Rear seal leak on Cummins and need to pull Allison MD3060

Even if you buy that over priced seal and that over priced seal driver- you would still save $1000 doing it your self.
I made up a driver for the trans output seal on my Allison and the differential seal that was leaking. For $441, I'm sure I could make a seal driver for that rear engine seal.
It all comes down to how much you like your money and how much you want to do.

Mike Hohnstein wrote:
I wonder if any of the posters but me have changed a rear main seal on a medium duty diesel engine. Experience speaks volumes, other views not so much.

What he said. A lot of things look good on paper.

I wonder if any of the posters but me have changed a rear main seal on a medium duty diesel engine. Experience speaks volumes, other views not so much.

srukke wrote:
I'll start by saying I am very mechanical, rebuild engines pull and install engines, trannies etc.
But my RV has an Allison MD3060 behind, rather in front of, a Cummins 230hp on a Winnebago pusher. 1993. Great running rig with a rear seal that leaks on the Cummins. The MD3060 is big. Anyone know the weight? Is this doable with a couple guys and a tranny jack? The job seems simple enough it's just the sheer size that gives me pause. Anyone done it and have advise? If I do trannies I usually replace the front tranny seal while it's out. Is that something I would want to do here too? Any specialized equipment other than a heavy tranny lift that's needed?

srukke,
Well Sir, first off I applaud you for even thinking about doing a job like this yourself. Based on your reported resume, it sounds as if you'd have no problem doing it. Yep, I know the size of some of this stuff can be intimidating but, in most cases of repairs on these rolling Kleenex boxes, it is ONLY size that's different.

You see, back a while ago, I had a left rear axle seal leak on our '04 Itasca Horizon 36GD with the C-7 330 CAT. I'd seen the same types of axles out a zillion times before, while working overtime assignments in our Fire Dept. repair facility. I figured, what the heck, let's do it. So, I jumped in with both feet.

And, as expected, pulling that axle was almost identical to pulling one on a 3/4 ton pickup. Replacing the seal, was also almost identical with the exception that, it was considerably LARGER than a pickup axle seal. So, I improvised. I made a seal installer. It worked flawless.

My point, as one poster above me stated, just get the correct tools/jacks etc. and you'll be probably $1700 ahead of the game after purchasing the seal and, renting the correct tools. Heck, if I were closer, I'd dive in there with you and I'm getting too old for this stuff. To me, some of this stuff is actually still fun to do. I just helped a buddy replace a front wheel seal on his '06 Itasca Meridian 34H. The technical side was almost identical to the rear seal replacement on mine. Piece of cake.
Scott

First off, the weight of the transmission is a non-issue. Also getting the RV up high enough to get the transmission out from underneath is not necessary. I have dropped several transmissions to work on the engine itself and in most cases, all I had to do was move the transmission slightly out of the way to allow me to work on the rear of the engine. The transmission jack that I use, is not a large one, but it is on wheels and has a 1200 pound capacity. This is more than enough for your transmission. Basically all you have to do is put the jack under the transmission and lower it enough to allow you to roll it back a few inches to allow you to replace the rear seal. Once the seal is replaced, you just roll it forward, raise it, and reattach the transmission. Depending on how the engine is supported, you may have to put a bottle jack or two under the engine when the transmission is removed.

clicky

Tools required


There's a reason for prices quoted for heavy work. Not dealing with small block gas engine here. Screw up the installation of a diesel rear main by trying to beat it in with a drift will not make your day.
It gets down to how much you value your time vs. the value of your money.

There is a guy on IRV2 forum that pulled his trans for a rebuild.
He used the jacks and an 8 x 8" to raise the MH up high enough to get the trans out. It didn't look that hard actually- drop the drive shaft and then unbolt the trans and slide it back to get at the converter bolts and after that- drop the trans out with a HD trans jack.
There is a guy on eBay selling an improved "leak proof" rear seal for the 5.9B and that seems simple to replace.
If $1900 seems excessive to you(I think so too) then You can do it your self and I will do mine when and if it starts leaking.
Google "replacing the allison MD3060 trans".

I already put 3 or 4 cans of the tranny sealer in it. Made no difference. Hoping I can find a more reasonable shop to fix it. Thanks everyone for the suggestions.

You might want to consider putting some transmission sealer into the oil on that Cummins. It might swell up that rear main seal and slow and maybe even seal up that drip. The stuff that Walmart(Trans-go?) has really works. Put a couple of cans of that into the oil.

Thanks everyone. It is probably too big of a job for me. I just have a hard time with the $1,900 quoted by a local truck shop. Seems excessive for a drippy seal. I will keep looking.