M917 tranny questions.... update

[scooter01922]

Hey guys, its been a LOOONG time since i have been around.....again. Anyway, my bad influence of a boss clued me into a local auction with some trucks. Had a few 5 tons, a 915 and a trio of 917's. Simply could not pass up a 917 for what these were going for so.....yeah i bought one. Ran down today and with a couple batteries it started damn near first revolution. Has been at a state police driving instruction site for new cadets for the past who knows how many years. Was used to plow the formerly military runway that is now the practice track. Odometer reads a bit over 10k since overhaul in 04 in TX. Was listed as "bad trans, no gears" but for the price i paid i couldn't care. Today while running it aired up great and surprisingly enough went right into both 1st and reverse. Its got the 16 speed, BTW, no idea the other gears but both first and reverse grabbed well enough to move the truck at idle even with the brakes locked on. Thats my first 917 question. Shouldn't it just sit there in 1st or reverse? I thought they were like a true auto in that respect.

 

[simp5782]

Hey guys, its been a LOOONG time since i have been around.....again. Anyway, my bad influence of a boss clued me into a local auction with some trucks. Had a few 5 tons, a 915 and a trio of 917's. Simply could not pass up a 917 for what these were going for so.....yeah i bought one. Ran down today and with a couple batteries it started damn near first revolution. Has been at a state police driving instruction site for new cadets for the past who knows how many years. Was used to plow the formerly military runway that is now the practice track. Odometer reads a bit over 10k since overhaul in 04 in TX. Was listed as "bad trans, no gears" but for the price i paid i couldn't care. Today while running it aired up great and surprisingly enough went right into both 1st and reverse. Its got the 16 speed, BTW, no idea the other gears but both first and reverse grabbed well enough to move the truck at idle even with the brakes locked on. Thats my first 917 question. Shouldn't it just sit there in 1st or reverse? I thought they were like a true auto in that respect.View attachment 872399

It won't pull till you get to 1100rpms. It takes oil pressure to engage the front clutch

If you don't want to buy a 2500$ ring and pinion I wouldn't advise moving it with the brakes on again. They are very loose tolerance gears and snap teeth very easy. They even do it heavily loaded in a low gear with the Jakes on high

 

[scooter01922]

Interesting, was definitely idling less than 1100, more like 500 and yet was pulling like a mofo. I didn't really intend for it to go anywhere with the brakes still on. Just wanted to see if it would drop the rpm a touch to signal it was doing something since it was listed as bad trans. Sounds like something needs a little attention. BTW, read your whole 915 thread this past weekend as mandatory reading before i went to check the old gal out, damn nice work.

 

[FullSpecial]

Are your brakes caged or way out of adjustment?

 

[scooter01922]

Entirely possible, very probable they are way out of adjustment. Didn't look at them much except to see that they released. Before it actually moves very much i'll certainly adjust them. They did do something though as it was dragging the engine down pretty good, just not enough to stall it.

 

[NDT]

Something is very much outta whack in the transmission. At idle, the truck should not move.

 

[scooter01922]

Good to hear that all my reading was not in vain, i did retain something. I guess a deep dive into the TM's will be in order once its gets somewhere safe. Going to be towing it home anyway so it only has to move to get on the trailer. Worst case scenario a short slow drive to somewhere else on the property. Circling back to my bad influence boss, " we should buy some trucks, i can send the landoll to fetch them". Sure is nice to know it should be an easy recovery comparatively but its that much harder to NOT buy something when transport isn't that much of a worry. Now all i need to figure out is how low we can get the trailer deck, gonna be a wee bit close on legal in that dimension.

 

[scooter01922]

OK, well its safely at the yard where i work. Was too damn tall for the landoll and had to call in a local lowbed outfit we use a lot. Was still 13 foot 2 inches on the lowbed so keep this in mind if you are thinking of dragging one of these home. On the day of loadout i started it up, let it build full pressure and moved it out into the open so we could put the plow in the bed. Got the plow in there and by that time transport had arrived. Wouldn't you know it....the truck refused to move at all. Pushed/ pulled / coerced it on there with a loader. Back at the shop i figured first order of business in terms of ease and cost would be to drain the pretty dark smelly fluid out of the tranny. Need to order up a TM but i was figuring this would be too straightforward to screw up. That is until i went looking for the suction screen mentioned in the door maintenance tag for cleaning. Where in the heck is that danged thing? I have a drain plug, a drain plug with a 3/4 square in it and nothing else besides a second PTO plate. The fluid in there was NOT helping things and i wouldn't want it running for diagnostics with that crud circulating. Seemed too thin, was dark and had a seriously bizarre smell, not burnt smelling, just smelly, there was at least the correct amount in there roughly.

 

[simp5782]

OK, well its safely at the yard where i work. Was too damn tall for the landoll and had to call in a local lowbed outfit we use a lot. Was still 13 foot 2 inches on the lowbed so keep this in mind if you are thinking of dragging one of these home. On the day of loadout i started it up, let it build full pressure and moved it out into the open so we could put the plow in the bed. Got the plow in there and by that time transport had arrived. Wouldn't you know it....the truck refused to move at all. Pushed/ pulled / coerced it on there with a loader. Back at the shop i figured first order of business in terms of ease and cost would be to drain the pretty dark smelly fluid out of the tranny. Need to order up a TM but i was figuring this would be too straightforward to screw up. That is until i went looking for the suction screen mentioned in the door maintenance tag for cleaning. Where in the heck is that danged thing? I have a drain plug, a drain plug with a 3/4 square in it and nothing else besides a second PTO plate. The fluid in there was NOT helping things and i wouldn't want it running for diagnostics with that crud circulating. Seemed too thin, was dark and had a seriously bizarre smell, not burnt smelling, just smelly, there was at least the correct amount in there roughly.

