Runnin' Hot

JL Rockies · **Posted:** Sun Dec 07, 2008 10:48 am

Since last nite; when I drive at hi way speeds, the temp gauge sits at 3/4 mark instead of 1/2. If I put the AC on, it shoots for the red zone. The last time somthing like this happened, my AC condensor fan was bad. This fan is working this time but even when it didn't, things only got hot with the AC on and normal with it off.
Similar to last time, the temps stay normal under 55 mph.
I did get stuck in deep water yesterday for 5 mins. Maybe the bigger fan under the shroud is bad? Why would it run hot only on the hi way?
Any ideas would be appreciated brothers.

06 KJ Sport · **Posted:** Sun Dec 07, 2008 11:00 am

Have you checked your water pump for leaking? Or maybe your thermostat is giving up? How many miles do you have now?

JL Rockies · **Posted:** Sun Dec 07, 2008 11:25 am

66k miles. Where would I be looking for these leaks?

long_tall_texan · **Posted:** Sun Dec 07, 2008 1:07 pm

Look for a pool of coolant, or check to see if your coolant reservoir is low/empty. If it is, you have a leak somewhere in the coolant system. Hose, or water pump are likely suspects.

If you are full on coolant, it could possible be that your thermostat is stuck in the closed position and is not letting "cool" fluid to circulate in the engine. That is an easy fix. Look where the radiator hose goes into the block. Not sure if it is the upper or lower radiator hose. Just went out and looked at mine. I assume it is lower one. There is a flange bolted to the block that the hose connects to. Just remove the flange and the thermostat will come right out. You don't need to remove the hose from the flange. Go to the local ports store and pick up a new thermostat and flange gasket. Be sure to catch the anti-freeze to re-use, or buy new anti-freeze while you are at the parts store, because you will drain all of the coolant when you remove the flange.

Can someone that has replaced a thermostat on their KJ verify if it is the upper or lower hose? I haven't had to replace one yet on mine.

Here is the lower hose with the flange...

Here is the upper Hose connection:

JL Rockies · **Posted:** Sun Dec 07, 2008 1:24 pm

Mine doesn't look exactly like that since I have a CRD, that last pic would be my CAC hose. You may be right about the thermostat but I'd need help locating that on my rig.
I verified both fans are working by putting a piece of tape across the blade and starting the engine. After a bit, the tape broke.
If I had a mechanical fan the tape would've broke just as I started the engine correct?

snowsport · **Joined:** Tue Oct 18, 2005 11:52 pm **Posts:** 1211

long tall, it's the lower hose on the 3.7. I have no idea where to look on the CRD, I'm assuming it would be where the block meets the outflow hose....

Jeepjeepster · **Posted:** Sun Dec 07, 2008 2:11 pm

Usually if it over heats at high way speeds it can be a couple different things.

-Water Pump
-Plugged/bad Radiator
-I take it youve checked the fluid level and condition?
-Bad t-stat

Could something be wrong with that viscous heater that the CRD has? It shouldnt be engaged once the engine is up to operating temps.

JL Rockies · **Posted:** Sun Dec 07, 2008 4:16 pm

After my Jeep has been sitting while I pull out my wet interior, I noticed a puddle of coolant on the ground. I guess things point towards water pump now eh?

jeepkj02 · **Posted:** Sun Dec 07, 2008 4:45 pm

Sorry this is not very helpful, but A/C in december!! Lucky!! :roll:

06 KJ Sport · **Posted:** Sun Dec 07, 2008 5:35 pm

Start cheap and easy, thermostat, water pump, radiator...

Diggerfreek · **Posted:** Sun Dec 07, 2008 6:09 pm

most likely out of the weep hole on the water pump

JL Rockies · **Posted:** Sun Dec 07, 2008 6:27 pm

If the water pump is bad, would it leak only when the engine is running? Earlier in the day, I ran the engine long enough to watch the fan turn on. A few hours later, I moved it and noticed the puddle. After another hour or so, no new puddles.

Diggerfreek · **Posted:** Sun Dec 07, 2008 6:32 pm

it has to do with pressure. right now, the seal is at the point where it only leaks under pressure. after your engine is off, that pressure escapes with fluid and you have your leak. after there is no pressure, it won't leak

Jeepjeepster · **Posted:** Sun Dec 07, 2008 6:38 pm

Exactly. Probably a bad seal on the output of the water pump. Kinda common for some engines but idk any history of the crd.

long_tall_texan · **Posted:** Sun Dec 07, 2008 6:53 pm

JL Rockies wrote:

After my Jeep has been sitting while I pull out my wet interior, I noticed a puddle of coolant on the ground. I guess things point towards water pump now eh?

Wet Interior? Is your floorboard wet? If so, it could be a your heater core is leaking coolant into the interior...

ATXKJ · **Posted:** Sun Dec 07, 2008 9:28 pm

I'm kinda back at the "stuck in deep water yesterday" - did the deep water have any Mud? - could that mud be blocking part of the radiator?

(it could be hotter on the highway - if no air is flowing through the radiator)

gentle washing might be helpful - anything hard might bent the radiator fins.

JL Rockies · **Posted:** Sun Dec 07, 2008 9:51 pm

It was water, it was just past the "Liberty" trim on the door. I was rolling through water that deep all day but only ran into a problem when I got stuck.
The interior was wet because the cab slowly filled up while I waited for rescue. Mud and stuff on the radiator was the first thing I thought of so I hosed off the radiator as soon as I got home but no impact.

I drove home from my friend's house tonite (65 -70 MPH) along the way, the temp never went above 1/2 after driving 70 mph so now I am stumped. I am going to check in the AM for any puddles.

I am about to move to CO from FL and the KJ is my tow vehicle; I can't have this nonsense going on!

Jeepjeepster · **Posted:** Mon Dec 08, 2008 12:30 am

Did you actually spray the radiator out or just the inter-cooler and condenser?

Remember the radiator is on the back.

JL Rockies · **Posted:** Mon Dec 08, 2008 10:48 am

Hmm. I sprayed the front not the back. There's a big fan shroud on the back; is it easy to take off?

Jeepjeepster · **Posted:** Mon Dec 08, 2008 2:09 pm

Im not sure what kinda setup the crd has so idk how hard it would be to get off.

Its not that bad on a 3.7 unless you have the engine driven fan which would need to come off... Given you have the big shroud and not that little tiny one.

Ive sprayed my rad out from the back. Just gotta get down in there with a water hose and go at it.

Since you have a pusher fan how did you spray it at all?

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