We purchased a mc7 in Texas last september from my parents. It had not been driven for almost 4 years when be brought it to Reno, Nv. We have put over 3,000 miles on it in the last 3 months with no problems. We headed to Elko Wednesday night for Turkey Day and after about 100 miles the transmission started shifting hard and the bus actually started slowing down. I stopped to check things out and noticed a layer of fluid on the toad. When I checked the transmission fluid it didnt register so I went and got some and put it in (Dextron III). After about 50 miles the same thing, I checked it and it didn't register on the stick again. I drove the next 200 miles stopping every 40 miles and adding a gallon of fluid. The transmission is a Allisno MT 654.
It appears to be leaking from the gaskets at the end of the transmission just before the output housing. I was aware that with it sitting for several years and I might have some gaskets or seals leaking but a gallon every 45 minutes is that possible from a gasket leak. When I look underneath with the engine idling it drips from these two gaskets but not at that rate, I guess it could be under pressure at highway speed and squirt out. I am hoping its something I could possibly fix but I dont think I would attempt to take the transmission apart to replace the gaskets.
There is a Smith Detroit-Allison shop here in Elko but I dont see any low price guarentee in their ad in the phone book so I am guessing it will be big bucks to have them turn a wrence.
Any thoughts or ideas? Maybe a magic stop leak? Would appreciate any suggestions or advice
bcaddel, wash the trany good, more than likely it has blown a o-ring where the cooler fitting attach to the transmission or a hose
have a great day
Thanks for the suggestion, you suggestions sounded really promising but both the hoses are nice and dry. One on the side and one on the top. I did find some antifreeze on the top of the transmission from a hose passing over it, so I guess that will be another project for a later day.
Is there any change some transmission stop leak would do anything? I can see a light flow of transmission fluid coming from where the gasket sticks out. I tried tightening the bolts but they are all pretty tight. It just seems like too much fluid for a gasket that is in place and not missing any material..
bcaddel ; check the fitting where the hoses fitting connect to the transmission they have a o-ring with a lock nut, I don't think it is leaking from the gasket or you would have a puddle every time you stop, it is your trany but me I would not use a sealer in the Allison,are you having any problems with 1st gear I ask because the 1st gear clutch pack is behind that cover and when they go it will put more pressure in that part of the transmission have a great day
I wouldn't use a sealer either, sound like your leak is quite bad and the chances of a additive working would be slim to none with my experience anyway. You'll end up having to fix it in the end anyway.
Good Luck
Have fun!
Check to see if your transmission has a vent breather on top of it.
It might look like the same kind you would find on a drive axle.
Make sure it's clean and not clogged - IF your trans has one.
Bcaddel, a word of advice for you let Smith check and tell you the trouble but if they want to pull the transmission and repair it you will be looking at around 10 grand from them.If you need a rebuild buy one from www.utexchange.com for around 3 grand been there done that with Smith and you can change it yourself in 1 day with a transmission jack. Good luck
bcadell, they do have a vent up by the torque converter housing it will have test ports at the rear check for any missing plugs and check the governor plate at the rear for leaking and spray. have a great day( if you can)
It looks like the breather tube is actually gone. We are going to head into town and try to get one. It may be plugged up and that could be what caused the leak from the gasket. I dont hold out much hope for a fix but it may slow it down on the trip home The Smith detroit allison shop said they would have to order parts and it would be a week, so we will try and do what we can and limp home. Hopefully we can purchase 4 or 5 gallons of fluid in gallon containers so it isnt such a pain stopping every 45 minutes. Really hopefully the breather tube releives the pressure and the leak decreases drastically.
Thanks So Much For all the suggestions, I will check back in a couple of hours when we get back from hunting for a breather tube.
All threaded openings on the trans are standard so it should not be hard to make a tube and route it high and down.>>>Dan
main culprit main seals first front then rear
Thanks for all the suggestions, I had some hope the breather tube missing might have caused the vent to be blocked building up pressure and causing the gasket to leak. No such luck though. We got the breather tube replaced and drove back to Reno this afternoon (300 miles) and it took 5 gallons of transmission fluid to make the trip.
