Working On The M923A2

mkcoen

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Well I tend to start my refurbishment threads all the same so here goes for the M923A2.

GL listed the truck as a 2001 and it wasn't until after I had already purchased and insured it that I found out they only built them from 1988-1993. While it looks good it turns out they mis-labled it by 10 years. The truck has an actual delivery date of 1991 so at least fits in with the correct production years. It doesn't bother me that GL screwed up as I'm used to that but it kind of bothers me that I didn't' do a little better research. I knew I hadn't seen one that new but just chalked that up to the military holding on to the newest ones.

Luckily this recovery was only about 50 miles from home. My biggest fear was that it was going to have big enough issues wrong that I'd need to have it towed home and really didn't want to sink that much more money in to it. I sold my MKT-99 in order to buy it and came out about $300 shy of covering the full cost plus fees of the new truck. I tried to call to set an appointment to inspect it before the sale but the GL rep would never call me back and I ran out of time and just went off the photos (ergo the wrong year expectation).

Appointment was set at 1300 today and when I showed up to meet the GL rep (it's an off site location for GL) he had a Army Reserve PFC with him. We went through the gate into the motor pool, located the truck, and the PFC pulled (I believe) an MK48 up to slave it off. It started on the first crank, built air immediately, and the PFC drove it out the gate into the parking lot. As this was a working location for the Reserve we wanted to move off site and stop to check everything out so drove down the access road to a Target parking lot and pulled in to look things over. Here's what we found both there and once home:

1) Batteries are DEAD! Alt meter stayed just above red all the way home (about 50 miles) and when I got in the drive and shut it down the meters wouldn't even come on when I tried to start it back up. One of the 4 had 1.6v so I'm thinking that one won't recover. I doubt the others will either but they may have a shot.

2) There's a class III fuel leak in a doohickey (I believe it's the fuel transfer pump, actually just the top part with the wires is leaking) that I have to find out the part name for. I think it should be an easily acquired part and in a wide open place to change so other than having to do it not really a big deal.

3) It has A/C! That would be where the cab cover seams have separated letting a nice breeze in above the windshield.

4) Something is hinky with the CTIS (surprise, surprise). Not airing up and all the lights are blinking on the controller. I think someone said to disconnect the controller to reset it and then see. Not going to happen until I have 4 working batteries.

5) Left headlight is out.

6) No tools of any kind including the winch for the spare tire. They stripped it pretty good before turning it in or while it was sitting in the motor pool.

7) Needs new wiper blades.

All in all looks like some pretty easy fixes. The transfer pump (if that is what it is) will probably cost a little bit but is easy to get to. The batteries, while expensive, is another easy fix as are the wiper blades and headlight. I'll probably have those things done by the end of the weekend. The roof is probably going to be the hardest to handle. I'd like to just find a hard top and be done with it but we'll have to see.

In the photo of the engine block the part that is leaking is above the hardline coming in and has 4 wires coming out of it.

Pics
1 At Reserve motor pool
2 A/C
3 Makes my deuce look tiny
4 In the drive
5 Leaky part


M923.jpg001.jpg002.jpg004.jpg005.jpg
 

bigbird1

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If they are AGM battery's get a charger made for them and charge them up slow, mine came back but were only two years old hawkers. I'll pm you the charger I got if you want. Post a want add for the primer pump, There have been a few bad engines guys are parting out. They aren't cheap new.
 
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mkcoen

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If they are AGM battery's get a charger made for them and charge them up slow, mine came back but were only two years old hawkers. I'll pm you the charger I got if you want. Post a want add for the primer pump, There have been a few bad engines guys are parting out. They aren't cheap new.
I'd appreciate the PM. These are delivery dated 2009 so would be at the end of their life cycle even if they hadn't been sitting for years but I'll try anything and could use a new charger anyway.

The part that is leaking is actually the fuel pressure transducer (just the top part with the wiring) and not the entire transfer pump. I'm hoping it's not that expensive but will try checking with someone that's parting one out as I need several other smaller parts.
 

Tornadogt

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I was told that the Fuel Pressure Transducer is for a Diagnostic tool that seems to not exists in the real world. I would say if you can remove it and plug the hole and never think about it again. You may be able to remove the soft top and take it to a Boat upholstery shop and have them resew it to the plastic trim if it is not to bridle. If you have two of the 4 batteries that will come back to life that's all you would need in our climate.
 

mkcoen

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Maybe if your lucky your alternator didn't kill itself trying to charge the dead batteries on your drive home, seems to be a common occurance after a slave off start.
We checked the alt once we got home and it was working fine.
 

mkcoen

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I was told that the Fuel Pressure Transducer is for a Diagnostic tool that seems to not exists in the real world. I would say if you can remove it and plug the hole and never think about it again. You may be able to remove the soft top and take it to a Boat upholstery shop and have them resew it to the plastic trim if it is not to bridle. If you have two of the 4 batteries that will come back to life that's all you would need in our climate.
That's kind of what I was thinking on the Transducer as the Parts TM shows it with a plug in it rather than the Transducer so will probably just cap it.

The plastic on the cab cover is broken in 3 places and pretty brittle so I think I'll need to replace the entire thing. I'll talk with you tomorrow about the guy in Killeen. Maybe he'll have a hard top coming through.

