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Kota 05-02-2015 02:01 PM

Allison MD3060 Fluid/Filter Change
First, it's a pretty simple procedure and their are a bunch of posts and YouTube videos on the topic. I spend countless hours stuck in hotel rooms with my job and over research these things to kill time. There a few things to be aware of so I thought I'd share.

First, be very careful not to introduce dirt into the system. You will probable be at least as careful as the "professionals". Power wash or at least clean the bottom of the transmission. Work on a clean surface.

The bottom of the transmission is not an oil pan. It's the controls module and its heavy. You don't want to remove it. There are two round covers that are held on by 6 bolts each. They do not drain the oil. They are removed to replace the filters. You will loose a quart or so when they are removed.

The drain plug is opposite them on the bottom. It's removed with a 3/8" ratchet stuck in the square hole. It will drain about 4 1/2 gallons. A 5 gallon plastic bucket will not fit under it unless you jack up the coach. Two 3 gallon buckets worth nicely. Be ready to slide the next one in as the first gets full. I like to start with clean white bucket so I can examine the fluid and fill a sample bottle.

The best deal I found on genuine Allison filters was at Transwest Truck Parts. About $65 for the kit. There are complete instructions in the kit along with o rings and seals for two different configuration. Somewhere around 98 they switched from a square cut seal ring to a large o ring and gasket. Put the right set in based on the serial number range specified in the instructions.

Torque them as specified! You can strip them. The covers should pop up completely in place with the palm of your hand. Don't draw them up with the bolts or you will be hating life. Use a cross pattern to tighten them in steps. This in in the instructions.

There is also a new ring for the drain plug. It's torque spec is much less than you might expect. Be careful! Use a 3/8" torque wrench.

You can read for hours about fluids. Transwest has Transyn on the shelve for $45 a gallon. The 4" sump version takes about 5 gallons. The filters for the 4" sump are about 6" long.

The transmission originally came with Dextron 2. The new Dextron "compliant" fluids are not compatible with the seals in our vintage Allison and can cause them to fail. That goes for some of the new snake oil additives also. Call Allison if you have any questions.

Make sure the area around the dip stick is clean. Important when you check the fluid level also. These rear engine units tend to get pretty dusty. A 3/4" OD clear hose works well to fill through the dip stick tube. Set the jug on a ladder or hang it and start a syphon.

Allison doesn't recommend any type of power flush due to the potential of damaging seals. There will be an amount of fluid trapped in the torque converter. They seem to just accept that. If the fluid smelled burnt or was badly discolored, I'd call Allison. You will probably need more than an fluid change anyway.

That's it.

Kota 05-02-2015 02:06 PM

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Kota 05-02-2015 02:08 PM

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wxbuoy 05-02-2015 03:40 PM

Thanks! I need to tackle that project as well!!!

Kota 05-06-2015 09:55 AM

Allison MD3060 Fluid/Filter Change
2 Attachment(s)
Step 1

When I inspected this vehicle there was sludge on the bottom of the dipstick. I'm first priority was to service the transmission. The filters looked good, no sludge in the bottom of a clean drain bucket, and the fluid looked and smelled ok.

After service I had sludge on the bottom of the dipstick again. WTF!

Any moisture that cooks out of the transmission after sitting collects in the dipstick tube and create corrosion and sludge. Further proof that moisture from sitting is a bigger issue on these rigs than milage. Only 32k miles on a 20-30 year old rig might not be as significant as used regularly.

Attachment 237887

Attachment 237888

You can see the where the dipstick scrapes the side of the sludge in the tube!

The tube is fairly easy to remove and clean. Should have been the first step before dumping $250 worth of Transyn through it.

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