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PORTAL BOX GREASE

12K views 46 replies 27 participants last post by  andre_ 
#1 ·
Hi All

Just a quick question. Can a grease be used inside the portal box instead of SAE 90 oil?
I know that a special grease can be used on a landrovers front hub, especially when the swivel hub gets pitted and the oil never stays in.

thanks
 
#2 ·
I would say yes depending on your application. The grease also needs to be low viscocity. However most of the swivel ball rover guys ended up using 90wt and just accepted the leaks. Largely because we broke so many CV's.

Regardless, I am confident if you used the thin one shot type grease used in landrover a you will be fine so long as you don't operate at high speeds. Heck I know guys that ran grease in their diffs.

What model Unimog are you talking about.
 
#7 ·
I guess if you wanted you could use the John Deere corn head grease. This grease goes to a liquid 90w gear oil with heat and back to somewhat solid when it cools. I have used it in PTO bearing blocks with no leaks.
 
#8 ·
It has been discussed on the "other" Mog List, and at least 1 person is using it successfully in his SBU and reports cooler portal temperatures. If somebody would like a link to that thread send me a PM as I don't think the Mods would allow it in this forum. I plan to pack some for emergency repairs on the trail
Rick
 
#10 ·
Yeah Ham runs a mix of grease and lube oil and reports it does okay but ambient and operating temperatures will play a big part in the mix.
 
#13 ·
I have been using corn head grease (John Deere version, NLGI 0 viscosity...look it up) for several years in the U1300. This was not done for leak stoppage but for better lubrication and lube control.

Check this out:

As we all know, the portals on the U1300 have problems. They lose their lube into the axle, and the bearings break down, and that is not necessarily cause-effect. Many of us have never run the portals without lube but have had bearing failures. Big tires, long distance driving, and faster speeds no doubt contribute.

Grease can have a better EP rating than oil, and it does not migrate as easily. Plus, the portal can have a higher level of grease in it than oil without leaking.

As stated above, the temperature of the portals dropped by 10 deg plus when grease was put in. BTW, the grease is not liquified by temperature but by motion.

There may be another factor to consider. The U1300 portals require shimming to position the big gear. If this is not done correctly, or with wear and movement, the big gear can wear on the inside of the housing, producing metal chips or slivers. These will settle to the bottom of the case during inactivity, right onto/into the large bearing race. It's the bottom part of the big bearing race that fails. Coincidence? I don't think so. The grease holds the chips in suspension.

The down side is you will not find chips in the oil. Any wear has to be detected by movement of the wheel on the bearings and spindle. So jack up your wheels occasionally and measure the movement in and out at the top of the tire. Record that and watch for changes.

Works for me, and that's with over 100k km added to the U1300 since I got it.

Bob
 
#15 ·
I remove the fill plug, insert hose of grease gun, and start pumping. How much? Good question. I put two tubes into each portal. Later I drilled and tapped the fill plug and put a Zerk fitting in it, and use the air-powered grease gun. When I service the truck I take the plugs out, look in, scratch my head, and put in another half a tube of grease. Some grease does make it's way out of the vent tube as the truck is driven. I left it disconnected to watch. Removal of the other fill plug gives pressure relief and lets us know if the portal is full. So far no grease had come out of the other plug.

You all know this is not MB procedure so YMMV, and you take your chances.

Bob
 
#21 · (Edited)
When I service the truck I take the plugs out, look in, scratch my head, and put in another half a tube of grease. Some grease does make it's way out of the vent tube as the truck is driven. I left it disconnected to watch. Removal of the other fill plug gives pressure relief and lets us know if the portal is full. So far no grease had come out of the other plug.

You all know this is not MB procedure so YMMV, and you take your chances.
Interested in the longer term maintenance and service of using the grease versus oil as it may have some advantages as you and others have pointed out. If you are following the MB lubrication schedule (at least for the 435 and I am sure other SBUs), then the lubricant used in the portals should be replaced every 1200 operating hours. Pretty long for most of us. You mentioned you have been using the grease for the last 100,000 km which means you must have replaced the grease at least once if not twice since putting it in. Curious to hear your method for flushing out the portal of the grease (including any wear particulate) before refilling with new, fresh grease.
 
