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Mav’s M1088A1 Conversion

Mavcaster

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I remember seeing a spreadsheet of common parts and oil weights etc on here but can’t seem to find it anymore. Does anyone have that link? I think I pulled it from someone’s signature.
 

Mullaney

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Mavcaster

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Well I worked on it just about all day to get it running without dying, bled the fuel system several times and drained a bunch of water out of the filter, replaced a u-joint that had been removed, caged and dislodged two frozen brakes and got out of there about 15 min before the yard closed. Drove it non-stop 200 miles back to my house without so much as a hiccup! Now to go through filters and fluids and start making the list. Still need to sort out the check engine light.
 

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Mullaney

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Well I worked on it just about all day to get it running without dying, bled the fuel system several times and drained a bunch of water out of the filter, replaced a u-joint that had been removed, caged and dislodged two frozen brakes and got out of there about 15 min before the yard closed. Drove it non-stop 200 miles back to my house without so much as a hiccup! Now to go through filters and fluids and start making the list. Still need to sort out the check engine light.
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I know you don't want to, but now might be a good time to look at the fuel filter again. Maybe you "caught all the crap" that was sloshing around in the tank. Glad to hear she made it home without a hiccup! Nice looking vehicle...
 

Mavcaster

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Alright well I’ve had a little time to look a lot of things over and found a few of the normal issues but overall, I think I got a pretty solid truck. Truck has no problem building air pressure and CTIS is working as it should (read somewhere a transducer could be changed to adjust pressure setting). I changed the fuel/water separator and fuel filter (which had some pretty nasty fuel in it even after the tank I used getting it home). I plan to fill the tank once more and add a bottle of injector cleaner then change fuel filters again in case some gunk is freed up. Engine sounds like it has a pretty good exhaust leak which is evident from the soot on the side of the block.

Here is a list of things I noticed in case someone reads this in the future or in case anyone has any advice they’d like to pass along to me.

  • CEL is on
  • small leak in roof most likely from turret cover seal
  • broken ground on alternator
  • driver side hydro cylinder bypassed (I assume these are just used for compressing suspension for air travel)
  • cab lock will not engage (engaged when I first got it but now red plunger will not retract)
  • small hydraulic reservoir leak
  • cab bushings falling apart after the voyage home
  • passenger side intermediate brake shoe broken
  • fan disable switch inop
  • exhaust leak at manifold
 

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Ronmar

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Alright well I’ve had a little time to look a lot of things over and found a few of the normal issues but overall, I think I got a pretty solid truck. Truck has no problem building air pressure and CTIS is working as it should (read somewhere a transistor could be changed to adjust pressure setting). I changed the fuel/water separator and fuel filter (which had some pretty nasty fuel in it even after the tank I used getting it home). I plan to fill the tank once more and add a bottle of injector cleaner then change fuel filters again in case some gunk is freed up. Engine sounds like it has a pretty good exhaust leak which is evident from the soot on the side of the block.

Here is a list of things I noticed in case someone reads this in the future or in case anyone has any advice they’d like to pass along to me.

  • CEL is on
  • small leak in roof most likely from turret cover seal
  • broken ground on alternator
  • driver side hydro cylinder bypassed (I assume these are just used for compressing suspension for air travel)
  • cab lock will not engage (engaged when I first got it but now red plunger will not retract)
  • small hydraulic reservoir leak
  • cab bushings falling apart after the voyage home
  • passenger side intermediate brake shoe broken
  • fan disable switch inop
  • exhaust leak at manifold
When you have the ECU scanned to identify that CEL fault, see if they can also copy the engine personality files. The ECUs they used in these 3126s have been known to have their internal keep alive battery fail. When this happens the ECU is bricked and must be replaced. You will want a copy of the engine files to reprogram a replacement ECU for the engine…
 

Third From Texas

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  • small leak in roof most likely from turret cover seal
Can also be the marker lights.
  • driver side hydro cylinder bypassed (I assume these are just used for compressing suspension for air travel)
Delete 'em.
  • cab lock will not engage (engaged when I first got it but now red plunger will not retract)
Rebuild kit available (I paid $20 for mine but the vendor has since gotten out of the business). A few places sell them, though.
  • small hydraulic reservoir leak
Rebuild kits are available. (CallMeColt has a good video with links to kit)
  • cab bushings falling apart after the voyage home
There's a production run being done on a batch. Might check with GeneralDisorder:

Also check your swaybar bushings:
 

Mavcaster

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Well troubleshooting continues…
I went to drive the truck to the gas station a few miles up the road (CEL still on) and it was obviously in a derated limp mode, could barely get out of its own way but would get somewhat up to speed and shifted normally. Pulled up to the pump and it died idling. I filled up and then had a hard time getting her started so lifted the cab a little and pumped the priming bulb which was soft and never firmed up. Thought I might be dead in the water but a couple more cranks and she fired up with the CEL not illuminated. Light stayed off the entire way home and it ran as it should, normal power from what I could tell. Got home and let it sit for a couple hours then had trouble again getting it to run. Starts pretty good but dies frequently, pumped on the bulb again and it began to firm up but wasn’t solid. A few more starts and she was running fine but CEL was back on. I moved the truck to the backyard and it stayed running until I shut it down.

