Gear oil coming out vent lines

[mdes0]

Hey folks, recently replaced my rear diff with an ARB unit and since that time I've been getting gear oil in the air cleaner. Several months ago I had replaced the front diff with an ARB when it torpedoed and had no issues, other than a leaky output shaft seal that I haven't replaced yet. I've confirmed that the gear oil is still getting blown out the vent lines when not using the lockers so it has nothing to do with air pressure from the locking mechanism.

Anyone run into something like this when using diffs other than the standard torsens?

Matt

 

[rcamacho]

Had this issue on one other vehicle (not an hmmwv). The diff was slightly overfilled.


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[Dock Rocker]

Could be coming from the hubs to.


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[gsp45]

Why not contact ARB its their unit.

 

[MarkM]

You sure it is not gear oil mixed with ATF? I had this happen and it turned out to be the dreaded Vampire leak. The cooler in the transfer case develops a leak so the tranny pumps ATF into the transfer case and then out the breather lines to the pumpkins and Portal hubs and onto the air cleaner. Easiest way to find out is checking your tranny fluid level to see if it is low and go from there. Just a thought.

Mark

 

[AOR]

Often with the ARB lockers in various applications need additional oil drainage areas machined or drilled into the differential. We have seen the oil make its way back to the compressors. Also if the oil if overfilled on any differential it can make its way out of the vent lines
I suggest contacting ARB tech support and see what they have to say. 888 427-2872‬.

 

[mdes0]

Took your advice and called ARB. I had read about some Dana diffs needing an oil drain slot added. They told me they hadn't heard of any issues with the Humvee diff, which as you probably know is an AMC 20. They are doing some more digging for me. In the mean time I'm going to put the hubs and diffs on their own vent line so I don't risk getting gear oil in the trans and tcase.

 

[AOR]

Glad you called them. I know for a fact the Diffs in my 1986 are made by Dana the covers have the Dana logo on them so maybe there are multiple diff manufactures out there that made the diffs for these. you may want to get the numbers off of the ring gear and see what google comes up with or look for the Dana logo on them
I had asked Kascar who made the diffs for these and they thought they were made by Dana specifically for the HMMWV

 

[AOR]

So I took a look again at my diffs both have the Dana emblem and read DANA on the covers but the housing does look similar to the AMC20 the Jeep CJ's used. I also noticed my rear is supposed to be 2.56 and the front is 2.73 since I have no binding I am assuming the tag on one of them is wrong guess I will be pulling my covers
I am going to include pictures showing the DANA emblems on both covers

 

[AOR]

I just found out from a reliable source that said Dana made the AMC 20 differential which I was not aware of

 

[WAGNUM]

Matt- I just had ARB 187 lockers installed in my AMC 20 diff also. I'm having the exact same issue you are on my rear diff. Any advice?

 

[WAGNUM]

What I learned: The ARB locker and shims sit close to the journal bearings not allowing gear oil to drain back quickly enough into the main housing area of the diff. Has nothing to do with the locker operation. When driving it pumps oil in between the journal and stub shaft bearings, can’t drain back fast enough, builds pressure and pumps out vent tube. Fix: holes will have to be drilling inside the housing to create drain passages. I read that Jeep guys with solid axel AMC 20’s have same problem and ground drainage slots to solve problem. ARB didn’t have an answer so if this theory works hopefully ARB can update their install instructions specifically for HMMWV’s. (I’m out of breath...)

 

[Action]

Matt- I just had ARB 187 lockers installed in my AMC 20 diff also. I'm having the exact same issue you are on my rear diff. Any advice?

What about giving the diffs their own vent lines, not hooked to any other components?

