2AO-42 Gen Set to mule conversion

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Chuck W.
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2AO-42 Gen Set to mule conversion

Post by Chuck W. » Tue Jul 25, 2023 11:27 am

I have 2 gen set-to-mule engine conversions to do this fall. Since these engines will be built-up for spares, there is no big rush to have them completed. I am thinking about taking the time to do a thorough photo documentation of the process. The documentation that I have shared in the past was quick and incomplete because there was a rush to get the mule back in service.
My question is, is this something people here would be interested in seeing, and would you rather have a step-by-step photo journal or a you-tube movie?
Thanks.


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Re: 2AO-42 Gen Set to mule conversion

Post by nw5s » Tue Jul 25, 2023 4:31 pm

I’d love to see you document a genset conversion. Either method of documentation you propose is fine by me.
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ltsimp
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Re: 2AO-42 Gen Set to mule conversion

Post by ltsimp » Wed Jul 26, 2023 4:28 am

Chuck, either format would be great, however I would prefer a step by step version. The you tube video I think, would require a lot of stopping and starting of the video while working on the conversion. Thank you in advance.

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Re: 2AO-42 Gen Set to mule conversion

Post by tbied2 » Thu Jul 27, 2023 8:36 pm

.... i have done one myself & it is fairly easy. the hardest problem i had was getting the fly wheel off of the generator engine. that bolt was tight. also after installing in my mule.. one of the push rod tube "O" ring seals was no good so had to dissassemble that after a day or two of running. and finally.. are you going to swap the camshaft & rocker arms to get the engine up to the original mule engines horsepower...??

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Re: 2AO-42 Gen Set to mule conversion

Post by Chuck W. » Sat Jul 29, 2023 8:26 pm

are you going to swap the camshaft & rocker arms to get the engine up to the original mule engines horsepower.
I'll refer you to the late Charles Witt's excellent post on the differences between the AO-42 and 2AO-42 engines viewtopic.php?f=148&t=262382, the camshaft, rocker arms and push rods are all the same, the difference is in the length of the valve stems, the use of head spacers and the piston rings. Here's Charle's spreadsheet showing the part numbers
Image
As far as the different HP ratings, I'll quote Charles:
I discussed the differences in Horse Power ratings 10 Hp for the 2AO42 Power Plant and 14 HP for the AO42 Mule with an engineer. His explanation was the Power Plant had to be rated for 100% usable HP since it is figured at a constant load and RPM. Thus the manufactures could fit the correct engine to a generator, water pump or Etc and qualify it to operate under constant load. The Mule ran at varying loads and RPMs and its Max HP is listed. His conclusion was the mule could not deliver 14 HP constantly and survive.

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Re: 2AO-42 Gen Set to mule conversion

Post by Conibear » Mon Oct 30, 2023 12:15 pm

Either method of documentation of a genset swap would be great!
M274 with 4 cyl first series engine

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Re: 2AO-42 Gen Set to mule conversion

Post by iVelociraptor » Sat May 04, 2024 5:42 pm

Any updates on this? Recently acquired a genset engine and I'm curious as to how involved the conversion is.

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Re: 2AO-42 Gen Set to mule conversion

Post by Guam0311 » Sun May 05, 2024 9:42 am

I did a Genset engine swap as well. I found this and it helped guide me through some steps. I found this a few years back on "steel soldiers". The guy has some useful information that will help. Have your parts list manuals and your engine manuals available and you will be ok. also take a lot of pictures for they will help.

I have a complete set of Technical Manuals for the Mule in paper form – and some manuals on my computer. The paper copies are much easier to use during the operation, as it is faster to find information by flipping the pages and you don’t get grease all over your computer keyboard.

The following list of manuals should be considered the bare minimum for this operation. I did discover that there are some inaccuracies between what was in front of me at the time and what the book said – most likely due to the TM date.
TM 9-2320-246-20, Organizational Maintenance (Engine removal)
TM 9-2320-246-20P, Organizational Maintenance Parts (Parts identification)
TM 5-2805-213-14, Operator/Direct/General Support Maintenance for the AO42 Military Standard Engine (Everything about the engine)
TM 5-2805-213-24P, Organizational / Direct / General Support Parts for the AO42 Military Standard Engine (Parts identification)

I am sure I also used this list of manuals – just not as much as the above list. If you don’t have a complete set of the manuals for your Mule, you should get them – you know, just so you have them.
LO 9-2320-246-12, Lubrication Order
TM 9-2320-246-10, Operator’s Manual
TM 9-2320-246-34, Direct / General Support Maintenance
TM 9-2320-246-34P, Direct / General Support Parts (Parts identification)

Common tools needed – screwdrivers, pliers, set of 1/4” to 7/8” combination wrenches, 3/8” socket set, 1/2” ratchet and socket for crankshaft pulley (15/16” socket) and spark plugs (7/8” x 2 3/8” depth) – (This socket might be hard to locate. None of the five suppliers in town had one.), come-a-long hoist, 3/8” eye bolt (There is a threaded hole in the top of the block. This eye bolt will thread into the hole and allow you to hook the come-a-long to the engine.), clutch / pressure plate alignment tool (Small diameter of .620” for a length of .765”, next diameter of .750” for a length of 1.540”, then enough length for a “hand hold”. I made this tool myself. If you need to use it, please let me know, and I will get it to you.).
DSCN1527.jpg

Use a two prong gear puller to remove crankshaft pulley. Be careful! This is a cast iron pulley and easy to break. Luckily mine was “pre-broken”, so all I had to do was find another one. It had been brazed together at the spokes, but the run out was severe enough to require replacement. I fabricated a puller to remove flywheel, as the smaller two prong puller was not long enough. This was really nothing more than a 1/2” thick by approximately 2” wide by approximately 24” long piece of flat steel. Drill a hole in each end to match the appropriate threaded holes in the flywheel and another hole in the center. Use a bolt with a nut on the bottom side and tighten the bolt to remove the flywheel. A 1/2” impact wrench was needed to remove the crank pulley and flywheel. I used my propane torch to apply heat to some of the more stubborn fasteners. They came right off after that. I thought I needed a torque wrench, but did not.

