate and 3pm in Nashville when my overhead temp read 109F, and the airport said 106F. It was so hot I melted the clutch on my AC compressor.

And yet the temp guage never moved.

 

[JeepJeepster]

Mine has never moved.

Haha, you are crazy in that Jeep hyedipin. You run the heck outta that thing. If yours makes it past 100k then mine will be good till 300k.

 

[KJ2005]

I'm in las vegas 110 deg heat 1/2 C/H on temp gauge, 4x4 in 105 degree heat 1/2 on temp gauge.

 

[Marlon_JB2]

LOL!!! No, never seen it move past just before halfway. I've seen mine DROP while running. (Diesels don't generate as much heat)

If I get stuck in traffic or in a drive through for whatever, it drops... violently, hehe.

 

[Corwyyn]

I'm in las vegas 110 deg heat 1/2 C/H on temp gauge, 4x4 in 105 degree heat 1/2 on temp gauge.

Yep, been wheeling in the middle of the summer down here and never had it budge. IIRC when we did the Coke Ovens run a couple of summers ago Vern had to strap another KJ up some of the obstacles because he was having t-case issues (stuck in 4-HI, trans temp light coming on) and I seem to recall him saying his didn't move even then. They stay real cool

 

[candpliberty]

We live in Las Vegas and have never seen more than half. We have a 06 renegade with trans cooler, automatic and 3.7. Either at 85 going over the rockies or rock crawling at 2 mph, never over half.

 

[hyde]

How does the Jeep keep engine cool like that? I am not the techie, but can I get a crash course on that?
Thanks.

 

[KeswickDave]

Recently towed 3500 lbs trailer 3400 miles, temp guage didn't move... always just a hair under halfway. We all have coooool KJ's

 

[Atrus]

I'll let you in on a secret - Jeep just actually maxed the gauge out at the halfway mark, and we all think our jeeps run really cool. The PCM just slowly moves the gauge to the halfway point and stops, there's not even a temp sensor. j/k

 

[hyde]

I was already mad that they didn't include oil and battery gauges on the KJ, now we find out that temp gauge is rigged.. what's next?

 

[o8k]

I was already mad that they didn't include oil and battery gauges on the KJ, now we find out that temp gauge is rigged.. what's next?

go buy a scan gauge is what =p
cowcatcher has a group buy going for bout twenty bucks off right now

 

[JeepJeepster]

The Jeep has a radiator with fluid running through it hyedipin. There is a pump on the front of the engine that is driven by the belt which pumps the fluid through the top hose, through the rad, then out the bottom hose. There is a thermostat on the bottom hose which opens and closes depending on how hot or cool the engine is. This keeps the engine at a constant temp since the engine is designed to run at a certain temperature. Its a good idea to change that stat out around 60k or so.

 

[hyde]

Scan gauge is too expensive just to see those stuff, I already responded to cowcatcher at LOST.

Thanks Blake,
Got the picture. It is still mind blowing that it keeps it at certain temp, despite the inferno that's going on under the hood. Might sound like a dumb question, but is that where they dump the antifreeze in the winter?

 

[Atrus]

Antifreeze and water should be at a 50/50 mix. Pure antifreeze and pure water BOTH have higher boiling and freezing points than a mix.

Thing to keep in mind is that yes, there's an inferno going on, but due to the drastic temps, heat dissapates exponentially due to the drastically lower air temp. What I mean is, I think heat will dissipate faster from something 1,000* when the ambient air temp is 70* faster than something that is 100* when the air temp is 70*. The 100* temp may drop 10* in 10 mins, where the 1000* might drop 250* in 10 mins. I never took thermodynamics though, maybe I am wrong.

FWIW, there is a point where the thermostat is open and the cooling system is at capacity so the temp is unregulated. Sounds like the KJ does a good job of this. My Prix had a 210* thermostat in it stock, but just because it opens at 210* doesn't mean it would stick at 210. I lowered it to a 180* stat, but it definitely was running hotter than 180. The cooling system didn't have the capability of keeping it at the thermostat temp. There definitely is a broad range of temps, the vehicle typically doesn't stay at a single temp.

Again, seems the KJ's system is very good compared to past vehicles I have owned.

 

[tjkj2002]

Just to clarify the raditor/coolant does not cool the engine,it is there only to stabilize the temps(the actual cooling effect is less then 20%).The main cooler in a engine is the engine oil,don't believe me look it up.Porshe has been using that principle for years and is still using,most 911's don't have a raditor or coolant,same for most motorcycles.


Oh by the way the KJ has a 195 degree t-stat,normal operating temps are 120-212 degrees for the 3.7L KJ.

 

[o8k]

Just to clarify the raditor/coolant does not cool the engine,it is there only to stabilize the temps(the actual cooling effect is less then 20%).The main cooler in a engine is the engine oil,don't believe me look it up.Porshe has been using that principle for years and is still using,most 911's don't have a raditor or coolant,same for most motorcycles.


Oh by the way the KJ has a 195 degree t-stat,normal operating temps are 120-212 degrees for the 3.7L KJ.

I never thought of it that way. but divineing what i know of it, ya the engine oil actualy has more surface area coverage of the engine and its components than the coolant. so it draws more heat energy off the engine by far. however once the heat energy is IN the material, coolant and oil, i would think the ratiator would have the supirior surface area for heat exchange. never cranked through the numbers to see who wins, kinda a neat factoid.

no wonder porshe just puts the radiator on the oil instead, i always wondered y the didnt go water cooled.... makes sense now

 

[JeepJeepster]

So why doesnt everyone use oil coolers if the oil cools the engine better than the rad does?