#17 ·
Hmm interesting. I would think the grease would eventually stick to the walls and leave gears dry. But if you pumping it super full then I guess that would work.

Typically though when portals start to leak it's an indicator they are about to come apart. That would be how I knew my lower portal bolts were coming loose and time to tighten them before they catastrophically failed or the portal left the truck. I'd get home, tear it all the way down, re-rtv, lock-tite and be leak free for another couple years or until next major breakage. :wink
 
#19 ·
The main argument for solution is not be to extend the life of worn out parts, but to prolong the period you have for detection of the failed seal. (AMAMOG: seals are cheap and easy to repair; fix them and keep the expensive bits safe.)

A UNIMOG driven on the highway will not make it far if the portal seal fails when filled with oil. NGLI 0 is a good general solution to eliminate this undetectable (at speed) and damaging failure mode. YMMV.

C.
 
#20 ·
Land Rover swivels are not really a good comparison to Unimog hubs. The swivels are really only protecting a UJ or constant velocity joint and providing a bit of splash lubrication. Furthermore in the swivels, grease does not lubricate as well as 90wt. Using grease is a last resort measure because your swivel balls are shot, not because it is a good way to lube the UJ/CV's. The Land Rover "grease" is more like Lucas Hub oil and was used because Land Rover were having constant hub seal failures and it was a short cut fix, not a better lubrication method. Ironically the older Rover hubs (as opposed to swivels) had 90 wt and they lasted forever, the newer grease packed ones not so much. I think if grease was better, Mercedes would have gotten wise to that after 50 years.

As far as using grease to avoid hub leaks. Grease is not going to seal/lubricate the oil seals as well as oil, the seals will probably fail/leak earlier. Instead of oil leaking out, water and contaminants will leak in. Grease does not play well with water or grit. More importantly, grease does not drain...

In S. Sudan I worked on a U1300L hub that had grease in it. It was leaking and was "fixed" with grease a few years back. It was toast when I took it apart, there was a grayish brown muck from water and sand infiltration and obvious rust on parts in addition to scoring. The grease just trapped and congealed the contaminants. How much of the damage was because of the grease and how much was previous damage is hard to say but the other three hubs had 90wt and there were fine other than a little water coming out of one when I drained and replaced the oil. Obviously we couldn't drain and replace the grease quite as easily.
 
#25 ·
Replacing oil with grease in the hubs is a bit tempting idea - my brother's suggested something like that after my truck's hub failure.
I can see some advantages of it - if it works.
But again in my climate, and low temperature viscosity factor I'll stick to the gear oil.
 
#29 ·
One question I forgot to add. Does anyone know if the lubricants used in the corn head grease are compatible with the portal / axle seals? Different lubricants have different additives for various purposes that can make seals shrink, swell, degrade, and so on. We call this oil compatibility and test various manufacturers of oil in very controlled tests with special rubber samples to understand the effects different lubricants might have on a seal. Believe it or not, the same oil from different manufacturers like Torco & Maxima may have completely different outcomes even on the same seal. Not saying it is a problem - but was just curious if anyone had any further info.
 
#30 ·
Hi Moggers If Mercedes thought it was ok to put grease in the portals it would have been there from day one. I have had my Mog for 38 years and replaced many portal seals, so if it was me I would fix the seals and run Castrol Syn Trans oil, bearings run better in oil. Regards to you all and have a good 2016 Aussie Noel
 
#31 ·
I agree with Aussie--MERZ does not rec "grease" in the portals and bearings need to run and lube in gear oil. I have used 80W-140 Synthetic gear oil for years in all my mogs and have never had a problem.
Does not make sense to me. John Deere Picker head grease is just that "picker head grease"!
Not--mog friendly---I dont care what--- experimentation has been done.--- Not acceptable.
There,--- my 66 year old --to the point--- opinion.
TLane
 
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