Foretravel recommends this yearly but that might be way overkill. I did this yesterday. Drained about 3.75 gallons. Now onto the front hubs.
Tools needed;
Oil catching container of at least 10 gallons
1. Four (4) five (5) quart empty oil jugs that are marked at the quart level.
2. One clean 5 qt empty oil container to pour new fluid into from 5 gallon pail and also to get up under coach to pour the fluid into the funnel.
3. This is to measure the amount of oil that is taken out.
4. A small one quart open container to pour the oil from the large catching container into the empty oil jugs.
5. A tarp to lay on ground in case you spill some
6. rags and paper towels.
7. a funnel with a ¾ " inside diameter extension hose about 10 " long
8. Rubber gloves
9. ½" drive ratchet to remove drain plugs
10. Drop light
Warm up the rear axle oil by taking the coach for a ½ - 1 hr drive. The capacity if the rear axle is 4 gallons so use a large enough container to catch the fluid.
1. Park on level ground
2. Raise rear of coach as high as possible and place safety frame spacers into coach frame in case of air pressure loss.
3. Safety chock the vehicle.
4. Put tarp down
5. Slide large oil catch container under rear axle
6. Unscrew the drain plug
7. When drained reinstall drain plug
8. Scoop the oil from the large container into the empty 5 quart containers and fill to the 4 qt mark
9. Clean the area around the fill hole
10. remove the fill plug on the rear of the housing.
11. Put hose extension into the fill hole
12. Fill to maunfacturers recommended level
13. reinstall fill plug
14. Take coach for a spin and recheck fluid level after cool down
Rick,
Nice explanation, and a job well done. No scraped knuckles? I always forget the gloves... :o
Two minor suggestions:
Remove the fill plug FIRST. Two reasons. If it is seized and you can't remove it, you now have a BIG problem. Second, it allows a smoother fluid drain, as there is a source of air and the drain hole doesn't have to "burb".
And if you determine the amount of oil to be added strictly from how much you drain, you are ASSUMING that the original oil level was perfect. Better to fill it to the proper level per axle manufacturer's instructions. I know Rockwell (now Meritor) has excellent service information on-line. In fact, just accessed this to look up the correct front axle king pin draw key torque for a 941 front axle (U320).
Brett Wolfe
Rick,
Just one minor add. Synthetic oil is VERY SLIPPERY, even with gloves. Be very careful handling open containers, especially over your head. Don't ask me how I know.
Dave,
Good suggestion on checking that the rear axle vent is clear. And, like "the other" Brett, I use synthetic gear lube in the front and rear axles.
The draw keys, which are basically wedges that hold the king pins in the axle, (2 per side) on the Rockwell/Meritor axle are not a normal maintenance item, but, over the years of checking coaches, I have found several that were finger tight. That allows the king pin to move around in the axle which leads to rapid wear.
Is this something that needs to be check annually-- no. Is this something that you might want to check some time where you are under there lubing the front end (with the wheels off the ground)-- yes.
Brett Wolfe
Peter,
No scraped knuckles this time. On the glove thing, I put on a pair of mechanics gloves first and then put on a pair of large rubber gloves over them when draining any hot fluids. The drain plugs are usually HOT and when pulling the plug away or dropping it in the pan is done you inevitably get hit with some hot oil and the underlying mechanics gloves insulate against that hot oil.
Brett W,
Interesting comment about removing the fill plug first. I have never had one that was seized but I suppose it could happen. If the oil "burps" out then you might have a plugged vent. Just pulling the drain plug will test the vent. When the drain is opened you will hear the vent allowing air in.
I had checked the fluid before draining so I knew where it was. Also I filled it with about the same amount drained as a start point and then topped it off slightly to get it to the proper fill level, (bottom of fill plug) less informed individuals may not get that right. Kind of like the Caterpillar engine dip stick thing. I edit the post to reflect "fill to proper level in accordance with manufactures instructions"
I'm going to take a look at those king pin bolts when I get to greasing next week.
How much oil do the front hubs take? I will get to that this week.
Brett H.
Yes it is slippery, notice the "tarp" shown as one of the required tools. The tarp has become standard equipment for me as as it also keeps from losing as many tools. This particular oil smells funny too. Thanks for the "heads" up. OK, I won't ask but I have a good idea. You do have to get up under there and pour the oil from the 5 qt container. The only slight spill I had was when I got too greedy and filled up the funnel a little too fast and it spilled a bit. Although not like straight weight 140, it still flows a bit slow at 50F.
A quart will do both sides with plenty left. Actually, I usually drain old, fill, run a few miles and drain and refill again since most of the time is spent accessing the hub. Particularly recommend the double change if changing to synthetic gear lube.
Brett Wolfe
Is anyone familiar with how to service the rear axle on our 99 u320....the reference to (fill from axle as opposed to the differential has me puzzled....Thanks....d
If you are refering to checking the lube level in the differental you will remove the plug that will be located about half way up the differental housing, not the plug on very bottom as it is for draining. After removing, stick your finger in the hole to the first joint and if you touch lube the level is good, if not add lube in the same hole until you can touch it with the first joint of finger.
Try going to rvcruzer.com. (http://rvcruzer.com.) It's a good site.
Go down left side of page under misc RV page, click on how to service and maintain your diesel RV . Site is for Tiffin, Allegro owners but has a lot of good info.
Joe
Dave,
It is the Axle "housing" that they are referring to, as opposed to the differential (or "carrier") which is the part that carries/holds all of the gears and is bolted to the axle housing. The picture shows the axle housing with the fill plug. I did a brief write up here on changing the diff oil a couple of months ago.
http://www.foreforums.com/index.php?topic=11038.msg53754#msg53754 (http://www.foreforums.com/index.php?topic=11038.msg53754#msg53754)
Good luck,
Thank you, the distinction on the axle housing helped me see the light.....
Changed rear axle fluid today. (Unusually nice weather here in NM made the job easy.) I had read all the notes under this topic and the instructions to prepare myself. I made some modifications, as I had purchased fluid in 1 gallon containers and had a special cap and an eight inch drain hose (from oil drain kit purchased years ago) to use. There is plenty of room under our coaches for doing this job when raised to full height. The square Rockwell axle made for an easy perch to rest the gallon jugs on as they drained into the axle. (I punched a small hole in the top portion of each jug to assist with gravity drain....
I emptied and cleaned the front hubs while waiting for the gallon jugs to drain into the rear axle. With the information about this job being well presented, I found it easy to accomplish. And the drain plug even had a magnet in it, so that after wiping the plug clean, it could be stuck onto the axle near the drain hole and not get lost.... Again, thanks to everyone for their knowledge and sharing.
Andy1