Overheating Hemi. No Fan? - JeepForum.com
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post #1 of 16 Old 08-01-2020, 08:48 AM Thread Starter
NevadaWheeler
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Overheating Hemi. No Fan?

My '05 WK w/ 5.7 Hemi overheated on a trip yesterday while stopped waiting for gas. It was towing my 24' travel trailer, but it has done that before with no problem. I was about 30 miles or so from home. After it cooled down and running with the heater on, it made it home on the highway at speed, but slow or stopped it heats up FAST! It seems like there is no fan blowing. I can't hear or feel air moving with it stopped with the hood open. I can't see it at all.



I've read that the fan is hydraulic and controlled by the FCM and that it may be bad. I've also read that there is a fuse that may have blown. Where would I look for the fuse, and what else should I check?


Also, since it's possibly related, the power steering pump has been going out for a few months, but is still working. It makes noise and is sometimes hard to turn in parking lots. I know I need to get that fixed. There doesn't seem to be any change in the power steering before or after this overheating started.


Thanks for any help you can give me,


Brizz


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post #2 of 16 Old 08-01-2020, 12:40 PM
acabtp
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absolutely related... the hydraulic system runs the fan so if it's out, you have no cooling while stopped. start by checking the fluid and pump and go from there. also check the steering rack and cooling fan hydraulic lines to see if you lost the fluid to a leak, since that also could have caused this problem. if the system ran low enough on hydraulic fluid that the fan stopped though, personally i wouldn't trust the hydraulic pump anymore since it was not lubricated while it was running dry or on foam.

you will need a vacuum pump and an adapter that fits the hydraulic fluid reservoir to properly bleed the hydraulic system once you've replaced the pump. running the engine and turning the wheels back and forth does not purge air out of the fan.

overheating an early hemi can be real bad since they can drop a valve seat and destroy the engine. i wouldn't press your luck doing it again.

'05 WK Limited 5.7 Hemi
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post #3 of 16 Old 08-01-2020, 12:42 PM Thread Starter
NevadaWheeler
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This morning I checked all the fuses and they appear good. I got close and looked and found I can see the fan. It runs slowly with Jeep cold and ran slightly faster after moving the trailer to the back yard. I don't think it was spinning yesterday when it was hot, as it is fairly easy to see when it is moving, but I didn't get as close to the hot engine then. On second evaluation I think the power steering is worse than before and it doesn't make as much noise.



I'm thinking the power steering pump is the root cause of all this.

Brizz


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post #4 of 16 Old 08-01-2020, 12:52 PM Thread Starter
NevadaWheeler
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Quote:
Originally Posted by acabtp View Post
absolutely related... the hydraulic system runs the fan so if it's out, you have no cooling while stopped. start by checking the fluid and pump and go from there. also check the steering rack and cooling fan hydraulic lines to see if you lost the fluid to a leak, since that also could have caused this problem. if the system ran low enough on hydraulic fluid that the fan stopped though, personally i wouldn't trust the hydraulic pump anymore since it was not lubricated while it was running dry or on foam.

you will need a vacuum pump and an adapter that fits the hydraulic fluid reservoir to properly bleed the hydraulic system once you've replaced the pump. running the engine and turning the wheels back and forth does not purge air out of the fan.

overheating an early hemi can be real bad since they can drop a valve seat and destroy the engine. i wouldn't press your luck doing it again.

Thanks for the info. I definitely don't want to F up the engine. The power steering fluid is just slightly low.


I pretty much came to the conclusion that the power steering pump is bad and causing the overheating. Thanks for reaffirming that.

Brizz


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post #5 of 16 Old 08-01-2020, 03:48 PM
Windexer
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I tested my fan could still do full speed by disconnecting the temperature sender then starting the car, the PCM will then request the fan go to full speed as a fail safe, if it doesn't go to warp speed then you need to look into the pump as poor fluid flow will most likely be the cause.

2005 WK Limited Hemi, 2" OME lift, header back exhaust, 245/75/R17 MT, Superchips tuned, Roof rack
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post #6 of 16 Old 08-01-2020, 05:08 PM Thread Starter
NevadaWheeler
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Originally Posted by Windexer View Post
I tested my fan could still do full speed by disconnecting the temperature sender then starting the car, the PCM will then request the fan go to full speed as a fail safe, if it doesn't go to warp speed then you need to look into the pump as poor fluid flow will most likely be the cause.

That sounds like a pretty good test. Where is the temperature sending unit connector that needs to be disconnected?

