New M274 mule owner

M274 Mechanical Mule Wanted, For Sale (NO AUCTION or EBAY), and Knowledge Base
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cpearce
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New M274 mule owner

Post by cpearce » Fri Aug 02, 2013 7:23 am

I recently inherited my grandpas old M274 mule. It has not started for years, so I am trying to rebuild it. I replaced the carb, fuel pump, and spark plugs and could only get one side to fire. I finally took it apart and one of the pistons had shattered (dont have a compression gauge). Before I get too deep into taking it apart, I wanted to see if anyone had some pointers? I have the manuals and I am taking pictures as I go. When it was running it leaked oil everywhere. Can I make my own gaskets or should I find a place that sells them?

The engine is the A042 2cyl

Thanks,
Cody


Chuck W.
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Re: New M274 mule owner

Post by Chuck W. » Fri Aug 02, 2013 9:43 am

Contact John Emery at Emery Mule Supply for parts and gaskets. (262) 567-5606
If you just need a piston & jug, I may have one. It will need new rings for sure.
Be carefull of the gasket kits sold on e-bay, most are for the gen set version.

cpearce
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Re: New M274 mule owner

Post by cpearce » Fri Aug 02, 2013 11:04 am

I already bought the gasket set from ebay before knowing what I needed :(. However, I did get a good deal on the pistons/cylinders from ebay.

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Re: New M274 mule owner

Post by Austringer » Fri Aug 02, 2013 7:56 pm

Which model engine, 2 or 4 cylinder, you mentioned a M274 which would be a 4 banger.
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Chuck W.
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Re: New M274 mule owner

Post by Chuck W. » Sat Aug 03, 2013 6:50 am

2 cylinder

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Re: New M274 mule owner

Post by cpearce » Mon Aug 05, 2013 11:01 am

I took apart the second cylinder head last night and it is in pretty bad shape. One of the valve rings won't even seat anymore. Is it worth taking these apart to clean the valves or should I just get two new cylinder heads? What tool do you use to take the valves off? I used a C-Clamp on one and it was a pita.

Thanks,
Cody

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Re: New M274 mule owner

Post by Chuck W. » Mon Aug 05, 2013 4:10 pm

Cody, you can purchase new heads for less than you can rebuild those, from the sound of the damage. You might even conside finding a new AO-42 gen set engine and swap it over. New gen set engines are available for about $550 from several surplus dealers.

All that said, if you want to rebuild your engine, you might take your heads to a local small engine repair shop or motocycle shop, they should be able to repair the valve seats and grind the valves.

You will need a copy of the engine manuals: TM 9-2805-213-24P and TM 9-2805-213-14

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Re: New M274 mule owner

Post by cpearce » Tue Aug 06, 2013 12:00 pm

What is a genset engine and what was it used for? I'd like to try and rebuild the heads myself even if I have to buy a tool. Any ideas on what the substitute would be for the keepers? I'd like to try and rebuild the whole engine without the genset. Is there any part of the engine you would not dissassemble?

I found out that one of the engines big oil leakages was that the rubber gasket was missing from the cylinder head. The one that allows you to get to one of the nuts that bolts on the cylinder head and cylinder.

Any suggestions on what parts I should bead blast and what ones to pressure wash?

I have all of the manuals on CD.

Thanks,
Cody

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Re: New M274 mule owner

Post by Chuck W. » Tue Aug 06, 2013 3:18 pm

The AO-42 engine is a Military Standard engine that was used in several applications, including the 5KW generator sets and the M274A2 through A5 mules. New generator set engines are readily available and can easily be configured for the mule application as long as you have a donor mule engine to supply all the unique mule parts.

The AO42 engine is pretty tough, and I rarely replace more than the cylinder and piston assemblies and the heads. Usually, there's no need to split the crankcase. If you already have a new set of piston & cylinder assemblies, I'd call John Emery and see if he still has NOS heads. At one time, complete heads were available for around $35 each, that's probably cheaper than you could have your heads rebuilt.

Be very careful about bead blasting, you don't want to take any chances introducing blasting media into the engine. Mineral spirits and a good, stiff brush is the best way to clean engine parts. Save the bead blasting for the tins and other exteral parts.

If you have the TM's, then you have all the info you need to repair the engine. Good luck and keep us posted here on the G.

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Re: New M274 mule owner

Post by cpearce » Thu Aug 08, 2013 2:30 pm

I bought one new head and gasket overhaul set. I'm hoping the other head is still good. I took apart the bad one and one of the valves was bent!

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Re: New M274 mule owner

Post by cpearce » Mon Aug 12, 2013 6:21 am

A couple more questions. The screen and the sheet metal that holds it, in the engine, are damaged beyond repair. Are these critical components and do I need to replace them? I bought a new head, but it didn't come with the rubber hole seal and the piece that holds it. Does someone sell these?

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Re: New M274 mule owner

Post by Chuck W. » Mon Aug 12, 2013 7:15 am

I'm not sure what screen you are talking about, need more info. ALL the cooling shrouds must be in place to provide necessary cooling air, especially to the left side. Running without the top shroud will lead to overheating and can cause the left piston to seize.
As far as the head plugs, there is a new style plug that does not require the metal retainer, and should be in your gasket kit along with the push rod tube seals. It is orange, and has a raised ridge around the outside, it simply pops into the hole in the head. I like to use a little Indian Head gasket sealer on the plug.

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Re: New M274 mule owner

Post by cpearce » Mon Aug 12, 2013 8:16 am

The screen is the strainer in the oil pan. And the sheet metal is also in the oil pan.

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Re: New M274 mule owner

Post by Chuck W. » Mon Aug 12, 2013 1:16 pm

If you are talking about the windage tray, the piece that goes between the oil pan and the block, and the oil pump pickup assembly, YES! These are critical parts! How in the world did these get damaged? Sounds like you have a lot more going on with this engine than just a damaged piston....sounds like a rod got loose..

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Re: New M274 mule owner

Post by cpearce » Mon Aug 12, 2013 7:06 pm

The windage tray is not damaged. Yes, the piston shattered and destroyed the bottom circle. There's also a piece of sheet metal that is not in the picture below. Ill take a picture tomorrow.


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