2004 Limited 3.7L overheating at idle?

[Kriszilla]

Hi all. I'm encountering a really frustrating issue with my Liberty.

It's a 2004 limited 4x4 with the 3.7L. If I sit at idle too long, the temperature starts to creep up past the center mark on the temp gauge and the A/C compressor starts cycling off and blowing hot air. Once I start moving again, the A/C comes back on and the temp will come back down to normal.

I have swapped the underhood relays for the electric fan and when I check it, it is spinning, although I don't know if it is supposed to be spinning faster under certain conditions, it always seems to be at the same speed.

My coolant level is great and hasn't changed, just had the coolant flushed several months ago when I had the radiator replaced.

I did replace the thermostat last night and I boil tested the old one and it was barely opening. The new one is definitely opening further but I'm still having the same issue.

I'm all out of ideas on this one, even after running several searches here on the forum. She's got about 105,000 miles on her now but she's been really good until this started happening.

Thanks!

Kris

 

[rockymountain]

Did they use the correct coolant when you had the radiator and flush done? The fan should be audible when it turns on; you should hear the whir. Your water pump could've went too.

 

[Kriszilla]

The coolant is the correct pinkish red stuff.

The electric fan is running, but it isn't loud at all. I can't really hear it over the engine noise.

If the water pump went out, wouldn't I have zero coolant flow and instant overheating?

Thanks for the ideas, every little bit helps!

 

[yellocoyote]

Water pump may be on the way out... but not completely failed yet. That would be my best guess.

 

[rockymountain]

Water pump may be on the way out... but not completely failed yet. That would be my best guess.

Lots of times one of the fins on the impeller break off. Still works, just not as good and barely enough. Its fine when you drive it because the engine is revving and spinning the pump faster.

When my fan turns on and I have the windows down I can feel the hot air blowing in and around my window. Its not a big gush of air, but you can feel it. You should definitely feel a rush of air if you're looking under the hood when its on.

 

[JeepJeepster]

Water pump may be on the way out... but not completely failed yet. That would be my best guess.

My thoughts as well. The impeller could be pumping just enough coolant to keep it cool while moving but not enough at idle to keep it cool. Its either that or the fan isnt putting out the air it should. It should be a two speed fan. I can clearly hear my fan over the engine if Im standing in front of it with the hood closed, its a pretty loud whine. While its running it puts out a lot of air if I put my hand behind it(dont get your fingers cut off!).

 

[Kriszilla]

Okay, I'll go and check the fan again on my lunch break to see if I can get an idea of how much air it's moving. I really hope it isn't the waterpump...

Let's say that for some reason, it's just the high-speed setting on the fan not working. Since I've ruled out the underhood relays I wonder about the following... If the fan relay under the battery has gone out, would the low speed setting still work, or would the fan not engage at all?

Possibly the coolant temp sensor?

 

[JeepJeepster]

The water pump really isnt a huge problem to change out. If you can do the labor yourself it should actually be cheaper than replacing the fan if the fan is bad.

The coolant sensor is a possibility. Using something like a infrared temp gun is a great way to check those. They are kinda pricey so it would be good if you knew someone that would let you borrow it. Point it right at the sensor when its up to operating temp. The sensor is on the top front of the engine just in front of the intake manifold.

Not sure on the relay under the battery. I would think if its bad then its bad and the fan wouldnt come on but again, Im not sure about that.

 

[Kriszilla]

I just checked the fan and it seems to only be running at low speed. Even when it gets up to operating temp with the A/C on, and then to the point where the temp gauge needle starts creeping up past normal it never goes into "hi" mode.

All the blades are there, no damage, and it's moving air, but not much and it's quiet. I've already swapped the relays for the low and hi in the engine fuse box with no change.

Not sure where to go from here... I'm not scared to change the water pump... okay, a bit, but I'm pretty mechanically inclined, but I'd rather not have to if I don't.

Thanks again to everyone for helping with this!

 

[AlexKJ]

BTW, I have the big shroud and the mechanical fan, so I can't see clearly if the electric fan is working or not... Any ideas?

Thanks

 

[JeepJeepster]

BTW, I have the big shroud and the mechanical fan, so I can't see clearly if the electric fan is working or not... Any ideas?

Thanks

Did we miss something here?

 

[Kriszilla]

Apparently we did miss something. lol... I think my thread just got hjacked.

Alex, Try standing back by the drivers corner of the engine bay with a really strong flashlight on the electric fan. You just might be able to see through the running fan to see your electric fan going. It should be simple to see if the fan blades are either sitting there or spinning.

