[Richard]

Joe,

Use this https://www.amazon.com/Loctite-Pneumatic...B003XZB54O. On the threads. Don’t bother trying to find it at the auto parts store. I have tried a lot of stuff to seal hot ATF and this works for me like no other.

[kaptain]

Joe,

Use this https://www.amazon.com/Loctite-Pneumatic...B003XZB54O. On the threads. Don’t bother trying to find it at the auto parts store. I have tried a lot of stuff to seal hot ATF and this works for me like no other.

Thanks for Richard, another valuable tip. I gathered a lot of knowledge from you. 

I had never heard of or used such a product before, but I just ordered one at the link you provided.

[jdkskyking]

My coach is a 2005 #744. I found the hydraulic fan motor information stamped on a mounting flange:
Danfoss 74318-DFC
A040124EM

Danfoss 74318 Hydraulic Motor .pdf Size: 391.45 KB  Downloads: 15

My system has this hydraulic manifold/block.

       

Here’s the motor.

           

[sgc]

Well……rats.

The seal started leaking for the third time during our summer trip. ATF really does make a mess. You know the engineers definition of insanity, doing the same thing over and over but expecting a different outcome.

I had some communication with the engineers at Zero Max, the manufacturer of the OHLA. The version we have is a Newell special. They normally come packed with grease, instead of having an flow through lubrication system. Newell did it in a very clever way by routing the drain hose from the hydraulic motor through the OHLA and then routing the outlet from the OHLA to the hyd reservoir. So, taking the OHLA out the loop will mean the case drain from the hyd motor will now go directly to the hyd reservoir. 

But I am tired of cleaning up that mess in the engine bay, so here is my conversion to grease filled OHLA. I used Mobil 1 SHC grease, that is why it is red in the pics.

The first pic is of the OHLA with the original JIC hydraulic fittings. These are kind of different fittings than I knew about, but I learned they are JIC on one end and ORB on the other. ORB stands for O ring boss. It is supposedly a tighter seal, but only if you can tighten the nut to make the seal between the O ring and the case. Picture two shows the old fitting removed. Those marks on the nut are where someone in the past tried to tighten it with a hammer and a punch. No way a socket or wrench is getting in there because of the right angle.

Anyhoo, I replaced the right angle fittings with a #10 ORB plug. I drilled and tapped a hole in both the plugs and installed zerk fittings prior to installation. I removed the drain plug on the top and replaced with a vent plug. I did spring for new seals although that may have been overkill with the grease.

I will provide an update after next years tour of the country.





Oh yeah, one more thing, if you ever try this. The original plug on the top of the case was 1/4 NPT with an Allen recess. After breaking two Allen wrenches, I knew it wasn’t coming out. So I found a big nut that would just fit over the plug, and plug welded the nut to the plug. No problem removing after that. This is technically known in the south as the mo powah technique.



I know this is an old thread but as i am in the middle of the conversion to grease on Coach 545 (customer) i have a couple questions.

1. with the vent on the top is there any grease excursion from the temperature rise
2. if you add grease to the zerks in the oring boss plugs how is the grease going to penetrate the bearing with the vent on top as the grease will want to follow the path of least resistance 

My intention is to only use on of the orings plugs to introduce grease and drill and thread a couple of 1/8 NPT plugs on the outboard side of the bearings that would be removed during the maintenance procedure to allow old grease to be flushed as new grease is introduced to the system (of course the  vent would have to be plugged during this procedure) or am i missing something here. comments?  

[Richard]

Sorry if it took me a minute to locate the questions. No grease excursion. The engineer at the OHLA manufacturer gave me specific instructions not to fill the OHLA completely with grease 2/3 to 3/4 full was the sweet spot. I did pack the bearings by hand during reassembly. I think your idea is good, but possibly overkill. As they come from the factory, they are partially filled with grease with no provision for adding grease. The circulating ATF fluid was a Newell idea, one not necessarily recommended by the engineer I spoke with. The circulating fluid is what necessitates the Uber expensive seal on the outboard shaft. If you are concerned about longevity, you could partially fill the box with 90W hypoid just above the bottom race of the bearing, like an oil filled bearing on the wheel ends. After all, it is a common tapered roller bearing.

I have not added grease since the conversion.


But it was a good prompt for me. The grease conversion is still going strong after three summer trips totaling over 30,000 miles. No leaks, no problems, and the OHLA still spins easily and smoothly by hand.