This leak happened so suddenly, it just seems like something is causing preassure to build up and forcing the fluid past the gasket. I think I will try to search the internet for any clues before I take it to the Allison shop as I know that will cost a bundle. We have only had the bus a few months and just love taking trips in it as it really does great on the road. We just got the jake brakes put on a couple weeks ago and installed a tach this week-end so once we get this issue resolved with the transmission leak we will hopefully be able to take off for a short trip and test it out. Thats assuming diesel keeps going down, I probably won't be able to afford to go very far at all after the transmission dudes get done with me.
Does anyone think there is much of a possibility its just a dried out gasket (it set for 4 years until last Sept) and replacing the gasket will resolve the issue or is the general thought there is pressure building up forcing the fluid out and another gasket would just start leaking after a few miles? There is no oil leaking from the front or rear seal or the cooling hoses just the bottom of the rear gasket....
bcad,
By all means change out that gasket. You are getting close to taking her in and then "taking it". I heard advice to get a rebuilt for 3 grand and doing it yourself in a day or two with a rented trans jack. That would be my "Worst Case" and I would do a lot of work replacing minor stuff, hunting and pecking and disassembling things before I took the plunge. I still think that Alison/Detroit shop would be your best bet for a diagnosis only effort. If they say it must be rebuilt then change it out yourself after you limp home and get access to some help. Possibly a fellow Knut or two. :)
God knows I have only seen pics of an Alison Tx so take this for what it might be worth. Doesn't the 4 speed auto take the same 40 wt oil as the engine? I know I have seen that said about some trans and it stuck in my mind....or what passes for what is left of it. :P
Good luck Buddy and I agree that this is a strange problem. I thought one of the most telling observations was that the thing works normally in all regards except leaking. Doesn't sound to me like a candidate for a replacement unless the case is cracked. :o
john
I may not be an expert but I can tell you this: DO NOT USE THAT TRANNY STOPLEAK. That WILL result in a worst case. Don't ever put anything in there but the recommended fluid. Don't ask me how I know this or why this is such a SORE SUBJECT....spoken through clenched teeth. ;D
bcaddel;can you tell us when the last time the transmission was serviced that is unusual that gasket leaking and not the output shaft seal.If the bus set for 4 years the rear clutch pack could be deteriorating the dexron III is not good for the older clutch pack materail
JohnEd; you can use C4 15/40 in the transmission but I never heard of or knew anybody using straight 40W
I dont know when (or if) the transmission was last serviced. My Dad kept pretty good records and I have most of them. I dont see see anything about a transmission service. I do know he purchased the MT654 Allison transmission from Arizona Transmission and Engine Exchange on 8/28/1998 for $9,754. About a year later he then had a Hub Odometer installed when he had the 8v-71 rebuilt by Stewart & Stevenson Power on 5/21/1999 for $9,169.38. I only mention the pricing because it indicated to me they appear to be quality products.
The hub meter now reads 11,771 so my assumption is the transmission has about 12,000 miles on it (3,000 since Sept when we purchased). My dad has lost much of his memory for these type of details (haven't we all) and since there isnt any receipt in the paperwork I assume it has not been serviced since it was rebuilt. I read somewhere they need to be serviced at 5,000 after rebuild so having 8,000 when I purchased it makes me think he may have overlooked having it serviced. Do you think that could be the culprit?
The transmission preforms execellant until it gets about 6 quarts low (that happened on the trip to elko last Wednesday night) and we noticed a loss of power. We pulled over and thats when we discovered the loss of fluid. Everytime we fill it up it works great and then in about 50 to 70 miles I check it again and it will be 4 to 5 quarts low and I fill it up again. Makes for a real messy toad...
I am pretty sure it had Dextron III in it from the rebuild since it was/is bright red in color. I did read on one of the Allison web site that Allison recommends Dextron III,TranSynd (synthetic fluid I think), SAE 10W. SAE 15W-40, SAE 30, SAE 40 so I stuck with the Dextron III. I dont know what the Tranynd fluid looks or smells like so it could have had that in it. Do you think not having the filter changed could have cause these problems?