Being that the bulb isn’t getting very firm, especially after driving it to the gas station, I’m leaning towards a very small air leak. I guess I need to put a gauge on the system and see what it gets to until I can get the code read at least.

On a side not and maybe unrelated, I pulled the WTEC codes for S&Gs and I got one…d1 1323 which referring to the manual states ECU voltage high and while monitoring voltage on the gauge during high idle, the needle did jump once to max 32v.
 

Wingnut13

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Could be an air leak, but it takes next to nothing under that little check valve flapper in the pump to make it not work right. Open the drain valve at the bottom of the bowl, if it doesn’t drain but you can hear the file being sucked back down to the fuel tank this is your issue. If it’s working properly you should be able to open the drain valve and use the primer bulb to pump the water/fuel out of the catch bowl.
 

Third From Texas

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For the cab latch leak:

Might try and contact Scott DeWitt. He moved and sold most of his LMTV stuff, but he still lists the cab latch seal kit for sale. But again, get ahold of him to confirm. His old shop used to be here but he moved to NM. I thought he was getting out of the business, but he still lists some things for sale:

 

Mavcaster

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Could be an air leak, but it takes next to nothing under that little check valve flapper in the pump to make it not work right. Open the drain valve at the bottom of the bowl, if it doesn’t drain but you can hear the file being sucked back down to the fuel tank this is your issue. If it’s working properly you should be able to open the drain valve and use the primer bulb to pump the water/fuel out of the catch bowl.
So I know the drain valve was operational at least when I was working on it at the auction yard. That was essentially how I got it to start running consistently as I started to pump and at first frothy fuel was flowing out of the drain hose which then transitioned to normal fuel. Before I did that, it was doing the same things as it is now though, running for a few seconds then stuttering to a stop or just randomly surging then dying after running for a few minutes. I have since replaced both filters but have not tried the drain valve again. I was obviously able to prime the system again after the filter change so that’s why I think if anything related, it’s a very small leak between filter housing and tank.
 

Mavcaster

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For the cab latch leak:

Might try and contact Scott DeWitt. He moved and sold most of his LMTV stuff, but he still lists the cab latch seal kit for sale. But again, get ahold of him to confirm. His old shop used to be here but he moved to NM. I thought he was getting out of the business, but he still lists some things for sale:

Thank you for that lead. I just sent him a message on the site.
 

Lostchain

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Well troubleshooting continues…
I went to drive the truck to the gas station a few miles up the road (CEL still on) and it was obviously in a derated limp mode,
on the subject of checking codes, there are some fair deals on eBay right now for the serial ICE kit. If you get one with the DPA3 in it you can read engine codes with CAT ET and reprogram the CTIS with the Dana software. Should be able to talk to the ABS unit and trans with the right software. I just picked up one of these for my M1078A1.

 

Mavcaster

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Maryland
on the subject of checking codes, there are some fair deals on eBay right now for the serial ICE kit. If you get one with the DPA3 in it you can read engine codes with CAT ET and reprogram the CTIS with the Dana software. Should be able to talk to the ABS unit and trans with the right software. I just picked up one of these for my M1078A1.

Thanks for the tip, I’d like to check with vehicle maintenance on base first though. I’m active duty so hoping they’ll be willing to hook me up with a scan.
 

GeneralDisorder

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Thanks for the tip, I’d like to check with vehicle maintenance on base first though. I’m active duty so hoping they’ll be willing to hook me up with a scan.
Motorpool can hook you up. Buy the Motor Sargent ANYTHING he wants - beer, food, strippers - ANYTHING. That guy can do you solid with TM's, diagrams, troubleshooting, parts from junk that's being turned in for DRMO, etc. You talk to the right people and rub them all the right ways and the heavens can smile upon you.
 

Mavcaster

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Motorpool can hook you up. Buy the Motor Sargent ANYTHING he wants - beer, food, strippers - ANYTHING. That guy can do you solid with TM's, diagrams, troubleshooting, parts from junk that's being turned in for DRMO, etc. You talk to the right people and rub them all the right ways and the heavens can smile upon you.
We’ll see what capabilities they have (I’m Air Force not Army). Flightline vehicle maintenance has some big machines though and I work in a hangar right across the street. May have to strike a deal or two but I’m pretty good at sweet talkin’.
 

GeneralDisorder

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We’ll see what capabilities they have (I’m Air Force not Army). Flightline vehicle maintenance has some big machines though and I work in a hangar right across the street. May have to strike a deal or two but I’m pretty good at sweet talkin’.
Doh! Chair Force doesn't have these trucks. But they should have a J1939 interface to talk to some systems.

Make friends on the local Army base side of things. Trust me - you want to find a fellow veteran on the Army side. A Motor Sargent for a good sized unit with a lot of trucks can be your new best friend. And they know these trucks well.
 
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