M1078 Engine Fan Issue

[cavetech]

My new truck has a fan problem that has me stumped. I have gone over the manuals again and again. I've got the parts memorized, but I ca't fix it.

When I was driving it home at 50-54 MPH I heard a loud intermittent noise and vibration. Had to almost crawl home because it wouldn't happen at slow speed.

Looking in the engine compartment with cab raised and engine off I could reach in and the whole cooling fan seemed loose and I could wobble it when I grabbed a hold of the plastic fan. I mean very loose and wobbly.

I studied the diagram of the fan assembly and clutch and figured the six bolts that hold the fan on had all fallen out. Today I unbolted the upper fan shroud and I can see in at the fan real well. All bolts seem to be there, the clutch assembly seems intact and everything tight. Except the cooling fan that I can grab and wobble a lot. Side to side and forward and back.

I am seriously in need of suggestions.

Could the fan be that loose by design? How do I stop the vibration?

Thanks, Steve

 

[dmetalmiki]

Surely if the blades are that loose, there is a bearing (bearings) in the assembly that is (are) worn out or loose? Keep us informed of the outcome of the checks dismantling and remedy.
Application of 30 psi (207 kPa) air pressure tofan clutch will free rotation of fan clutch andallow removal of fan clutch screws.• Both fan clutches are removed the same way.Fan clutch without studs shown.(8.2) Install fitting (2) in fan clutch assembly (3).(9) Apply 30 psi (207 kPa) air pressure to fitting (2).(10) Turn fan clutch assembly (3) until bolts (11) are visiblethrough fan clutch access holes (12).(11) Remove six bolts (11) from pulley damper (13).(12) Remove fan clutch assembly (3) from pulley damper

 

[cavetech]

Surely if the blades are that loose, there is a bearing (bearings) in the assembly that is (are) worn out or loose? Keep us informed of the outcome of the checks dismantling and remedy.
Application of 30 psi (207 kPa) air pressure tofan clutch will free rotation of fan clutch andallow removal of fan clutch screws.• Both fan clutches are removed the same way.Fan clutch without studs shown.(8.2) Install fitting (2) in fan clutch assembly (3).(9) Apply 30 psi (207 kPa) air pressure to fitting (2).(10) Turn fan clutch assembly (3) until bolts (11) are visiblethrough fan clutch access holes (12).(11) Remove six bolts (11) from pulley damper (13).(12) Remove fan clutch assembly (3) from pulley damper

The fan spins on the shaft with no air pressure. I see the six allen head screws that I believe hold the fan on.Guess I have to remove them. Didn't want to do that.

 

[mkcoen]

Take a look at my thread starting on page 70: http://www.steelsoldiers.com/showthread.php?152882-Working-on-the-M1078-LMTV/page70

Could be the same occurrence where the aluminum fan hub disintegrates. Be grateful that it didn't do it at 2500 RPM like mine did throwing the fan into the radiator. Get the new style fan clutch and new style fan (that has a steel hub not aluminum).

 

[cavetech]

Take a look at my thread starting on page 70: http://www.steelsoldiers.com/showthread.php?152882-Working-on-the-M1078-LMTV/page70

Could be the same occurrence where the aluminum fan hub disintegrates. Be grateful that it didn't do it at 2500 RPM like mine did throwing the fan into the radiator. Get the new style fan clutch and new style fan (that has a steel hub not aluminum).

My fan problem must be like that. I can move the edge of the fan forward and backward a good 3 inches. The fan also spins on the shaft with no air to the clutch.

Darn. Where can I buy a new clutch and fan?

 

[TNriverjet]

Often they can be found on the e(auction)site... None there today. Several vendors here probably have them. Eastern Surplus (SS vendor)has NOS fan clutches on their site. Also check with SS vendor suprman. Maybe SS vendor recksmilparts too

 

[cavetech]

I will take the clutch off tomorrow afternoon. I am apprehensive about it. If I take out the six allen head screws does that remove the clutch? Isn't there a bolt in the center?

 

[mkcoen]

If you're buying new parts make sure you get the new style. I don't have P/Ns but the way to check is the fan clutch has bolt studs coming out of it vs bolts going through the aluminum clamping part. I got my fan off eBay and it has a steel hub vs aluminum. If you're going through one of the parts houses like Eastern or Memphis Equipment ask them to send you a photo of the parts before you agree to buy. You can see what the new ones look like in my thread.

The fan is held on by the small allen head bolts and the fan clutch is held on by the bigger ones. No large bolt.

 

[Smike740]

The allen head screws you see will remove the fan, there are 6 more which can be reached through the front face of the clutch that holds the clutch on.

