Mechanical FAN Woes

mtgstuber · **Joined:** Tue Sep 13, 2011 4:15 pm **Posts:** 66

It's been a while since I've been around here. What can I say, my CRD has been running (thanks to the help I've gotten here) and I've been busy. After trashing the rockers at 80k, I rebuilt the top end, installed 7volt stainless glow plugs, samco hoses, an inhose thermostat mod, and a green diesel tune and the machine has been running fine. I keep meaning to do a lift pump, but I haven't gotten back to it.

So I live near Spokane, WA and we just had a nasty cold snap. I parked the car at the airport Tuesday morning. I got back last night and it was about -3. The jeep didn't want to start. It took a lot of cranking but it finally started running, and I headed on my merry way. The dash gave me a low cool warning, which I thought was odd, but I figured something was just malfunctioning because of the cold.

I needed fuel, so I stopped at a gas station. Given the cold I just left it run while I fueled up. While there I heard a sound like a hood being slammed shut. Didn't think much of it.
As I pulled out of the parking lot my power steering stopped working. It sucked, but it was close to midnight on the coldest night of the year, and I decided to press on.

As I drove I noticed that the engine was coming up to temp, but I had no heat.

It's at this point that I start thinking -- gee I wonder if my accessory drive belt snapped -- but it's cold and there's no good place to stop the car and work on it so I press on.

About half way home, the electrical lights on the dash come on. Yep. Must be the accessory drive belt. The temp is wavering between 1/2 and 3/4 on the gauge with no heat in the car, but it's really cold outside so I figure the engine is fine and I press on.

About 3/4 of the way home the lights are time, the radio has shut off, the ABS, ESP, are complaining.

I manage to get it into the driveway and shut it down. I figure I'm off to buy a belt in the morning. Then I take a look at it:

CRDMechanicalFan by mtgstuber

The mechanical fan has basically snapped off of the mount! I'm having a WTF!? moment.

Any recommendations on the best repair? Just buy a new one? Switch to electrical?
Any thoughts on why this failed?

It also seems to have put some holes in the radiator, so it looks like I'll be replacing that too. :furious:

flash7210 · **Posted:** Thu Jan 05, 2017 2:33 pm

You are not the first to have this happen.
I dont know why it happens though.

WWDiesel · **Posted:** Thu Jan 05, 2017 2:35 pm

WOW! Thats UUUGLY!!!
You will need a new fan hub along with that new radiator.
Part no. for the fan hub is: 5142661AB
serpentine belt tensioner - 5072440AC
ID Parts and many others have them online and some are on eBay as well.. :google:

I would replace the serpentine belt, and serpentine belt tensioner pulley, HD fan clutch and fan as well.
If you want a lighter weight and more efficient fan, you can install a Mopar or GM 11 blade plastic fan like is used on gasser models. Much less rotational weight and moves more air as well....

A few of us have installed the GM 11 blade plastic mechanical fan along with a GM HD fan clutch designed for the V8 GM motor, its a direct fit, no mods required!
these are the part numbers and they are somewhat cheaper than buying the Mopar parts! NAPA also has them!
GM Severe Duty Fan Clutch NAPA 271625
Hayden Fan Clutch no. for GM: HY 2986
Four Seasons Fan Clutch for GM: FS46023 (almost identical to GM OEM fan clutch)

GM 11 blade HD Cooling Fan NAPA No. 8552223
Fan Part No. Interchange:
Dorman-620-602
GM-15976889 / GM3112109 or 15-80712 Replaces Original (OE) Part #:15976889

joe_ · **Posted:** Thu Jan 05, 2017 3:14 pm

Here's a similar thread from a few weeks ago: http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=85761

Basically there's a shaft going through the bearing, and the pulley is pressed on to that shaft. Eventually the bearing gets old/worn and seizes up, but the belt is still trying to spin the pulley, so it spins its way off of the shaft. Since it's already off, you might be able to replace the bearing and then press the pulley back on to the shaft, but honestly I'm not sure if I'd trust it. A new bracket is ridiculously expensive for what it is, but that's probably the way to go.

WWDiesel · **Posted:** Thu Jan 05, 2017 3:49 pm

Maybe we all should start removing the serpentine belt every so often and checking all the rotating bearings for any excess movement or resistance to rotation?
We all take this hub bearing for granted, so failure is hard to predict! :roll:

Preemptive replacement like we do on the timing belt, it's pulleys, and the water pump may be a wise decision and good insurance?
A single ~$160 hub bearing sure beats having to buy it AND a radiator and who knows what all else that fan can destroy.
I do feel better knowing I have plastic mechanical fan verses the OEM metal one which hopefully would do much less damage if it were to come off the hub!!!! :wink:

Thoughts!

mtgstuber · **Joined:** Tue Sep 13, 2011 4:15 pm **Posts:** 66

WWDiesel:

Thank you, thank you, thank you for the part numbers. Very helpful.

Out of curiosity why are you recommending that I replace the tensioner? I replaced it when I did the top end rebuild. I'm not seeing any visible damage.

I'm not sure I actually want a more efficient fan. It's hard to keep this engine warm as it is.

I did the inline thermostat mod to keep the engine warmer.

Joe:
Thanks for the link to the other thread, and the explanation. That was really helpful.

mtgstuber · **Joined:** Tue Sep 13, 2011 4:15 pm **Posts:** 66

Radiator and bracket ordered. I'm seriously thinking about reassembling it without any fan for the time being.

thermorex · **Posted:** Thu Jan 05, 2017 5:29 pm

Snap an efan and never use the mechanical one. You can completely bypass the fan pulley using a different size belt. I believe flash did this, or only for the viscous heater?

geordi · **Posted:** Thu Jan 05, 2017 8:30 pm

The plastic fan has more than enough energy to rip open the radiator too, if it flies off like that. The radiator tubes are right at the surface and very thin.

peteyz24 · **Posted:** Thu Jan 05, 2017 9:36 pm

I have been running without a fan since september, all is well.

WWDiesel · **Posted:** Thu Jan 05, 2017 10:56 pm

mtgstuber wrote:

Out of curiosity why are you recommending that I replace the tensioner? I replaced it when I did the top end rebuild. I'm not seeing any visible damage.

The suggestion was only if you have not recently replaced the serpentine belt tensioner. Figured while you were in there replacing parts it might be a preemptive move? :wink:

As long as it is not damaged and is fairly new, disregard....

Running without the mechanical cooling fan might be acceptable as long as you are not towing any loads and the ambient temperature along with the relative humidity remain mild in your area.... :roll:

mass-hole · **Posted:** Fri Jan 06, 2017 10:23 am

I am running a custom efan/shroud. It wasn't enough here in the summer but it's been fine so far this winter and certainly helps warm up the engine

Mechanical FAN Woes

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