 

[JeepJeepster]

Alex, Try standing back by the drivers corner of the engine bay with a really strong flashlight on the electric fan. You just might be able to see through the running fan to see your electric fan going. It should be simple to see if the fan blades are either sitting there or spinning.

Do you have the Mechanical fan or just the electrical fan? If you have the factory towing package you should have the mechanical fan+ the electrical.

 

[AlexKJ]

Did we miss something here?

No... it's a simple straightforward question about the same topic: electric fans... or there it's a rule about nobody asking questions aside the OP

Apparently we did miss something. lol... I think my thread just got hjacked.

C'mon!

Alex, Try standing back by the drivers corner of the engine bay with a really strong flashlight on the electric fan. You just might be able to see through the running fan to see your electric fan going. It should be simple to see if the fan blades are either sitting there or spinning.

Flashlight :-k pretty cool idea! idea.gif Thanks mate!

 

[LibertyFever]

No... it's a simple straightforward question about the same topic: electric fans... or there it's a rule about nobody asking questions aside the OP

C'mon!

Flashlight :-k pretty cool idea! idea.gif Thanks mate!

Yes, shine a bright light towards the electric fan should show you if it's running. And see if the radiator needs to be cleaned out. Somtimes the fins become clogged with mud.

Do a search of the forum and you'll find a lot of posts about engine overheating.
Here's one of my posts about transmission overheating; http://www.jeepkj.com/forum/showthread.php?t=35980
I've had both the electric and the mechanical fan fail. My Libby's transmission would reliably overheat while in 4WD but never while idling.

Oh and to answer Kriszilla's original question; If you've replaced the thermostat and the electric fan is operating then I would suspect the water pump. While you have it off replace the fan belt too. They usually fail together.

 

[J-Thompson]

Here is my .02 on it
it is the fan not the water pump
water pump going out will cause over heat at any speed ,most cases
not pumping enough water at low speed over heat even with the engine under little stress
at high speed it is pumping more but the engine is working harder so it needs more
water or coolant
The fan ,electric or mechanical, does almost nothing over 30 mph or so
over that it is all the wind that is being forced into the engine bay that is cooling the coolant
If you can not feel a good strong breeze off of your fan ,from under the Jeep, and it is not loud when standing at the front of the Jeep then the fan is not running fast enough
Think about this the fan knows the engine is getting HOT so it should speed up or get tighter if it is mechanical to over come the need for more air flow
our KJ would blow some mega air with just the electric fan ,blow the leaves off the trail on a hot dry day
The TJ is about the same and the VW has a fan that is stronger than both
you can feel the air at the back of the car when it is in high gear

 

[J-Thompson]

Apparently we did miss something. lol... I think my thread just got hjacked.

Alex, Try standing back by the drivers corner of the engine bay with a really strong flashlight on the electric fan. You just might be able to see through the running fan to see your electric fan going. It should be simple to see if the fan blades are either sitting there or spinning.

This will probably not work on his set up
I know that my TJ has an electric fan for the trans cooler and it will turn even when off due to the mechanical fan pulling air through it
as silly as this will sound you may need to try to "stop" the electric fan
I would try some light weight thread ,like the kind that sews on buttons
tie off the blades and then start the engine
if it breaks the thread then it is working if it sits there then it is not

 

[tjkj2002]

Sounds like you may have 2 problems at the same time,a bad water pump and a bad electric cooling fan.Seen it many times before.A water pump that is starting to go bad will overheat at low rpms but be fine at high rpm's.


Now the biggest ? is was the coolant HOAT coolant? Just becuase it was the right color does not mean it was the correct coolant as Dexacool is the same color as OEM HOAT coolant that came in your KJ.Dexacool or OAT coolants(AKA "universal" or "all makes/models") are well know for eating plastic and guess what your water pump impeller is? It's plastic.

 

[Kriszilla]

Huge thanks to everyone that replied, but I got the problem resolved.

It would seem that I missed the important step of firing up the jeep with the rad cap off and then firing up the heater to pull in the coolant from the other part of the reservoir. I likely had a trapped air bubble.

Once I did that, it hasn't overheated since and it's back to its usual self where the needle is firmly stuck on the center mark when at operating temp.

Thanks again to all!

Kris

 

[LibertyFever]

Huge thanks to everyone that replied, but I got the problem resolved.

It would seem that I missed the important step of firing up the jeep with the rad cap off and then firing up the heater to pull in the coolant from the other part of the reservoir. I likely had a trapped air bubble.

Once I did that, it hasn't overheated since and it's back to its usual self where the needle is firmly stuck on the center mark when at operating temp.

Thanks again to all!

Kris

Don't feel bad. In the past I've replaced many expensive parts to solve a problem only to realize it was the cheapest part that needed replacement

glad to hear you've solved the problem...