I'd like to see a schematic of just a 2 battery hook up. The way my luck goes if there's a 50/50 chance of getting something right I usually have 100% chance of getting it wrong. I'd really rather not fry the whole system hooking the batteries up incorrectly. If I could just get buy with purchasing a couple of new batts and doing that it'd beat buying 4.
 

SLOrazorsedge

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The plastic retainer slide was broken on one of my trucks in three places yet the soft top was in great condition. I took it to a top shop and he stitched if back together and aligned the broken plastic retainer slide for $20 bucks. It looks and worked out great :0)
 

Keith_J

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The -23 TM states the leaking fuel pressure transducer is a sign of flow resistance to the injection pump, either a slight plug in the lines or a filter that is clogged. I would suspect the filter after the priming pump is the issue.

Also, the transducer controls the electric priming pump which turns on with the master switch. If pressure is insufficient in the priming system, it runs until the camshaft driven priming pump can sustain. So by eliminating the transducer, the electric pump may not work. If you are running off only two batteries, this might be an issue.

The low speed of the cab heat blower is done by running off of only one battery, hence the small wires to the batteries. So yes, running off of only two is fine. Still don't know if there is an intake grid heater which could draw a good bit in cold weather.

And yes, had I taken my SECM up there, I could have pulled the transducer and plugged it with one of the 3/8 NPT pipe plugs I have in the back. And we would have had a slave port with two good batteries. :grd:
 
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mkcoen

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So it's raining today and I have a 1300 lunch appointment with other SS members so not getting a lot done. I did de-GL sticker the truck as well as scrap the tape residue off the driver's windshield (right in the line of sight of course). I also cleared the bumper numbers on the front of the truck. The rears were apparently painted over with a fairly hard enamel as I couldn't cut through it with xylene. The only other thing was to switch the battery charger over to a different battery. The 1st was at 13.5v when I unhooked it but we'll see if that was just a surface charge or if it holds.

My plan was to send all the info to CARNAC to get the trucks history but while I was looking for the registration number I came across the turn-in paperwork and found everything I needed. The truck was actually turned in by the TX National Guard in November of last year so it wasn't sitting in GL holding that long. But since the delivery date was 02/1991 and it only had 443 miles on it at turn-in it's been sitting idle at the NG motor pool for 23 years.

The turn-in checklist had pretty much the same line items that we found looking over the truck yesterday: left small mirror missing, will not start (fixed that one), 4 dead batteries, and left headlight. It did have a Class I leak at the transfer case listed but didn't list the leaking transducer (since it wouldn't start) or the cab cover (which wouldn't be readily noticeable unless driving).

The truck was assigned to C Btry 4th 133rd FA of the Texas National Guard - DUM SPIRAMUS TUEBIMUR (While We Breathe, We Shall Defend). So turns out that my new truck comes from the only Combat Arms area that I was never in (Infantry and Armor vet). I guess the truck and I together make the trifecta.
001.jpg002.jpg
 
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mkcoen

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A little more work this morning. Most of it involved driving around fetching stuff. I picked up 2 Series 31 Reconditioned batteries from Interstate ($40 ea + core). They don't fit as well as the 6TMFs but they fit and are low enough that the seat doesn't make contact with terminals. The only adjustments that have to be made are pulling the wood risers out and switching the slave receptacle cables over to the primary cable ends. This came in handy as the extra cables are a little longer so I used one of them for the NEG-POS connection.

I also picked up the new wiper blades from NAPA. I took some fine sand paper and scuffed the nice, shiny metal, taped the rubber, and set them aside to paint. It turns out I'm shy of flat black at the moment and it's really a little cool to paint any way.

After the batts were hooked up I went ahead and started it to make sure everything was working fine. I had disconnected the CTIS module in the hopes that it would reset but unfortunately it did not so on to further diagnostics (I'll be checking the lines with soapy water to see if there are any leaks). The truck started just fine, built air pressure in both tanks, oil pressure, and the alt meter was right where it's supposed to be. I still have the problem with the leaking fuel pressure transducer so it's next on the list. I let it run for a few minutes then shut it down.

Sitting with both air tanks full I can hear, but not feel, an air leak somewhere around the top of the brake pedal. I can't tell if it's coming from the brakes or maybe from the windshield wiper lines (still can't believe my 1971 M35 has electric wipers and my 1991 M923A2 has vacuum wipers). I'm letting it set for an hour or so and I'll check the bleed down from the air tanks to see how rapid a loss it is.
old wiper blades.jpg004.jpg006.jpg
 
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Warthog

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Mark, glad to see you got it home. It wasn't quite as adventurous as the Deuce recovery you and I made a few years ago. ;-)
 

mkcoen

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No dog bones to replace, that's for sure. However it may try my patience with it's complexity (not that I have much to begin with). It's a whole lot less daunting to look under the dash of a deuce than this beast.
 

mkcoen

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Also, the transducer controls the electric priming pump which turns on with the master switch. If pressure is insufficient in the priming system, it runs until the camshaft driven priming pump can sustain. So by eliminating the transducer, the electric pump may not work. If you are running off only two batteries, this might be an issue.
At this point I'd say we go that route to make it drivable. Since we're heading into the "OMG its HOT" time of the year I don't think it should be that much of an issue. That'll give me some more time to try and find one. I called Cummins today and they couldn't look it up based on the engine size alone. I can find it in the -24 schematics but not in the -24P where there might be a part number or NSN. The -24P only shows the pump with a plug and not one with the transducer.
 
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