HMMWV 6.2 Fan clutch question

[0311retired]

Good morning Gents,

My water pump and fan clutch went out on me. Water pump was easy to find in parts store but not the case with the hydraulic clutch. Also, I'm little confused about the clutch. There are few listed online but here comes the confusion. Some listings show the clutch is for "6.2 or 6.5" ...... The question is if the hydraulic clutch is the same for both engines or is there specific clutch for each engine.

Thanks a bunch for your help.

 

[jeffy777]

How do you know the fan clutch is out if you don't know where it is?

 

[0311retired]

How do you know the fan clutch is out if you don't know where it is?

There are few of them listed online for sale but in the description it is not clear for what engine. In the description it shows "6.2 or 6.5"........

 

[jeffy777]

What I was referring (poorly) to was normally I start with anything that is on the part. On another forum they had Kysor stamped on it. Later it was found that it was Kysor MD9 by borgwarner and the part was sourced.

I meant to type something different but my wife was nagging me and I wrote something that sounds different than what I thought I was typing. She nagged some more I hit post and did what she told me to do. I normally try to read what I write. I should not have hit post.

 

[gcbennet]

From what I understand the fan clutch assy isn't engine specific. The only difference would be the pulley for A2 vehicles.

 

[Bulldogger]

It seems odd for both the water pump and fan clutch to go out at once. Have you tried pressurizing the fan clutch w 90+PSI air? I think of them as fairly simple, and hard to break.

Sorry to hear about the water pump. That is annoying to get off. Common advice here is to bite the bullet and remove the hood and the whole radiator stack. It's dirty work but then you're not having to work with your fingertips while leaning over the engine bay.

Bulldogger

 

[0311retired]

Bulldoger,

Yes, very odd that they went out both at the same time.

I have my local shop on it. The boss called me and said to come look at it. Once I got to the shop he already had the clutch out and showed me how the clutch was grinding and wobbly.
Do you know if the clutch is the same for the 6.2 as well for the 6.5?

 

[juanprado]

In my other lifetime selling parts, I saw many examples of them going bad together or causing one to fail. Both are shafts with bearings and when a water pump is allowed to tear itself apart it can cause an imbalance wiping out the fan clutch or vice versa and taking fans out. I also saw many fail catastrophically and take out a radiator. Most major new water pump manufacturers ( I don't think any one rebuilds nowadays as everything is sourced overseas) strongly recommend both to be changed at the same time. Just cheap insurance due to the high cost of labor to redo. Most pro shops will change both to avoid comebacks.

 

[0311retired]

In my other lifetime selling parts, I saw many examples of them going bad together or causing one to fail. Both are shafts with bearings and when a water pump is allowed to tear itself apart it can cause an imbalance wiping out the fan clutch or vice versa and taking fans out. I also saw many fail catastrophically and take out a radiator. Most major new water pump manufacturers ( I don't think any one rebuilds nowadays as everything is sourced overseas) strongly recommend both to be changed at the same time. Just cheap insurance due to the high cost of labor to redo. Most pro shops will change both to avoid comebacks.

juanprado,

You are absolutely right.

 

[0311retired]

I have NOS fan clutches. $200ea plus trip.

Thanks recksmilparts. I already got one earlier today.

Thanks again.

Mark

 

[1919]

I know this post is a little old, so sorry for that. I am in need of a new fan clutch or a rebuild kit. I have it out along with the whole front end to replace the water pump and I do not want to do this again. Do you still have the NOS ones? if so would you ship it to me? Any one know of any other sources? Seems the only thing I can find is Kascar for $479 and their rebuild kits seem a little outrageous too. I already bought a nos friction piece off ebay so all that I really need is the seals and bearings. I can't see the springs being bad...

 

[NormB]

I'll chime in, too.

Does anyone have a reliable, reasonable source for rebuild kits for the fan clutches? All I can find online are the liners/friction material. I have one that will need bearings, seals, if it can be resurrected at all.