 

[mdes0]

Hey Wagnum, sorry and kinda of relieved that you ran into the same issue. I found the same info on the solid axle AMCbut was hoping I could avoid having to make any sort of drain or channel. Had the same results with ARB, no help to date. I haven't made any changes to the diff yet. What I have done is run a new vent live for the trans and t-case to the air box to avoid any future cross contamination. I also moved the rear diff vent line to an empty plastic water bottle, I know big time red neck fix... I put a quick connect vent filter on the end to provide some resistance. I put a whole just large enough for the vent line in the bottle cap and hung the bottle upside down in the rear passengers wheel well. When it accumulates fluid I drain it out. I have noticed that when I park after driving for a good amount of pressure, air and a bit of fluid, can be heard blowing into the bottle. I also found that my rear portals were both FULL! Also had one front that was high, that might be from the front diff as that is ARB Also. My rear diff is now making a clucking noise so I have to drop it out again and take a look. Not sure if the pressure buildup is causing the diff to partially lock or what. Will let you know. I have also pulled the cover and changed the fluid and all looked good...

I also swapped both axles out for a new pair. Did find an outer that was bone dry and the boots were pretty dry rotted. I used axles from parts-liquidator on ebay, they use junk boots that leak... I ended up having to replace all the boots to get the grease to stop leaking out. They did refund me some money but was not worth the amount I saved. Especially since I torn my bicep tendon during one of the replacements.

 

[WAGNUM]

Matt,

So I pulled my diffs out again (8th time this summer, grrr...) and taking them to my guy this afternoon. He will drill relief holes under the carrier bearing seats to allow the oil to drain back into the main case. Apparently, Jeep AMC 20's diffs already come with relief grooves in them for this exact issue. I'll take pictures and post them asap.
So I had the same thing happen to me: Diff pumped gear oil into my hubs and overpressurized them, pushed out the half shaft seals and made a uge mess.

Funny you mention the overflow bottle cause I did the same thing with a chocolate milk bottle. Drive for an hour and about 6oz of gear oil pumped out. I was thinking a poor man's fix could be to route the vent line to a barbed fitting that would screw into the fill plug on the cover. It would just cycle oil back into the case. Then drill and tap a new vent on the top of the case... This is prob a dumb idea cause you'd still need to drain and pull the cover off to catch all the shavings when drilling and tapping the new vent line.

Anyway, I'm hoping we can get the flange seals out without damaging them, but I doubt it. O well, I got new ones coming from HPG so whatever...

I mentioned drilling and tapping an additional vent in the top of the case but my guy thinks its overkill and the relief holes will be enough. I sure hope so...

 

[WAGNUM]

Sucks about the tendon, takes forever to heal. Be very careful where you buy half shafts. There is a huge batch of GSP H1 Rear Half shafts that are being sold that are too long. I even had them contact the warehouse in CHYNA! The warehouse was like "oh yeah you're right they're too long. But we're not gunna do anything about it." So that's fun...

Hey Wagnum, sorry and kinda of relieved that you ran into the same issue. I found the same info on the solid axle AMCbut was hoping I could avoid having to make any sort of drain or channel. Had the same results with ARB, no help to date. I haven't made any changes to the diff yet. What I have done is run a new vent live for the trans and t-case to the air box to avoid any future cross contamination. I also moved the rear diff vent line to an empty plastic water bottle, I know big time red neck fix... I put a quick connect vent filter on the end to provide some resistance. I put a whole just large enough for the vent line in the bottle cap and hung the bottle upside down in the rear passengers wheel well. When it accumulates fluid I drain it out. I have noticed that when I park after driving for a good amount of pressure, air and a bit of fluid, can be heard blowing into the bottle. I also found that my rear portals were both FULL! Also had one front that was high, that might be from the front diff as that is ARB Also. My rear diff is now making a clucking noise so I have to drop it out again and take a look. Not sure if the pressure buildup is causing the diff to partially lock or what. Will let you know. I have also pulled the cover and changed the fluid and all looked good...

I also swapped both axles out for a new pair. Did find an outer that was bone dry and the boots were pretty dry rotted. I used axles from parts-liquidator on ebay, they use junk boots that leak... I ended up having to replace all the boots to get the grease to stop leaking out. They did refund me some money but was not worth the amount I saved. Especially since I torn my bicep tendon during one of the replacements.

