Broke Down! Need help with Allison MT 647

oldmansax · August 17, 2017, 01:12:47 PM

I have an Allison MT 647 Mechanical behind a 3208 Cat. It has been shifting fine. I drove it about an hour and a half this morning to a campground. It did not want to shift into 1st when I stopped to check in. I revved it up a little and got to the campsite. Now it won't shift in to 1st at all. It shifts into reverse fine. I did notice the trans temp ran about 245 which was higher (I think it has been running about 220 but it is hot here today) than it has been. The fluid is on the full mark. It SEEMS to smell a little burnt but not much and that may be my imagination. I'm getting paranoid!

Any suggestions? Ideas?

Thanks!

TOM

ol713 · August 17, 2017, 02:57:22 PM

Hi;
Can you tell us what part of the country you are in? Maybe help is close by.
Merle.

oldmansax · August 17, 2017, 04:36:17 PM

Eastern Shore of Virginia. Little town called Temparenceville. There are aurthorised Allison shops in Salisbury, MD which is not that far away but I am hoping I can drive and not have to be towed.

Also, cell service is awful. I can get texts but that seems to be all.

four four three 52 won seven seven 6 ate

TOM

luvrbus · August 17, 2017, 04:38:01 PM

You have low main pressure Tom ? do you know how to check the pressure by removing the plug and installing a gauge

oldmansax · August 17, 2017, 05:12:31 PM

Clifford, no I don't and I only have minimal tools with me. I haven't had any mechanical troubles with this coach and was only going a couple hundred miles so I thought I could get away without a bunch of tools. That's what I get for thinking! I don't have a gauge either. However, would I still have good reverse with low pressure?

TOM

luvrbus · August 17, 2017, 05:36:33 PM

Yep it only affects the foward low gear

oldmansax · August 17, 2017, 05:46:41 PM

Thanks for the info!

Any thing I can do about it to limp home? If I rev engine is it possible to get it to shift to 2nd without major problems. If I have to go into the trans, it will have to either drive to my shop about 50 miles or be towed. If I have to get it towed I just as well call them tomorrow morning.
TOM

oldmansax · August 17, 2017, 05:49:07 PM

FYI, flat ground all the way. Need to at least get out of the campground. It will be a nightmare getting a wrecker in here.

TOM

Zephod · August 17, 2017, 06:44:57 PM

http://allisonparts.net/Allison-Transmission-Parts-Tips.html

That might help

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oldmansax · August 17, 2017, 07:11:45 PM

Quote from: Zephod on August 17, 2017, 06:44:57 PM
http://allisonparts.net/Allison-Transmission-Parts-Tips.html

That might help
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Thanks for the link! I guess I will just see If I can get it to move tomorrow morning. Hopefully I can get it somewhere to rebuild the valve body if that is the problem. I'm still hoping for a temporary magic fix! LOL!

luvrbus · August 17, 2017, 09:08:42 PM

I hope it is a easy fix too Tom but the smell of burnt oil is not a good sign,245 is a little warm they run between 180 and 220.They can tell in few minutes with a pressure test where the problem is.If I was closer I would help you and it would only cost you crab-cakes

Lin · August 17, 2017, 10:25:03 PM

when was the last time the filters and oil were changed?

oldmansax · August 18, 2017, 04:26:34 AM

Quote from: luvrbus on August 17, 2017, 09:08:42 PM
I hope it is a easy fix too Tom but the smell of burnt oil is not a good sign,245 is a little warm they run between 180 and 220.They can tell in few minutes with a pressure test where the problem is.If I was closer I would help you and it would only cost you crab-cakes

I know you would help if you were closer and I not only appreciate that but all the help you (and the rest of the guys on here) have been. If you were closer I would buy the crabs cakes anyway....help or no. LOL! Once I get to the shop I will get the manual and pressure test it. I just didn't think I was gonna need hard core tools for a short run.

Last question (maybe): It never did stop moving completely, meaning I can rev it up and move in 1st. Any chance I can get it going fast enough to shift into 2nd? Maybe get back to my shop (50 miles)?

Lin: Supposedly all fluids and filters were changed when I bought it. I have put less than 5000 miles on it. I was gonna change it anyway this fall when I do seasonal maintenance. Would filters cause this?

Thanks!!!!

TOM

Branderson · August 18, 2017, 06:17:44 AM

I'm curious about the burnt smell of fluid. Does that normally only mean burnt fluid b/c it got too hot or does it typically mean a catastrophic break down of the transmission.

thomasinnv · August 18, 2017, 08:00:39 AM

Quote from: Branderson on August 18, 2017, 06:17:44 AM
I'm curious about the burnt smell of fluid. Does that normally only mean burnt fluid b/c it got too hot or does it typically mean a catastrophic break down of the transmission.

It has been my experience that once you see/smell burnt fluid it is usually too late. Damage done.

Was it just a faint hint of a burnt smell? Or was it a strong obvious odor and color? With only 5k on the oil and filter and being burnt would not give me a positive feeling, especially with the high temps.

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