In hindsight, the $200 price from two years ago seems reasonable. So too does $1200 for a red dot AC kit (last time I saw THAT price was a little over a year ago) - can't touch 'em for less than about $2500 now.

I've seen the clutches pop up on epay from time to time for under $400, but mostly they're closer to 5 or 6 hundred new.

Thanks in advance.

 

[ken]

Norm,
I too was in your shoes last winter. I took it apart and took the bearing to a bearing supply. I don't rember the number but they matched it up for $12. For the o rings I got a o -ring kit from herbor freight for $5. Then matched it up from the kit and I was back in business.

 

[NormB]

Norm,
I too was in your shoes last winter. I took it apart and took the bearing to a bearing supply. I don't rember the number but they matched it up for $12. For the o rings I got a o -ring kit from herbor freight for $5. Then matched it up from the kit and I was back in business.

Call me old school. I just hate not being able to fix stuff.

When I was in high school back in ‘75, I rebuilt an English Ford Cortina transmission. Had spares, matched up parts I’d need, then found the most out of the way bearing shop (the only one, IIRC) in town, took like two hours to get to by bus with two transfers then I said the heck with it and hitchhiked home. Tranny went together no problem. Thing was smooth as silk when I got done.

So I found the seals for the fan clutch between two different online sources, local ACE hdwr has an amazing collection of viton O-rings, maybe something the right size. If not, flightsource has them - allegedly - according to nsn-now.

I’ll put together a list, THEN dismantle the thing. Would be nice to have another (bought one from reksmilsparts) “spare”. Events like what Gen’l Hood went through this past year seem to indicate you can’t have enough hydraulic fan clutches.

Norm

 

[86humv]

Might have some laying around....re builts or new.

 

[NormB]

Might have some laying around....re builts or new.

Thanks, Greg. I just bought one, but others might be in need. I just hate to use the old one as a paperweight if maybe $75 in parts and a little time can bring it back to useful life if not for me then for someone else.

 

[ken]

I got a spare WP pulley from the auction site. It's chucked up in my Lathe now. I'm going to modify it to fit a thermal fan clutch like the civi H1 with a 6.2. I know the fan is a different part number and a different bore. So I will eather buy a new fan or use a 20 inch metal 6 blade fan I have. They only reason I would need the hydro clutch is if I'm going to ford water. So I can reinstall it the next time a hurricane comes if need be. Other wise no more leaks, bad modules or shorted out valves.

 

[90Jimmy]

I have had my1989 M998 for about 3 weeks. After several short shake down runs and some research on this forum I am sure now that my cooling fan locks up at 160 on the gauge and the truck has yet to get hotter than 190. At 160 there is a loud whining noise from the Cadillac valve area and a noticeable decrease in engine power. Ok, now for the question... I understand that unplugging the Time Delay Module should engage the fan, but mine appears to be the opposite. When I unplug it the whining noise goes away and the engine regains lost power. Any guidance on this would be appreciated, maybe I am misunderstanding how the system works? I do know the fan should not engage at 160 so I want to replace the necessy parts but am totally confused right now. Thanks for any help

 

[papakb]

The way the system is designed the fan solenoid de-energizes at around 220-230 degrees and that causes the fan to run until the temp hits the 190 degree mark. If you have a discrepancy there it's probably due to a bad temp gauge. This de-energizing of the solenoid causes the fan clutch to engage and cool the engine down. It's backwards from what you'd normally expect but the theory is that if the solenoid fails the fan engages and cools the truck all the time and lets the thermostat control the temperature. When the fan is engaged is when you hear the loud rushing sound and get the miserable drop in power. That fan system uses about 10 HP and you'll know when it engages. When the engine is cool, the solenoid is energized and the sound you hear is the hydraulic fluid moving thru the valve. A common fix for this is to loosen the clamp that holds the solenoid in place and wrap a piece of rubber around it to deaden the sound.

If your system isn't working this way maybe someone reconnected the hoses the way they thought it was supposed to work and it is operating backwards. There's a great section in the -20 manual about troubleshooting the fan system you might want to take a look at.