 

[WAGNUM]

Here's the fix: My installer Leonard, drilled a 1/4" hole at a 22.5-degree angle upwards in through the bottom right "fixture hole" (To clarify: These holes are not "case spreader" holes. A case spreader with ruin your diff because it's aluminum so don't use one) The pictures above should give you a good idea of the angle. It's important to drill upwards and inwards so that you access the cavity between the two bearings (about a 1" wide space). Drilling upwards means the hole will be above the level of the bearing's rollers, so enough oil will be left to create an oil bath for the stub shaft bearing. If the hole is drilled too low (or level), the gear oil will just drain out and not lubricate that bearing. The diff cover seals on the outside of the drilled hole allowing the gear oil in that cavity to drain back into the main case preventing overpressure and hopefully no longer pumping gear oil up and out of the breather vent line. The drilled hole is 1/4" and the diff vent line hole is 1/8", I'm hoping this means the gear oil will have more than enough room to flow back into the case. When drilling, you're only drilling through about an inch or less of the case so go "slow." Going slow allows for the bit to grab large shaving and you avoid making small glitter that could get into the cavity. Start with a small bit for your pilot hole, then use the 1/4" bit. Leonard is a pro and assured me he could drill this without contaminating the cavity so we did not pull the seal and stub shaft out. I watched him drill slowly and he kept the bit moving when it drill through. I'd also blow on the vent line while drilling / cleaning to pressurize the cavity and keep shavings out. Seems like a simple fix but you'd better make sure you're drilling the hole in the correct spot. Not a lot of room for failure. I'm waiting on other parts but should have my HMMWV up and running in 2 weeks. I'll follow up soon, good or bad. I'm also sending this info to ARB (I hope they appreciate it...) so the next guy down the line doesn't get screwed.

 

[mdes0]

Any update after drilling the case?
Thanks,
Matt

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Here's the fix: My installer Leonard, drilled a 1/4" hole at a 22.5-degree angle upwards in through the bottom right "fixture hole" (To clarify: These holes are not "case spreader" holes. A case spreader with ruin your diff because it's aluminum so don't use one) The pictures above should give you a good idea of the angle. It's important to drill upwards and inwards so that you access the cavity between the two bearings (about a 1" wide space). Drilling upwards means the hole will be above the level of the bearing's rollers, so enough oil will be left to create an oil bath for the stub shaft bearing. If the hole is drilled too low (or level), the gear oil will just drain out and not lubricate that bearing. The diff cover seals on the outside of the drilled hole allowing the gear oil in that cavity to drain back into the main case preventing overpressure and hopefully no longer pumping gear oil up and out of the breather vent line. The drilled hole is 1/4" and the diff vent line hole is 1/8", I'm hoping this means the gear oil will have more than enough room to flow back into the case. When drilling, you're only drilling through about an inch or less of the case so go "slow." Going slow allows for the bit to grab large shaving and you avoid making small glitter that could get into the cavity. Start with a small bit for your pilot hole, then use the 1/4" bit. Leonard is a pro and assured me he could drill this without contaminating the cavity so we did not pull the seal and stub shaft out. I watched him drill slowly and he kept the bit moving when it drill through. I'd also blow on the vent line while drilling / cleaning to pressurize the cavity and keep shavings out. Seems like a simple fix but you'd better make sure you're drilling the hole in the correct spot. Not a lot of room for failure. I'm waiting on other parts but should have my HMMWV up and running in 2 weeks. I'll follow up soon, good or bad. I'm also sending this info to ARB (I hope they appreciate it...) so the next guy down the line doesn't get screwed.

 

[WAGNUM]

UPDATE:

Took my HMMWV out last weekend. Drove 5.5 hours from Portland out to Christmas Valley and played on the trails and sand dunes for 4 days. The Air Lockers worked flawlessly and not a drop of gear oil out of the vent lines. I kept my homemade catch cans on the diffs so I could monitor and they were dry all weekend, there and back. I’m very pleased with the fix that Leonard performed and I hope my experience helps someone else that wants to go the ARB Air Locker route.