Baddel, the transmission oil should have been changed before driving after setting that long the ATF with all the additives will become acidified after a long period of time that is why a rebuilt transmission will never have oil. I know Kim at Az Transmission some don't like him but he does turn out a good product give him a call before you take it to dealer and he may can answer your question.
good luck
I never even thought of changing the fluid in the transmission, we did change the fuel filters and engine oil. Live and learn I guess. I am assuming after going through 10 gallons of fluid over the last few days that could that as a transmission fluid change??? I am reading that I need to get the filter changed also. I don't see a externial filter so I assume it is internal.
bcaddel; install you a remote filter they don't cost that much and not hard to install you will save time and money you can buy the base and filter at NAPA.I wish the best for you but do not try and replace the gasket yourself that is not a diy project you have the clutch pack to worry about falling out. have a great evening
Bcad,
2stroke has me hands down on first hand info. I guess the gasket is a bridge too far for us.
No, you have not changed the fluid. It is a class problem in chemistry to find out how many times you have to replace 1 gallon in a ten gallon tank to get to 50% changed. It is way more than you might think using common sense. If all is well an automobile trans gets the pan oil changed but not the torque converter so it gets maybe a 20 percent change. That "change" is expected to "rejuvenate" the rest of the fluid. Some torque converters have a plug in them and you can drain the torque converter there. I would expect the Allison to have a Torq drain plug but I don't know. I do know that if you are advised to change the fluid a couple gallons in and out won't do that. If you changed your as often as you indicate and with as much volume as you did you might be there. Have the fluid analyzed. You should do that on an annual basis anyway but with your problems I don't know if you should analyze it now or wait for the flush or?
Sorry about your misfortunes.... Just an idea. Why don't you try having a friend or your wife put the transmission in gear with either the parking brakes or the pedal brake engaged? Because the system will be pressurized maybe it might give you a clearer view of where it is leaking. Chock the wheels so you don't end up running over yourself of course.
Let us know what you find out
And, I'll add, stop driving it until this gets better identified.
Or you'll be buying a new one!
happy coaching!
buswarrior
If you do crawl under I would be sure not only to chock the wheels, but also block up the bus just in case an air bag or valve or something causes the suspension to drop.
I don't believe it's your trans, not sure what it is but my guess is something simple. As mentioned by others , I'd try lots of other things before changing the trans. Could be as simple as the gasket.
Good Luck
MMa2S,
In another post here it was mentioned that the 4speed manual takes 40wt oil, same as the engine. Not the 4 speed Alison Auto. I guess I got my 4 speeds confused. Sorry! Almost the same though, right? Nitpicker! ;) ;D ;D ??? ::)
Thanks,
John
Allison approved 40 wt motor oil for HT740s. Same as engine oil. I don't use it, but it worked without issues.
Same for MCI power steering systems. If it's brown, its motor oil. If red, its Dexron.
FWIW, I wouldn't go to the trouble of changing the transmission oil and filters if you have identified a housing gasket leaking. That's a waste of time and money.
If you have not precisely visualized the leak, noting exactly where it's coming from would be the next step.
Identifying the leak's exact location will allow you to call Allison dealers and get a quote without wasting time on diagnostics at the dealer.
You may wish to locate a service manual for your trans. You might find that it's more 'doable' than you think...may not too. A safe place to work beneath the bus will make the job much more doable.
Good luck, JR
JR, never said 40w wasn't approved but I have never seen it used here in the US maybe where it's a 140 in the shade but every manual I own states 30W no mention of 40W and the 30W has to be preheated at 32 degrees , and this guy does not want to pull the end plate off if he doesn't know what is involved. have a great evening
Quote from: makemineatwostroke on December 02, 2008, 07:50:21 PM
JR, never said 40w wasn't approved but I have never seen it used here in the US maybe where it's a 140 in the shade but every manual I own states 30W no mention of 40W and the 30W has to be preheated at 32 degrees , and this guy does not want to pull the end plate off if he doesn't know what is involved. have a great evening
Nope. You didn't.
I was actually responding to John's post...should'a made it clearer. John was correct about the 40wt motor oil.
I wasn't recommending 40 wt either. Just offering up a useless factoid that it was an option under cetain circumstances.
I tend to agree with you on DIY auto transmission projects, but, with a place to work, some assistance from any auto trans guy, and a manual that describes what special tools will be required..who knows. Most DIY folk wouldn't get past the DS yoke/flange retaining nut. Some will.
