Progress on rebuilding my M274A2 mule

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Mulemac02
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Progress on rebuilding my M274A2 mule

Post by Mulemac02 » Fri Apr 12, 2019 12:33 am

Thought you guys might like some pictures as I'm restoring my mule. I got the engine rebuilt and ready to install back into the mule when its ready. Next is me tearing into the transaxle to replace the seals leaking gear oil. Engine Serial number km000016
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Re: Progress on rebuilding my M274A2 mule

Post by RedArrow2016 » Fri Apr 12, 2019 12:55 am

Looks great and can't wait to see it all complete when that time comes here. Good to see that people are keeping history alive here...
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Re: Progress on rebuilding my M274A2 mule

Post by muleman7 » Fri Apr 12, 2019 6:20 pm

You stated Engine Serial number km000016

The top engine shroud is the thing most frequently disposed of when the military is stripping mules and any shroud will fit any AO42 engine.

TM 5-2805-213-14 7/69

Figure 3-17 Magneto Timing states:

"For model AO42-KM Engines with serial numbers lower than KM003275, turn magneto gear counterclockwise and position magneto gear timing mark two teeth from camshaft gear timing mark."

Most early KM engines had a hard mounted outlet vent valve to carb intake tube, mechanical hour meter and a fuel primer.

Yours has the rubber adapter that connects to the outlet vent valve, no mechanical hour meter or fuel primer.

I would set the mag and cam timing marks inline and start there. With the engine running the mag timing should be set to 18 degrees advanced.
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Re: Progress on rebuilding my M274A2 mule

Post by Mulemac02 » Fri Apr 12, 2019 6:42 pm

muleman7 wrote:You stated Engine Serial number km000016

The top engine shroud is the thing most frequently disposed of when the military is stripping mules and any shroud will fit any AO42 engine.

TM 5-2805-213-14 7/69

Figure 3-17 Magneto Timing states:

"For model AO42-KM Engines with serial numbers lower than KM003275, turn magneto gear counterclockwise and position magneto gear timing mark two teeth from camshaft gear timing mark."

Most early KM engines had a hard mounted outlet vent valve to carb intake tube, mechanical hour meter and a fuel primer.

Yours has the rubber adapter that connects to the outlet vent valve, no mechanical hour meter or fuel primer.

I would set the mag and cam timing marks inline and start there. With the engine running the mag timing should be set to 18 degrees advanced.
Just going off the cover and the engine data plate when I got the mule. And my mule serial number is BMY 00025. So that's the way it will stay. Because I got no other numbers to go off off. Do you have the parts or know of anyone that has them to make it look like an early kmengine?



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Last edited by Mulemac02 on Fri Apr 12, 2019 6:42 pm, edited 1 time in total.

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Re: Progress on rebuilding my M274A2 mule

Post by Mulemac02 » Sat Apr 13, 2019 12:39 am

But I'm going to find the timer and the proper stuff to make it look good. Theres a plug where the hour meter screws into.

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Re: Progress on rebuilding my M274A2 mule

Post by Mulemac02 » Wed Apr 17, 2019 11:53 pm

Update 4/16/19

Dismounted the left and right side drop axles on the transaxle today

Everything was going great till I seen the long axle shaft where the oil seal rides on the shaft... it was rust pits. I don't know if that makes a difference on sealing abilities.ImageImageImageImageImageImageImageImageImage

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Re: Progress on rebuilding my M274A2 mule

Post by muleman7 » Thu Apr 18, 2019 9:28 am

This is what I sent in an e-mail to you and post here for others interested. I welcome other opinions as we all learn from this board.

That is the area where the DG housing seal keeps gear lube inside the housing. The Black 1/8" line appears to be where the seal locates on the axle. There is not large amounts of gear lube that is forced against the seal. It only gets a little lube that splashes off the gear onto and through the bearing and then onto the seal lip.

I have seen a lot worse. I would sand the surface of the axle and install a new seal. They are neoprene and do a great job of keeping the lube in the DG housing.

I would pack the 205 bearing full of grease as it is only lubed as the gear splashes it. That will help keep lube from the seal lip.

The long axle shaft on the transmission goes through the clutch and input shaft area and that is the only place you do not want gear lube. Other than the brake shoes and on the ground.

The short axle shaft on the transmission goes directly into the ring gear that is bathed in lube.