It's 15W40 engine oil or in cold climates 10w oil. So yes it will be thin.

You have to pull the passengers side PTO cover to access the screen.

@ponway has even found rags from the building of the transmission in the pickup screen.

 

[scooter01922]

It's 15W40 engine oil or in cold climates 10w oil. So yes it will be thin.

You have to pull the passengers side PTO cover to access the screen.

@ponway has even found rags from the building of the transmission in the pickup screen.

Yeah, i read up on the oil. Thankfully 5 gallon buckets of rotella 15w40 are still somewhat reasonable on cost and i happen to keep a couple on hand anyway. Even for that it looked thin, not exactly a lab analysis but whatever. I did pull that plate, but just saw gears, guess you gotta reach down in there to find the screen. Gears looked superb for whats its worth.

 

[simp5782]

Yeah, i read up on the oil. Thankfully 5 gallon buckets of rotella 15w40 are still somewhat reasonable on cost and i happen to keep a couple on hand anyway. Even for that it looked thin, not exactly a lab analysis but whatever. I did pull that plate, but just saw gears, guess you gotta reach down in there to find the screen. Gears looked superb for whats its worth.

It's on the driver's side right next to the base of the transmission

Just not easy to pull the pto.

There is an oil pressure test port on the side of the transmission up in the housing groove

The cat 7155 manual is in the TMs here

 

[scooter01922]

It's on the driver's side right next to the base of the transmission

Just not easy to pull the pto.

There is an oil pressure test port on the side of the transmission up in the housing groove

The cat 7155 manual is in the TMs here

Good to know that TM is on here, gonna need several frosty adult beverages and a couple hours of free time to dive into that one. Sure hope i don't have to pull the PTO itself, would be some pretty poor maintenance planning to require PTO removal to clean the screen. Not that getting the PTO block off plate on the pass side was FUN but it wasn't bad. With some new oil in there i'll be finding that test port for sure. Its very nice they designed in so very many test ports on these trannys. They may have issues but at least you have been given a way to get real data unlike a LOT of things these days.

 

[scooter01922]

Yeah, so poor maintenance planning it is. Could not find the cat tranny service tm in the tm section. Reaching in the pass side pto hole I can feel the suction tube.... And also the 4 bolts that secure it. Only way to get to the ones on the driver's side appears to be pulling the PTO. Talk about a great way to ensure that screen NEVER gets cleaned.

 

[simp5782]

Yeah, so poor maintenance planning it is. Could not find the cat tranny service tm in the tm section. Reaching in the pass side pto hole I can feel the suction tube.... And also the 4 bolts that secure it. Only way to get to the ones on the driver's side appears to be pulling the PTO. Talk about a great way to ensure that screen NEVER gets cleaned.

M915 Series Trucks, CAT 7155 Service Manual

CAT 7155 Service Manual is scanned and also went through OCR so it can be searched. Scan by me (Mullaney) Book provided by 290smallcam

www.steelsoldiers.com

 

[simp5782]

The screen is magnetic so it will catch that and any large silicone bits that get into it.

 

[scooter01922]

M915 Series Trucks, CAT 7155 Service Manual

CAT 7155 Service Manual is scanned and also went through OCR so it can be searched. Scan by me (Mullaney) Book provided by 290smallcam

www.steelsoldiers.com

There we go, I knew it had to be on here somewhere. Thank God for SS, keeper of all MV knowledge

 

[scooter01922]

Interesting, that whole manual and it says nothing at all about cleaning that screen. Does say at one point in the reassembly part about installing the ONE bolt that secures the pick up tube. Looks like the 4 of them together hold the oil pump together. Good thing I decided to do some reading on lunch.

 

[scooter01922]

Anyone that has pulled that screen care to tell me what bolt is the one that retains the suction tube? Pulled the top one out, i don't think its that one unless its really stuck in there. Even with the previous link i'm not seeing the retention method clearly. Can't feel any type of retainer that any bolt passes through. Per that manual those 4 bolts are keeping the oil pump together, rather not have that fall apart in a spot you can't even see.

 

[ponway]

It's 15W40 engine oil or in cold climates 10w oil. So yes it will be thin.

You have to pull the passengers side PTO cover to access the screen.

@ponway has even found rags from the building of the transmission in the pickup screen.

HaHa! Yeah, it was actually a reinforced paper shop towel that had been stuffed in the drain of the main gear case for the rear clutch! Pulled the rear clutch off and it was sandwiched between the two. A rebuild from Fort Polk. Had other instances of shoddy workmanship in 2 other Fort Polk overhauled 7155 transmissions.

 

[simp5782]

HaHa! Yeah, it was actually a reinforced paper shop towel that had been stuffed in the drain of the main gear case for the rear clutch! Pulled the rear clutch off and it was sandwiched between the two. A rebuild from Fort Polk. Had other instances of shoddy workmanship in 2 other Fort Polk overhauled 7155 transmissions.

Fred should be sent to the gas chamber