New M274 mule owner

M274 Mechanical Mule Wanted, For Sale (NO AUCTION or EBAY), and Knowledge Base
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Auto Shop teacher
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Re: New M274 mule owner

Post by Auto Shop teacher » Sat Aug 02, 2014 8:55 pm

I am not all that familiar with mule carburetors, but almost all carburetors have a fixed main jet that regulates fuel delivery above about 1,500 rpm and is not adjustable. The air/fuel mixture is only adjustable in the idle circuit below say 1,100rpm. Do you feel 'normal' drag on the pull rope? There are two compression strokes every two turns of the crankshaft, so you will feel resistance as you pull through them. If you pull the rope with the spark plugs out of the engine, there should be hardly any resistance and it will be steady drag.

From what you said before the engine was "loosing power" so I am guessing that you are trying to rev it up. Bad fuel, low fuel delivery, (be sure you are getting a good squirt out of the fuel pump while you are cranking the engine over with the plugs out, I would guess something in the neighborhood of 3 to 4 psi is considered good), just disconnect the bigger fuel line at the carburetor to check, weak spark, timing off, clogged exhaust. Have you pulled the rocker covers and verified the rocker arms are all moving the same amount? I am getting into some less likely causes at the end of my list, but if you have checked fuel quality, fuel pressure, hot spark, correct timing, and compression, (95% of the cause of problems), the other items are possible.

Please remember I am throwing out common problems that affect most engines, so if some of our experts have some ideas, I would like to learn them too. :)


Chuck W.
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Re: New M274 mule owner

Post by Chuck W. » Sun Aug 03, 2014 9:08 am

If the carb is very old, put a new one on. 99% of mule engine problems are related to the carb. If you have the old "flat-top" fuel pump, replace it with a new "double-hump" style. And....you need to keep a couple fo extra pumps and carbs on hand, you'll need them again eventually, they just don't last very long!

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Re: New M274 mule owner

Post by cpearce » Sun Aug 03, 2014 1:26 pm

The carb is a year old but I'm not sure if the gas had ethanol in it when I was trying to start the engine a year ago. I put a new double hump fuel pump then too. Does the new airtex pump have the same issues with ethanol?

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Re: New M274 mule owner

Post by Chuck W. » Sun Aug 03, 2014 4:05 pm

You are probably O.K. with a year old pump and carb.

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Re: New M274 mule owner

Post by cpearce » Mon Aug 04, 2014 2:39 pm

Any ideas on what I'm going to need to fix after I get the engine running? Just trying to plan ahead since I'm not up there much.

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Re: New M274 mule owner

Post by Chuck W. » Mon Aug 04, 2014 6:02 pm

Need to check the transmission, front differential and drop axles and see if there is any oil in them, and take a magnet and stick up in the drain holes and check for metal. Make sure nobody has put grease in the drop axles, if you find grease, they will need to be torn down and cleaned, OIL ONLY in the drop axle housings!! Inspect the dust boots for leaks and cracks.

The list gets longer and longer. As you are going to find out, the mule is an expensive machine to own!

Replace axle nut retaining pins, replace lifting ring and outer hub O-rings. Replace inner wheel seals. Replace shift shaft seals. Replace transmission output shaft seals. Replace brake shoes. Replace front differential input shaft seal. Replace worn out tie rod ends. Rebuild steering box. On and on and on :)

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Re: New M274 mule owner

Post by cpearce » Fri Aug 08, 2014 9:02 am

Heres a few pics that I have and a video of it running:

Image

Image

Image

Image

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Re: New M274 mule owner

Post by Chuck W. » Fri Aug 08, 2014 9:37 am

Looking good! Glad to see another mule among the living!

In the photo of the rat's nest, it appears that your crankcase vent valve is in the closed position.
Image

In the video, I see the temp gas tank straped onto the rear, but I only see one hose going to it, where is your fuel return line? Don't plug the return line or you will fill the engine full of fuel.
Last edited by Chuck W. on Fri Aug 08, 2014 9:45 am, edited 1 time in total.

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Re: New M274 mule owner

Post by cpearce » Fri Aug 08, 2014 9:41 am

The valve that is connected to the tube in front of the carb? Do you always want that valve and the one into the air filter always open? When would you close them?

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Re: New M274 mule owner

Post by Chuck W. » Fri Aug 08, 2014 9:47 am

Yes, keep them open. The only time they are closed is when the mule is turned onto it's side for maintenance. When closed while running, you will have excessive crankcase pressure and can cause CC seals, etc. to leak.

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Re: New M274 mule owner

Post by cpearce » Sun Aug 10, 2014 9:09 pm

If it grinds shifting into gears does that mean i need to rebuild the tranny at some point?.

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Re: New M274 mule owner

Post by Chuck W. » Mon Aug 11, 2014 12:37 pm

Make sure your clutch is releasing fully.

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Re: New M274 mule owner

Post by Auto Shop teacher » Mon Aug 11, 2014 2:14 pm

Chuck since the trans is non syncro, does it help to double clutch shifting gears, or just pause a moment in neutral?

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Re: New M274 mule owner

Post by Chuck W. » Mon Aug 11, 2014 4:55 pm

I don't think it's a good idea to try to shift from 1st to 2nd at any kind of speed anyway. If you want to be in 2nd, start out in 2nd. They are not hot rods, they are 40-50 years old and need to be treated easy. If you are trying to shift from 1st to 2nd like driving a car, you will grind the gears every time. I've seen a lot of screwed up syncro blocking rings from guys trying to "speed shift" from 1st to 2nd.

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Re: New M274 mule owner

Post by cpearce » Mon Aug 11, 2014 8:51 pm

Wheres a good place to get a shifter knob oem or not?


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