M936 Wrecker Hydraulic Hoist Motor

[rivets1]

Have a 1984 AM Gen M936 5 ton wrecker. Hydraulic hoist motor is leaking. No exploded view in TM. Has anyone actually opened one up and attempted to replace gaskets,seals, bushings etc. ??

 

[gringeltaube]

The TM shows one gasket at least. The hyd. motor itself probably has O-rings to keep the housing parts sealed. Maybe it is time to replace those...?


G.

 

[m16ty]

Looks like a basic hyd motor to me. Easy to reseal. Just take it apart carefully, remember where all the parts go, and keep everything clean. Replacing the shaft seal should fix your leak.

 

[SLOrazorsedge]

Check with member M35A2-AZ, he's had his R&R twice I believe for repairs

 

[crasheej]

Make sure punch mark the parts so that you can put it back together right.

 

[5tonpuller]

Some have a thin gasket in between the parts. I all was heard the old guys call it onion paper. ( I don't know why )
What I have found out that shinny magazine paper is a good replacement. My .05 worth.
Matt

 

[doghead]

Onionskin Paper A lightweight, bond-type, thin and semitransparent paper used for duplicate copies of typed matter to save filing space.

A google search for onionskin paper can be elightening!

 

[Capt Pat]

If you're ever looking for a spare winch and motor for that rig, I've got one sitting here doing nothing but getting older and looking for a home.

 

[Hawssie]

Yeah that is just a basic gear pump, probably a commercial intertech (which is now owned by Parker). The gear pumps and motors are basically the same design and are easily serviced esp. if all you have is a leak. if its leaking externally its most likely the output shaft lip seal in the front. At least that is the most common place for them to leak as its a dynamic seal as opposed to the seals for the front and housing and gear section. You should be able to pull a part off of the seal if its readable and the motor should also have a part code on it if its something else.

 

[Hawssie]

I need to correct the last post. Should say " Yeah that looks like a basic gear MOTOR" next "for the front and REAR housing" and lastly "able to pull a part NUMBER off of the seal"

 

[rivets1]

Thanks for the reply info. Yes this motor is a Commericial Intertech product. We are going to open it up this week and look to replace o rings, seals, gaskets and hopefully repair the leak. Any additional info welcome. Will post our results when we finish.

 

[m16ty]

Any decent hyd shop should be able to get you the seals you need.

 

[Hawssie]

Check out these guys, they have some good info on determining what model and size you have. Commercial Intertech was a great company but ever since Parker bought it around 10 or so years ago the info,specs and parts breakdowns are harder to come by. Parker has bought up dozens of smaller companies lately and has made things more difficult with every one of them. http://www.knighthawksupply.com/commgen.htm

 

[rivets1]

Just to update this thread. We removed the motor, disassembled and found signs it had been apart before and "repaired". We got two rebuild quotes. Also found a hydrualic supply company here locally on Long Island and they advised they could get a new one from Parker for $1,600. Both rebuild quotes were higher, go figure. We ordered new on 3/24, Parker said they would deliver part in 6-8 weeks. It took 12 weeks but worth the wait and back on line.

 

[M35A2-AZ]

Just to update this thread. We removed the motor, disassembled and found signs it had been apart before and "repaired". We got two rebuild quotes. Also found a hydrualic supply company here locally on Long Island and they advised they could get a new one from Parker for $1,600. Both rebuild quotes were higher, go figure. We ordered new on 3/24, Parker said they would deliver part in 6-8 weeks. It took 12 weeks but worth the wait and back on line.

FYI, If your new Parker motor has a allen plug in the bottom side of it, you need add a case drain to it. If not you will be replacing it soon. I had my motor repaired two times before they told me it needs a case drain.

 

[70deuce]

M35A2-AZ, was there a tap point on the tank end fitting for your return line or did you have to drill and tap?

 

[M35A2-AZ]

M35A2-AZ, was there a tap point on the tank end fitting for your return line or did you have to drill and tap?

No there was not a tap hole. I drilled and tapped the fitting for the hose. It is a return line so there is no pressure. I did add a check valve on the case drain line.

 

[SLOrazorsedge]

Albert, my M936A1 looks identical to yours with the allen head on the bottom of the motor. With your modification how does the motor drain? It looks like it would have to drain uphill from the set up or oil from the return line would be flowing downhill to the motor? Is the goal to have the motor drain the hydro fluid dry when not in use? Thanks, Dale.

 

[M35A2-AZ]

Albert, my M936A1 looks identical to yours with the allen head on the bottom of the motor. With your modification how does the motor drain? It looks like it would have to drain uphill from the set up or oil from the return line would be flowing downhill to the motor? Is the goal to have the motor drain the hydro fluid dry when not in use? Thanks, Dale.

Here is my understanding (lookout LOL) When you are using the motor and reverse the motor there is an area between the seals that can build up pressure and needs to be able to bleed off that pressure, that is what the case drain does is bleeds off that unwanted pressure.
Are something like that. i not a hydro guy so that was my best attempt. Hope that helps.

 

[SLOrazorsedge]

Thanks brother, that makes sense. My motor does have a bit of seepage around the case seams and I sure as heck don't want to blow or prematurely wear a seal!