Air Leaking From NHC250 Fan Drive Clutch Actuator

[Rifleman]

I took my M925 for a test drive today, when i got back i noticed a big air leak. After stopping the engine the secondary air gauge was losing pressure fast. Upon opening the hood i found air leaking out of the front of the fan drive clutch actuator. So can i take the actuator apart and rebuild it, or is it a part that you just remove and replace with a new one?

 

[M35A2-AZ]

Some members here on SS have rebuilt them, but they are just a replacement part.

 

[porkysplace]

There are 4 threads at the bottom of the page under Similar Threads that should answer your questions.
[h=4][/h]

 

[machinist75]

It has three orings inside.

 

[aheilmann68]

Take apart, clean, test actuator, replace o rings and lubricate with a lubricant safe for the orings selected. Or buy new and just r&r.

 

[Tow4]

They are easy to disassemble and repair. I did mine without taking it off the truck and it took about 15 minutes.

 

[randygk]

I tried repairing mine, didn't work well. I purchased a new exact replacement from Eric's. Not cheap, but the right part and it's done.

 

[Rifleman]

Thanks Tow4, i took your advice and took it apart on the truck. I cleaned and polished all the brass parts, replaced the 3 O rings, lubed all O rings and bore with Parker O ring lube, reassembled it, it now works great.

Oh one more thing, some of the photos i have seen of other actuators taken apart have a brass needle valve stem with an O ring mounted on it's face. In my case mine didn't have the brass needle valve stem with O ring, mine was just a solid plastic needle valve stem with out any O ring at all.

Maybe mine was an older design or maybe a newer design, but i just want to let other members know that there are two types of valve stems on these actuators.

 

[machinist75]

Can you tell us where you found the large oring and possibly a part #? I found one that would work but didn't fit like I would like it to.

 

[Rifleman]

Machinist75,i am sorry to say i can't answer your question, when i left my last employer, they were closing down the whole plant, they were kind enough to give me two complete O ring kits. These two kits are made up of both Viton and EPDM O rings, and cover both thick and thin cross sections. The only problem is, the different compartments for each O ring size doesn't list a P/N, the only thing i can tell you is both kits were made by Parker.

 

[Tow4]

Machinist75, I got the o-ring kits Harbor Freight, you just have to match them up with what you take out. Or you could take the o-rings to a hardware store and match them there.