I replacd my fan and clutch a few weeks ago to the newer design for peace of mind, the new parts design is much improved. The fan hub is steel as well as the clutch body. The clutch is available on e-bay, search by part number KY10900800001

The fan is available as well if you search by the part number from the parts manual. When using the new clutch you also need to use the newer fan design

 

[Andyrv6av8r]

My 1079 had the same issue as yours. I had a local machine shop machine the original hub and make me a new adapter out of steel. I mounted the original fan without the rubber isolator. It worked great and haven't had any issues.

 

[cavetech]

If you're buying new parts make sure you get the new style. I don't have P/Ns but the way to check is the fan clutch has bolt studs coming out of it vs bolts going through the aluminum clamping part. I got my fan off eBay and it has a steel hub vs aluminum. If you're going through one of the parts houses like Eastern or Memphis Equipment ask them to send you a photo of the parts before you agree to buy. You can see what the new ones look like in my thread.

The fan is held on by the small allen head bolts and the fan clutch is held on by the bigger ones. No large bolt.

Understood. Can't thank you enough for the advice. I'll let you know how it is working out.

Steve

 

[cavetech]

Oh, Boy a problem. One allen head stripped out. Now the socket in the head is rounded out. No allen head wrench will fit into it. I have been trying to grab and unscrew it with vice grips, but it isn't working. Some of those allen head screws were very tight.

Can I use a grinding wheel to grind off the allen head, then remove the fan support plate and then the clutch? Then when the clutch is off go after the allen head screw with vice grips?

Continued: I ground a flat head screw slot in the allen head. Couldn't get the screw to budge. Vice grip didn't work. So I ground off the head. I figure I'll have the allen head screw shaft to grab when the fan clutch assembly is off.

My understanding of the service manual is that the fan support plate should now come right off. Or air applied to the clutch will release the clutch for the plate to come off. Tried both, but the fan support plate won't budge.

What could be stopping the fan support plate from coming off?

 

[reelclassic]

I checked all the bolts on my fan and they are tight. It still has a little play in it back to front - is this normal?

 

[Smike740]

The clutch shouldn't have play when there is no air applied and its locked. Also you shouldn't be able to spin the fan in this condition.

 

[cavetech]

My fan is way loose. Obviously needs new fan and clutch.

How do I get the plate off that is in front of the clutch? I have the allen head screws out, but the plate won't budge? I have no idea what to do next? My Kingdom for help!

Thanks, Steve

 

[Smike740]

Are you refering to the plate that is between the clutch and fan? If so its possible that someone put RTV sealer on the plate to hold it to the face of the clutch when they were assembling it. Mine came off easily however there was red RTV applied and my only guess was for this reason. if you need a picture of the clutch and plate disassembled as reference let me know. I would take a scraper or putty knife and work it behind the plate to seperate it from the clutch.

 

[cavetech]

I am referring to the very first plate you encounter when removing the fan/clutch assembly. It has to be removed before anything else. The military service manual calls it a "fan support plate". It is held on with 6 allen head screws. It is not inside or between anything. It could be called the outside or front-most plate. It is closest to the radiator. It will not budge with all 6 allen head screws removed. I blow air into the clutch fitting and nothing happens then either. I've tried getting it loose with a screwdriver. How does the plate come off?

 

[f8617]

My fan is way loose. Obviously needs new fan and clutch.

How do I get the plate off that is in front of the clutch? I have the allen head screws out, but the plate won't budge? I have no idea what to do next? My Kingdom for help!

Thanks, Steve

Hi Steve,
I assume your engine is a 3116...talk to your local CATERPILLAR mechanic.

 

[Smike740]

I am referring to the very first plate you encounter when removing the fan/clutch assembly. It has to be removed before anything else. The military service manual calls it a "fan support plate". It is held on with 6 allen head screws. It is not inside or between anything. It could be called the outside or front-most plate. It is closest to the radiator. It will not budge with all 6 allen head screws removed. I blow air into the clutch fitting and nothing happens then either. I've tried getting it loose with a screwdriver. How does the plate come off?

OK, unless something is different in regards to your fan and clutch. The plate you are referring to should come off easily once the 6 allen head bolts are removed. Basically there is the front most plate you are having trouble with next is the fan which has a rubber grommet in the middle and last there is a second metal plate then the clutch. Even if the front most plate is stuck to the fan the whole fan should come off the clutch. If not perhaps the rubber grommet is stuck to the clutch. Can you post some pictures?

 

[cavetech]

Yes, it is the Cat 3116 engine.

I am going after the plate with a screwdriver and a hammer.

I'll get some pictures.

I went to the National Guard Armory in town and the mechanics were very nice and helpful. They took me to see one of their trucks and I saw the clutch assembly wad different! They advised using a hammer. Going to try it.

I'll be back later with an update.