Unless one is pretty wealthy, dealing with an authorized Allison dealer could be a show stopper.
Bcad will definitely want an estimate before allowing anyone to dink with his transmission. He may well find that buying a good takeout and installing it is cheaper than allowing an authorized dealer to replace a gasket....I don't know. But I would want to know the options (pitfalls?) and potential cost of repairs prior to the bus being rendered undrivable.
I think like a poor man...obviously not everyone approaches repairs as I do. But losing control of the situation is what I wish to avoid. The Allison tech sees a $24,000 commercial transmission in which all systems must be returned to proper working order irrespective of cost. :o
Cheers, JR
Thanks for all the input and suggestions. I took Luvrbus's advice and called the place where our transmission was purchased AZ Transmissions & Engine Exchange. I talked to Kim there and he said ship the transmission back to him (if I can get it out from under the bus) or drive it back and he felt he would be able to fix it for under $1,000. After we talked and I described the severity of the leaks (a gallon an hour) he said it could very well be the gasket on the rear of the transmission.
I am thinking about purchasing a couple of 5 gallon containers of Dextron III and heading to Tucson (850 mi from Reno). I am still a working dude so it may take some doing to get off work for the wife and I but that may be what we do. I have also thought about going down to the Allison shop and talking with them about changing the gasket but no matter what they say I am quite confident once the transmission is apart there will be many additional charges that will be much more than the $1,000 it will cost in fuel and ATF fluid to drive to Tucson
Plus I have a new Jake Brake, Tow Bar and Tach that I am really anxious to get some miles on them all. I will keep you posted as to how we fix the problem and the trip if we make it.
I would not count on the leak rate staying the same. It could suddenly get much worse leaving you stranded or with a totaled tranny and a big tow bill.
If the leak is just seepage from a non pressurized gasket, a careful cleaning of the exterior of the case and some good sealer might reduce or stop the loss of fluid until proper repair.
I would be present when whoever pulls the leaking gasket to see if it was installed properly. If not, the tranny shop that did the repair should stand behind it.
Good luck
Don 4107
I just returned from Smith Detroit Allison here in Reno. The service desk told me I should try putting a COPPER WASHER on the bolt that goes through the gasket. He felt there was a good chance this would stop leak. If that didn't work he said it would cost about $1,100 to replace both the front and rear gasket.
I am definatelly going to try the copper washer trick, and most likely will let them do the repair instead of taking the drive to Tucson with the leaking transmission. Does anyone think the copper washer has a chance of working?
willing 2 bet you could do it for less than $300 including parts & tools;-) but while you have it out y not rebuild? check out price of master rebuild kit. transmission jack $175 font rear seal probably$20 a piece
I will take that bet circusboy the snap ring puller alone is over $400.00 for a Allision.This guy is headed in the right direction by listening to the Allison dealer, but I don't know about the copper washers it may work for him if it leaking out the bolts
have a great day
Quote from: Clownboy
willing 2 bet you could do it for less than $300 including parts & tools;-) but while you have it out y not rebuild? check out price of master rebuild kit. transmission jack $175 font rear seal probably$20 a piece
Clownboy you have obviously not done much work on buses! First off a $175 tranny jack will fold over and get you killed or hurt for clowning around with such small tools for heavy equipment repairs (pun intended!) And if you ever find a front or rear tranny seal for an Allison transmission feel free to buy all available and make yerself a profit of around 100% or more while still helping someone save $! I dropped the subject rather than responding on your thread about where& what to look for? (that has been asked and repeatedly answered over and over in the past to have a qualified bus mechanic inspect it with you!
Where you more or less slapped Dallas, Mike, Sammy, Luke, Cole, Tom, Jack, JR, BW, Bruce, Charles, Clifford, Sonny, Arthur, myself and many others (I can't mention them all as I have memory lapses and there are too many! here who do or have made our living working on buses and willingly, and lovingly give our time and advice free here on the board
in the FACE! While at the same time asking for our advice! So even though I may get an trouble I urge to learn the difference of working a VW bus and a
REAL BUS, before giving advice that can hurt, kill or cost someone mega dollars and much grief because you haven't got a clue as to what your talking about! These are very big units and not your VW or Chevy camaro! An Allison transmission in one of these buses weighs as much as a VW and half as much as a camaro! So if you'll stick to
CLOWNING around those of us who are experienced will stick to giving
SERIOUS ADVICE! (again pun intended!)