The front end does not matter if either axle leaks because it goes directly to the ring and pinion gear that is bathed in lube.

Keep check on the lube level in the DG housings, trans and front end.

Short axle shafts are plentiful and reasonably priced. The long axle shafts are expensive.

If you decide to replace the axle shaft the gear is heated to install as it is a shrink fit as it endures a lot of torque. I have seen the gear split at the keyway. It is possible to press the gear on but must be aligned precisely to mate with the woodruff key. I would also install a new 205 bearing as they are reasonable in price. Most bearings have shields and I remove them and fill the bearing with grease. also pack grease so it will push against the seal.

Yes over time the grease may wash out of the bearing as long trips may cause the lube to warm and help soften and dilute. Short trips should not effect grease washout.

You could use a Redi or Speedi Sleeve.

Image

Pressing off the gear.

Image
Last edited by muleman7 on Fri Apr 19, 2019 11:10 am, edited 3 times in total.
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Re: Progress on rebuilding my M274A2 mule

Post by Mulemac02 » Thu Apr 18, 2019 10:57 am

Thanks muleman7 gives me ideas. Yes I did see your email. I just wanted to share pictures and progress with everyone. Your advice is great.

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Re: Progress on rebuilding my M274A2 mule

Post by dennispatterson » Fri Apr 19, 2019 1:59 pm

Many thanks Mulemac02 for your photos - they are helpful in my quest to rebuild my engine KM-004329 after a tear-down to clean out years of guck in the fins & shrouds. Could you help me with one rebuilding question? Do the slots in the magneto access shroud assembly 10919471 slide onto the 2 slotted rubber grommets MS35490-20 on the push rod housings? I should taken more photos before dismantling. Or, does the magneto shroud assembly sit adjacent to the rubber grommet rather than on top of it?

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Re: Progress on rebuilding my M274A2 mule

Post by muleman7 » Fri Apr 19, 2019 6:29 pm

Mulemac02

Yes the magneto shroud slides into the grooves in the rubber grommets then when in place it is held by a screw on the left hand flang that slides into the rubber groove.

I turn the gap of the left hand rubber grommet to 2 o'clock and the right grommet gap to 11o'clock so both gaps are in contact with the center of the grommet shroud. Plus the mag shroud slides into the tangs on the bottom of the grommet shroud. This takes finesse when assembling.

Make sure that the two flanges of the mag shroud are spread properly that slide easily into the grommet grooves without being too wide / loose.

Installing the shrouds that engage with the rubber grommets and connecting them together are one of the hardest assembly tasks. The shrouds should be as tight as possible to ensure proper cooling.

I leave the bottom of the shrouds below the blower as loose as possible usually using safety wire instead of the spring. I leave the bottom of the shrouds opposite the blower as loose as possible to allow maximum air flow. The cylinder at the blower gets plenty of air even with the shrouds tightened to maximum.
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Re: Progress on rebuilding my M274A2 mule

Post by Mulemac02 » Thu Apr 25, 2019 4:04 pm

Update 4-25-2019

Finished sand blasting the drop axle houseing.

Primed and painted the drop housings and transmission.

What does TC under the part number mean?
In last picture.ImageImageImageImage

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Re: Progress on rebuilding my M274A2 mule

Post by Mulemac02 » Sat May 11, 2019 12:42 am

Update 5-10-19


Started putting things back on the transaxle after a got a shipment from John

Installed John Emery's new transmission shift rail poppets didn't need it but gives peace of mind.

Installed a new transmission output shaft seal.

Also started to put back together the right side of the drop axle, and installed new oil seals everywhere. More work tomorrow. ImageImage

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Re: Progress on rebuilding my M274A2 mule

Post by Mulemac02 » Sat May 11, 2019 7:43 pm

Update 5-11-19

After sandblasting, primer and paint. final parts that need to go on the right side where installed today along with new seals, rubber o rings, and a new axle boot.

Will be starting on the left side in a couple of days.
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Re: Progress on rebuilding my M274A2 mule

Post by Mulemac02 » Tue May 14, 2019 6:46 pm

Put everything back together yesterday. ImageImageImageImageImageImageImageImageImage

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Re: Progress on rebuilding my M274A2 mule

Post by Grummanflyer » Tue May 21, 2019 6:24 pm

Very nice work.

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