I dropped the engine down from Mule. There is no need to lift the Mule to remove the engine. No need for jack stands. I had some years ago, but can no longer locate them. I bought a set of four – and they are still brand spanking new. I suppose I will try and keep track of them, but I really don’t like crawling around under vehicles much anymore.

I did discover that one “leg” of the upper air cleaner housing was broken. Luckily, the part was still bolted to the bottom of the bed and after short a trip to the machine shop, the part was welded together again. I only broke one bolt during the entire operation. A bolt in the timing gear cover twisted off, as I was removing the cover. Since this was in the original Mule engine, this was not a problem. The 3/8” socket set lessens the probability of twisting off bolts, but it is much easier to allow a bolt to soak and perhaps use some heat then it is to remove a broken bolt from aluminum.

I used two engine stands. The Generator Set engine without a bell housing is placed on one stand to disassemble. I used the second stand to disassemble the original Mule engine. Once the original Mule engine is disassembled, remove it from stand. Remove the bell housing from original Mule engine and install it on the Generator Set engine. Build the Generator Set engine – with the installed bell housing – on the stand. Sure, you can do it with only one stand. I am just describing the way I did it – plus the jack stands, torque wrench, and engine stand makes a nice package of stuff I probably won’t ever use again. I did return the second engine stand from the guy I borrowed it from.

Make a list and take photos of each part removed from original Mule engine. Place parts with hardware in order. Reinstall in reverse order. Engine shrouds are confusing. Remember to use your layout order and disassembly list. I will cover this later.

As gaskets are identified from gasket set (Use section IV of TM 5-2805-213-24P), place them with the parts to be reinstalled. NSN for gasket set is – 2805-00-984-4765, Kit, Engine Gasket. You will have many gaskets in set you will not use. Don’t throw them out. Spare parts are good. The oil pan spacer and oil pan gaskets are not included in the gasket set and must be fabricated. I used common “gasket material” for the spacer and a “rubber/cork” gasket material for oil pan. You will also need to make gaskets for carburetor and air intake manifolds from the same “gasket material”. I constructed gaskets for the exhaust gas bypass tubes to air intake manifold from copper pipe. I used some 2” copper pipe that I had laying around. I have hot water heat in my house and have had to make some changes from time-to-time. Anyway, I used about 4 inches of the pipe. Cut it down one side. Anneal it with your torch (hot torch then cold water) to soften it. Flatten it out. Cut some parts out that look like gaskets. Yes, I know sounds like a pretty neat trick. Sorry I did not get any photos. This was an idea from my Brother-in-Law, so if it doesn’t work, he gets the blame. Of course, if it does work – well, he doesn’t read this forum. The Generator Set engine has a “new” seal in timing gear cover. Remove it and reuse it in original Mule engine timing cover. Use TFE (Teflon) paste pipe thread compound on block oil line adapter fittings and plugs. Do not over tighten any fittings! Remember Teflon acts as a lubricant, so things can get tight pretty quick.

I used the larger governor oil line from the Generator Set engine. I could not remove fitting from original Mule engine for the smaller line. It works fine and more is better, right?

I used the spin-on oil filter bracket from Generator Set engine and saved the original parts of the canister oil filter. The spin-on filter will be a Fram PH8A filter. I added 2 3/8 quarts SAE 30w oil and 1/8 quart (4 ounces) of Marvel Mystery Oil.

I was able to find the following parts - Fan belt (NAPA 3VX350), Fuel filters – (NAPA 3034), and Clutch Throw-out bearing (NAPA N1054) at my local auto parts store. I used the new style fuel pump already installed on the Generator Set engine and kept my original “flat top” style (which worked, when I removed it) for spare parts. The Generator Set engine has new connector hoses for your intake manifold to intake manifold elbow assemblies. Don’t throw them out. Spare parts are good.

Engine paint color was Krylon Camouflage Ultra Flat #4293 Olive (SKU 2450404293) from Ace Hardware. This is not the correct color for my engine, but I knew that hardly anybody on Steel Soldiers worries about the correct color of paint. roflBesides, I did a search and could not find any information on paint colors. :grin:

I removed data plate from top shroud in order to repaint the shroud. The data plate is fastened with “pop rivets”, which are easily removed and then replaced after painting. I thought this was easier than masking the plate. All parts were wire brushed before painting.

Once your new Mule engine is running, you will have a rather large pile of Generator Set engine parts. It seems to me that some of these parts might be usable to someone, but not your Mule. Well, there might be a couple of parts yet to be installed on the Mule. My Brother-in-Law has another idea – not sure how it will work – or even if it will ever be anything other than an idea. It sounds like a cool idea. If we can get it going, I will post information. Think charging system.


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