;D BK ;D aka class clown of the MAK board! LOL!
OUCH!
BK, how do you really feel?
Jim
Quote from: Busted Knuckle on December 03, 2008, 11:39:50 AM
Quote from: circusboy90210 on December 03, 2008, 11:16:56 AM
willing 2 bet you could do it for less than $300 including parts & tools;-) but while you have it out y not rebuild? check out price of master rebuild kit. transmission jack $175 font rear seal probably$20 a piece
Clownboy you have obviously not done much work on buses! First off a $175 tranny jack will fold over and get you killed or hurt for clowning around with such small tools for heavy equipment repairs (pun intended!) And if you ever find a front or rear tranny seal for an Allison transmission feel free to buy all available and make yerself a profit of around 100% or more while still helping someone save $!
I dropped the subject rather than responding on your thread about where& what to look for? (that has been asked and repeatedly answered over and over in the past to have a qualified bus mechanic inspect it with you! Where you more or less slapped Dallas, Mike, Sammy, Luke, Cole, Tom, Jack, JR, BW, Bruce, Charles, Clifford, Sonny, Arthur, myself and many others (I can't mention them all as I have memory lapses and there are too many! here who do or have made our living working on buses and willingly, and lovingly give our time and advice free here on the board in the FACE! While at the same time asking for our advice! So even though I may get an trouble I urge to learn the difference of working a VW bus and a REAL BUS, before giving advice that can hurt, kill or cost someone mega dollars and much grief because you haven't got a clue as to what your talking about! These are very big units and not your VW or Chevy camaro! An Allison transmission in one of these buses weighs as much as a VW and half as much as a camaro! So if you'll stick to CLOWNING around those of us who are experienced will stick to giving SERIOUS ADVICE! (again pun intended!)
;D BK ;D aka class clown of the MAK board! LOL!
concepts all the same just different scale of co$t & weights . a unit weighing more does not affect t key concepts. the class clown ends up being the smarter one in the long run though.
however it's not a slap 2 say if I knew typical issues with busses I would not need bus mechanic as that's y I'm here 2become my own expert,thanx
btw a$175tranny jack can lift 4tons so you r not totally correct. howeve we will see, & this is not a competition bta learning experience. In my fields of endeavor even the most seasoned hand can learn from a total greenhorm, & circus life is a micrcosim of society so I got to learn bout most anything there is2 know about because Igot2 go see things that interest me &ask questions directly of top expertsif they werenot allready doing something for ourshow, or just happened 2 b there.(met many famous,rich ,celebrity orotherwise .
Well the copper washers didn't work. I cleaned the area up pretty good and now you can see it is just the one gasket leaking, the gasket on the thread side of the bolt so the washers didn't have a chance. Do you think if I have the Allison Transmission people replace this gasket it will solve the problem. There is no fluid leaking anywhere else just the gasket where these two metal surfaces meet. I attached a picture of transmission leak to this email, you may have to click on it to open it.
I was a little concerned that something is causing excess pressure inside the transmission forcing the fluid out but this fluid came out immediatelly after starting the engine, and the dip stick is never forced out of its holder from pressure so maybe it is just the 4 years of sitting idle caused the gasket to dry out. There does not appear to be any cracks in the metal surfaces anywhere near the leak.
The transmission runs perfect when isn't low of fluid. Before I spend the $1,100 to have them replace the gasket I would like to have a warm fuzzy feeling that there is a good chance it may solve the problem.
bcaddel; can you see the gasket i can not tell from the photo.some rebuiders used RTV (black) silicone to assemble the transmission which Allision approved but it never worked for us.Me i would drive the bus to Smiths and if the diagnostics confirm it is the gasket, do it most Allision dealers don't get heavy in your pocket till it is a total rebuild of your transmission instead of a exchange. have a great evening
looked up prices4 this gasket on several allison products $5 even if you only break even fixing it bybuying tools &manual you will neverbb stuck like that again.
