Extreme Transmission Leak

[makemineatwostroke]

bcaddell;A little advice you can take with a grain of salt the 654 is a very hard transmission to work on in the vehicle and require so many special tools,it is not that great a transmission for the weight ratio of your bus that is why it is a 5 speed they work great in a MCI 5.Me I would buy a takeout 740 and replace it the only parts you would need is the flex plate and a possible drive line modification,you will see 740's on these boards for 1000 bucks up to 2500 look on the BNO add there was a couple for sale.You can get your money back on the 654 and the parts from somebody with s MCI 5 looking to convert it to auto because parts are expensive and hard to find for that conversion  plus the 740 is about bullet proof.   

How these guys can tell a re builder assembled it wrong or installed used parts from a photo is beyond me but if you are worried about pressure buy a grease gun hose and a 250# gauge and remove the test plug using your guide in the manual check the pressure at the rear and the front it may have too much from valves sticking  it does not take a PHD to do that, all that said you would be happy with the 740 vs 654

[busshawg]

Now for my 2 cents worth
If you are going to try it yourselve, I would definitly try the gasket first, as you said it has been sitting. I know of friends of mine who have bought big rigs from customs and have all kinds of leakers because the units have been sitting, even some late models. If it doesn't work I tend to think it may be the flex plate. A faulty flex plate can cause this under load.  If you have the time , that would be the biggest expense. If it doesn't work we'll your back at the shop and at least you tried.

Good luck

[Busted Knuckle]

bcadel,
I apologize for stealing you thread! I just can not stand to see anyone get hurt because of a wannabe!
Have a good day & Good luck on the repair!    BK 

[bcaddel]

Busted Knuckle
I understand your frustrations with certain posters but my experience is they just want attention and to stir people up. When everyone ignores them they always go away. I do agree with you that someone could really get themselves into a situation they would regret if they followed his recommendations but I think most everyone can tell the difference from people like yourself and several others with real knowledge and experience and from the goofballs that try and give advice but cant even write a coherent sentance.

Personally I am very appreciative for all the suggestions and comments I have received. We have ordered the parts necessary to replace the leaking gasket and get the bus roadworthy. I understand that most of the 40 ft buses use the 700 series Allisons as makemineatwostroke mentioned (thanks 2stroke), but what problems should I expect from the MT 654 that I currently have. It seems to be very smooth and works flawlesslly in the 12,000 miles it has on it according to my dad and in my short time with it. If the repair of the leak holds should I consider looking for one? A used one is all I could afford and I am concerned I could be jumping from the frying pan into the fire with a used transmission.

[makemineatwostroke]

bcaddell; the 654 is a better transmission than the 644 having the low gear to start your bus.I wasn't clear but when you start your repairs if the 654 has major problems the 740 would be a better choice than a rebuild on the 654 a plus would be if you ever do a engine upgrade the 654 will have to go anyway.The 654 will give you good service just do the maintenance as required.  have a great day and good luck

[circusboy90210]

knew that was probably what it was .that's why  ;DI said that. it's not simple but it's not rocket science ether though(e experimental physics).I was taking a stab in the dark2 test my confidence this had nothing 2 do with getting any one hurt.(I don't shop Harbor Freight china crap.) if you take a clowns advice, well. anyways even if you buy the" right" tools your better off in the long run. most mechanics Will tell you otherwise, or that it's too complicated 4 the average .person but if you can think things through & know how to read you can do most anything. this site is supposed to empower folks, nobody should discourage diy as this site is 2 inform how 2diy.how ever if anyone has taken this as a slight I apologize but I'm not wrong bout concepts.  

[makemineatwostroke]

clown; the guy is not going into this blind if you read his post his son-law has experience and the tools to do this job something the average guy doesn't have. If he does have problem someone here will try and help                     have a great day

[bcaddel]

makemineatwostroke
Thanks for all your valuable input, I did some looking for a 740 and found a couple for $2,500 but they were used and no guarantees. My bus weighs 35,000 with full fuel, water and supplies. Do you think the 654 is strong enough for that weight?

We live in Reno Nevada and do quite a bit of mountain driving. It seemed to do a really good job prior to the leak and still seems to do just fine as long as it has fluid. My son-in-law said he will also order a transmission temperature gauge so I can monitor the temp of the transmission, if the temp stayed within range and it is shifting smoothly do you think I can assume the 654 is adequate.

The last think I want is to break down somewhere because of something I could have prevented.

[makemineatwostroke]

bcaddell,as long as you have the 8v71 for power you will be allright it is the torque that hurts the 600 series. I have saw a few of AZ Transmission rebuild before on the 600 series and he did use a higher hp torque converter on his rebuilds.If you have any problems just post and I will try to help in anyway I can.If you ever come across a 740 core at cheap price 100 bucks buy it you can buy a rebuilt 740 with a 1 year warranty for less than 2500 bucks from some Allison dealers I know and they may take you 654 for a core.FWIW on your setup where the transmission and engine join there is 2 sets of bolts on the drop down allways check those for tightness they come lose over time    have a great day

[bcaddel]

Problem Solved
We just got the transmission apart and back together this afternoon with a new gasket. Sure enough when we took the rear housing off, the gasket was split in two right around the high pressure passageway.

Put new gaskets in place and drove it 100 miles and it is absolutelly dry and seems to be preforming perfectly.

Thanks to everyone for their assistance

[Busted Knuckle]

Glad to hear that was all it was!   BK 

[Sojourner]

Problem Solved
We just got the transmission apart and back together this afternoon with a new gasket. Sure enough when we took the rear housing off, the gasket was split in two right around the high pressure passageway.

Put new gaskets in place and drove it 100 miles and it is absolutelly dry and seems to be preforming perfectly.

Thanks to everyone for their assistance

Good news...glad you have it fix.

About broken gasket...that would do it. I am surprise they use plain gasket paper to control high pressure passsage. Sorry for thinking copper or O-ring was leaking. Of course broken gasket around passage hole would leaks...if it was unbroken before when installed...I wonder if it would leak later.  Question...did new gasket have build-in soft round seal around the passage holes?

Thank you for the update. 

Sojourn for Christ, Gerald

[bcaddel]

Sojourner
We just installed a plain gasket and there were no built in seals around the passage holes. My son-in-law has been a diesel mechanic for many years but he hasn't worked on transmissions much at all. He talked to one of the mechanics he works with that has done this job many times (apparently the state used to have several mt654 Allison's) and we followed his colleges advise and direction. Your point is well taken and I will remember it if in fact I develop another leak in 12,000 miles. Hopefully the son-in-law will still be willing to assist if that does happen.