Allison Transmisson Model MD3000MH

[jimrose]

The 3000 Transmission went into Limp Mode after being in traffic for several hours. Had the Trans checked by Inland Power Group, Carol Stream,IL, (They were originally Detroit Allison before coming under the Inland group.) The finding are all"PSI's" Pressures are low. They recommended Three choices 1.) Over Haul $4800, 6 month warranty, 2.) Rebuilt Trans from Weller (a Allison licensed rebuilder) $6000, 2 yr warranty. 3.) Rebuilt Trans from Allison $7300, 2yr warranty plus tow if required. The RV has 91000 miles and we drive less 10k a year.

May I have some comments on the choices for cost and which one to take. I lean toward #1 because of the small number of miles I drive and cost. I would wait until next April so the warranty would cover 2014 rv season.

[Flamebuster]

Just a thought here, but did they change the trans. cooler after the overhaul?
The Allison shop I deal with will not warranty a trans. unless a new cooler is installed. The reason being the metal particles will stick to the inside of the cooler and all the flushing in the world will not remove it all.Eventually the trans. will fail again from the contamination..
I found this to be true when the Case dealer just flushed the cooler on our loader after rebuilding the Allison transmission. Just something to consider if the trans. is bad...Doug

[RedG]

Tom/Barb wrote:

RedG wrote:
Allison does not recommend ever "flushing" their transmissions. Flushing can do more harm than good.

Do you have a reference for that?

I was about to do mine.

Click here for Allison manual.
See bottom line in graph on page 25.

[cat199]

One other thing on most transmission failures that need a rebuild you will have alot of clutch material in the filters or an excessive amount of metal or both in the filter. If you don't have debris in the filters I would take a oil sample on the transmission and or take to someone else to get a second opinion. No debris in the filter would really make me wonder- if I really have a massive failure.

[docj]

duplicate post

[docj]

Sez Hoo! wrote:
I took my coach to an Allison shop in northern San Diego last year. They did a fluid and filter change and put in Transyn. The told me when I picked it up that I was good for 300k miles. If I were the OP I would do a fluid and filter change first.

Are you aware that if this is the first time you have put Transynd into that transmission it should have been filled and drained and then filled again? That's what Allison specifies in order to ensure that the long-life properties of Transynd are not degraded by the presence of some of the Dexron that it had been filled with.

If your facility did not do a double fill there it does no harm but you should have your fluid tested every year to make sure that the properties don't degrade. Testing is inexpensive and you can do the sampling yourself. After a couple of years you can put new Transynd in and then you should have the 300,000 mile life it is rated at. (Even with that long mileage life, it should be tested annually if you plan on using it for more than 3-4 years.)

[Sez_Hoo_]

I took my coach to an Allison shop in northern San Diego last year. They did a fluid and filter change and put in Transyn. The told me when I picked it up that I was good for 300k miles. If I were the OP I would do a fluid and filter change first.

[docj]

What's unclear is whether or not you or the previous owner switched the transmission over to Transynd. I assume not since there would have been no reason to have changed the fluid as frequently as you have been if you were using Transynd.

If you are using Dexron fluid, the recommended fluid and filter change interval for a 3000 series transmission is 25,000 miles or one year. You've been changing it pretty frequently, but if the previous owner hadn't it's possible no one had changed the fluid or filters for the first 35,000 miles and four years of the vehicle's use. That may have contributed to the problems you currently have. Furthermore, your fluid change interval is roughly correct for mileage but a lot longer time-wise than is recommended for Dexron.

Here's a link to the Allison service schedule: Allison service schedules

[jimrose]

Some further info, We bought the RV April 04 with 24800 miles, Changed fluid and filters June 05 35000 miles, changed fluid/filters Aug 09 73100 miles, changed fluid/filters Sept 12 88246 miles. Present miles 91000. Will call Allison Monday and get their comments.
Thanks for all your comments to date.

[wolfe10]

I concur. While leaving the exhaust brake on all the time will cause accelerated wear for lots more shifting, you are not going to wear out an Allison 3000 by doing that.

But, with exhaust brake on, every time the throttle is closed, the exhaust brake comes on and the transmission downshifts toward the pre-select gear. NO COASTING. So, MPG suffers, and at least for me, it would drive me crazy to have it downshifting and upshifting several gears on each down/up hill.

[docj]

rocmoc wrote:

jimrose wrote:
Just a little more clarification, The tran went into safe mode three times in the last two times we were out. Also I leave the exhaust brake on all the time. The last time for safe was after coming down several blocks of a steep hill at slow speed with the tran in 2nd. I will call shop Monday to see if the ECM was rebooted. Thanks for all the thoughts so far.

This isn't the first time I have heard this. The previous owner of our Rig also drove everywhere with the exhaust brake on and burned the tranny up by 45,000 miles. He was told by the repair shop NEVER to leave the exhaust brake on, just when you need to slow down or stop. When we bought the rig it had under 50,000 miles on it with less than 5,000 miles on the newly rebuilt tranny (have the invoice where he paid $5,000). We now have over 60,000 miles on the rebuild / 5 years without any problems. AND we have pulled some HUGE grades & loads in very remote locations. I would still try what others have said as you nothing to lose but a lot to gain. Good luck!

rocmoc n AZ/Mexico

IMHO this doesn't make any sense. An exhaust brake or a compression brake isn't doing anything UNLESS you are slowing down or stopping. Having it on when you are cruising on the highway shouldn't have any effect on the transmission until you let up on the pedal.

I can see someone arguing that the repeated downshifting that occurs could cause transmission wear but I'd be rather surprised if many motorhome owners drive their vehicles enough for this to be an issue. Remember these transmissions are designed for buses, garbage trucks, etc, vehicles that run all day upshifting, downshifting and idling.

[rocmoc]

jimrose wrote:
Just a little more clarification, The tran went into safe mode three times in the last two times we were out. Also I leave the exhaust brake on all the time. The last time for safe was after coming down several blocks of a steep hill at slow speed with the tran in 2nd. I will call shop Monday to see if the ECM was rebooted. Thanks for all the thoughts so far.

This isn't the first time I have heard this. The previous owner of our Rig also drove everywhere with the exhaust brake on and burned the tranny up by 45,000 miles. He was told by the repair shop NEVER to leave the exhaust brake on, just when you need to slow down or stop. When we bought the rig it had under 50,000 miles on it with less than 5,000 miles on the newly rebuilt tranny (have the invoice where he paid $5,000). We now have over 60,000 miles on the rebuild / 5 years without any problems. AND we have pulled some HUGE grades & loads in very remote locations. I would still try what others have said as you nothing to lose but a lot to gain. Good luck!

rocmoc n AZ/Mexico

[Tom_Barb]

RedG wrote:
Allison does not recommend ever "flushing" their transmissions. Flushing can do more harm than good.

Do you have a reference for that?

I was about to do mine.

[docj]

RedG wrote:
If your Allison has never been serviced in 91000 miles, I wouldn't be surprised if that's your problem.

Has your transmission been serviced previously? A '01 model would probably not have had Transynd originally. Did you or anyone change it over to Transynd? I hope you haven't been running Dexron for 91,000 miles without servicing it.

[dons2346]

I, for sure, would contact Allison before doing any "rebuilding".