Quote from: clownboy
concepts all the same just different scale of co$t & weights . a unit weighing more does not affect t key concepts. the class clown ends up being the smarter one in the long run though.
however it's not a slap 2 say if I knew typical issues with busses I would not need bus mechanic as that's y I'm here 2become my own expert,thanxbtw a$175tranny jack can lift 4tons so you r not totally correct. howeve we will see, & this is not a competition bta learning experience. In my fields of endeavor even the most seasoned hand can learn from a total greenhorm, & circus life is a micrcosim of society so I got to learn bout most anything there is2 know about because Igot2 go see things that interest me &ask questions directly of top expertsif they werenot allready doing something for ourshow, or just happened 2 b there.(met many famous,rich ,celebrity orotherwise .
Clownboy the remark I was remarking about was where you don't trust us mechanics ESPECIALLY DIESEL MECHANICS! (most of us bus MECHANICS qualify here !)And trust me the el'cheapo harbor freight trans jack will fold over side ways under the weight of an Allison! I know this for a fact when one of my mechanics and my silly uncle pulled a HT740 out of a MCI 9 with out pulling the engine together while I was off on a trip! They folded that jack over and almost hurt both of themselves, destroyed the trans pan, and still couldn't get it out from under the bus! BTDT! Sometime you'll learn more by listening to those who know, rather than pretend to know it all while giving bad/false advice!
Also like my Granddaddy (god rest his soul) used to say
"ya know sometimes it best to keep yo mouth shut, and let folks think ya a fool. Than to open it and remove all doubt!"FWIW ;D BK ;D
I don't ever think I have seen BK angry before :o
Bcaddel....I believe you have a missing copper or been reused (a no-no) or damage "O" ring gasket in-between low clutch housing and main transmission housing in the oil pressure passage...there 2 of them next to each other in parallel. See photo with description labeled. It could be unclean surface around the housing's mating surface such as part of old gasket over new one to cause not enough compression to seal to seal well from "O" ring gaskets. It looks like it been tamper with lately and poorly reassembled.
The light green is the passages in the photo. You notice there two pressure taps.
This involves removing tail shaft housing and low clutch housing. Allison mechanic job to repair and reassembled with proper end play.
FWIW
Sojourn for Christ, Gerald
To all bus nuts...here a good example why photo is a good thing and save all the rehashing of all sorts of guessing statement. It allmost like being there.
Thank you bcaddel for sharing that photo and a great one too.
FWIW
Sojourn for Christ, Gerald
My 2 cents worth !
Years ago I replaced my 4 speed trans with a used 10 speed. It was very grungy on the outside with oil and road grime. I pressure washed it, and then one by one I removed every bolt that entered into and THRU the casing and put shellac gasket goo on the bolt threads and put them back.And painted both trans and engine gray...........
I also did the same to the 8V71 where bolts went into water or oil galleries
There is NO oil or water stains on engine or trans!!!!............I am thinking this MIGHT stop the leaks on your gasket bolts..........HOPE SO .Ken.......... 05 Eagle
Gerald
Thanks very much for your input, your comments seem to be right on track but I am 100% certain the transmission has NOT been tampered with in any way. It was installed in the bus by AZ transmission and engine exchange in Tucson in 1998. It has ran for 12,000 with no issues or leaks. It just suddenly started pouring oil out while driving down the road (1 gal pr hour). I took two bolts out yesterday and put the copper washers on them as recommended by Allison mechanic and cleaned it up to see what would happen. That is when I discovered it was coming out the gasket on the threaded end of the bolt only. Does that change your thoughts any?
My son-in-law is a diesel mechanic (but not a transmission mechanic) and worked for Smith Detroit Allison for 6 years, he has been a diesel mechanic for the State for the last 10 years. (I have come to appreciate the value of a quality son-in-law over the last 3 months) He has looked at the transmission manuel for the MT 654 and feels he can make the repair properly if it is only the gaskets we need to replace. Do you think that would solve the problem or just open a can of worms and it would have to be reassembled by a allison technician.
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
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
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! ;D BK ;D
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.
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
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. 8)
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
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.
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
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
Glad to hear that was all it was! ;D BK ;D
Quote from: bcaddel on December 12, 2008, 08:51:00 PM
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
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.