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post #7 of 16 Old 08-02-2020, 05:20 PM
Windexer
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Quote:
Originally Posted by NevadaWheeler View Post
That sounds like a pretty good test. Where is the temperature sending unit connector that needs to be disconnected?
From memory it was the one below the throttle body, I think there are a few different temp sensors as the manual says there is one under the AC compressor, beware that when I did this I got the usual Christmas tree lights on the dash but a code clear got me up and running fine again.
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2005 WK Limited Hemi, 2" OME lift, header back exhaust, 245/75/R17 MT, Superchips tuned, Roof rack
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post #8 of 16 Old 08-02-2020, 10:22 PM Thread Starter
NevadaWheeler
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Quote:
Originally Posted by Windexer View Post
From memory it was the one below the throttle body, I think there are a few different temp sensors as the manual says there is one under the AC compressor, beware that when I did this I got the usual Christmas tree lights on the dash but a code clear got me up and running fine again.

Thanks for the pic. Very helpful.



I bought a new pump last night, but they didn't have the right fluid to fill it up with. The guy behind the AutoZone counter first tried to sell me the wrong stuff insisting that it met Mopar specs and was what I needed. It did not meet MS-10838 specs and if not for this forum, I would have filled it up with the wrong stuff.



Anyone know what fluids meet the MS-10838 specs besides the Mopar stuff? Or who besides the dealer would have the Mopar stuff. I'd like to get some after work tomorrow and I don't get off until 6:00.

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post #9 of 16 Old 08-03-2020, 06:18 AM
caulk04
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I just get the dealer fluid, I've not seen anything easier to find that was definitive on meeting the spec.

08 Limited Hemi - wheels, tires, springs...ya know, stuff
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post #10 of 16 Old 08-03-2020, 07:32 AM
nvrdone1
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my 07 hemi started to run warm in traffic. everything checked good. fluid full etc. pulled the water pump and found the impeller had separated from the shaft so it wasnt turning. replaced pump and no more problems.
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post #11 of 16 Old 08-03-2020, 09:11 PM Thread Starter
NevadaWheeler
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Quote:
Originally Posted by caulk04 View Post
I just get the dealer fluid, I've not seen anything easier to find that was definitive on meeting the spec.
That may be what I end up doing, but the dealer closes be fore I get off work, so I won't be able to get any until this weekend.

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post #12 of 16 Old 08-03-2020, 09:20 PM Thread Starter
NevadaWheeler
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Quote:
Originally Posted by nvrdone1 View Post
my 07 hemi started to run warm in traffic. everything checked good. fluid full etc. pulled the water pump and found the impeller had separated from the shaft so it wasnt turning. replaced pump and no more problems.

I'll keep that in mind if the pump doesn't fix it, but since it ran fine at speed pulling the trailer, and only overheated while stopped or slow, I think it is the hydraulic fan not running. And I already have the pump.



Now I just need the MS-10838 hydraulic fluid.

Brizz


'05 WK 5.7 QDII, stock
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post #13 of 16 Old 08-03-2020, 09:36 PM
nvrdone1
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mine did exactly that - ran at normal temps at speed but started to get hot when caught in traffic. its called air flow - lots of air flow when moving, none when in traffic.
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post #14 of 16 Old 08-08-2020, 01:23 PM Thread Starter
NevadaWheeler
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I finally got to the dealership to get the MS-10838 fluid. Even the dealership tried to sell me the wrong stuff first. They looked it up in the computer and came back with ATF+4. After I again told them it needed to be MS-10838 they looked it up on google and found I was right. It seems the dealerships info on their own stuff isn't so great.


They did have the right stuff in stock though and were able to find it. $20 a bottle.

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post #15 of 16 Old 08-14-2020, 08:14 PM Thread Starter
NevadaWheeler
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I got the pump replaced today. Power steering works great and so far no overheating issues. I didn't check to see if the fan was running or not, but in stop and go traffic running the loaner pulley removal tool back to autozone with the A/C on full blast the temp stayed just under halfway as it did before the problem started.


I found a small leak in a hose coming out of the hydraulic fan that I will have to replace still. I'll have to get more MS-10838 from the dealership next Friday to do that.


Great right up by 99sajeep post #82 on swapping the pump out. I'll add that the threads in the center of my pump used to install the pulley onto the new pump were 3/8"-16.

https://www.jeepforum.com/forum/f67/...l#post41044261

Brizz


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