M151 Timing chain and gears

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
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Kurt Lesser
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M151 Timing chain and gears

Post by Kurt Lesser » Sat Oct 22, 2022 9:31 am

I apologize in advance if this has been asked a hundred times already but does anyone know if the timing chain and gears have a commercial equivalent or know of anyone that has them available?

TIA
Kurt Lesser
US Navy, 1969-1975
M996A1 Ambulance w/M101A3 Trailer
M274A2 Mule
M151A1 Mutt w/M416B1 Trailer
M890 Crew cab


Rickf
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Re: M151 Timing chain and gears

Post by Rickf » Sat Oct 22, 2022 1:46 pm

No timing chain, crank gear and cam gear.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: M151 Timing chain and gears

Post by Kurt Lesser » Sun Oct 23, 2022 10:12 am

Thanks Rick. I was using my 151 to move my 101 trailer around when I heard a bang and it started smoking and running very rough. I thought it might have been due to a timing chain slippage but now I see that probably didn't happen. Pulled the plugs and they were oil fowled so I cleaned them but it didn't help so I replaced them and haven't had a chance to see if that did anything. This evening I pulled the valve cover and everything there looks normal. No broken springs or bent pushrods. I ran a compression check and they all came in around 120 psi so where do I go now? Pull the pack and drop the pan? Could this be a broken crank problem? The clutch and trans still feel normal. Any suggestions would be appreciated.
Kurt Lesser
US Navy, 1969-1975
M996A1 Ambulance w/M101A3 Trailer
M274A2 Mule
M151A1 Mutt w/M416B1 Trailer
M890 Crew cab

Rickf
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Re: M151 Timing chain and gears

Post by Rickf » Sun Oct 23, 2022 10:32 am

Broken crank will seldom run afterwards, did this sound like a mechanical sound or a backfire? Is the smoke black or blue? Good compression leads me to believe that the engine is mechanically good. If the smoke is blue or white does it have a sweet smell? That would be antifreeze and indicate a blown head gasket. Clean plugs and good compression would lead me to doubt that issue. I am leaning towards possibility that the timing advance in the distributor is either gummed up or broke a spring. Take a timing light and check your base timing at idle and it should be right on the timing mark. If it is not and it was running good before do not move it yet, with the light on the mark rev it up and see if the mark moves smoothly up and then smoothly back again. If it does not then you will have to pull the distributor apart. The easiest way to do this is on the bench. Take the cap off and crank the engine around until the rotor is pointing at number one plug wire, basically almost in line with the engine but angled in just a hair towards the front of the block. Then loosen the clamp down at the block, remove the vacuum lines and power wire and pull it out. It will only go back one way but as long as you do not turn the engine over the rotor reference make it real easy.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: M151 Timing chain and gears

Post by Kurt Lesser » Sun Oct 23, 2022 6:08 pm

Looks like a busy day tomorrow! Thanks Rick.

The sound was a low pitched mechanical sound and the smoke I'm seeing is bluish. I didn't check the smoke for smell but wouldn't a coolant issue drop the compression?
Kurt Lesser
US Navy, 1969-1975
M996A1 Ambulance w/M101A3 Trailer
M274A2 Mule
M151A1 Mutt w/M416B1 Trailer
M890 Crew cab

Rickf
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Re: M151 Timing chain and gears

Post by Rickf » Mon Oct 24, 2022 5:22 am

Yes it would so I am a bit stumped on the oil smoke. For oil to get into the cylinder it has to go past the rings, past the valve seals or worst case a cracked block or broken piston. But for any of these scenarios to happen instantly associated with a bang usually means broken parts and it is not sounding like that to me. Broken parts will definitely affect compression. A more accurate test is a leak down test, you can buy a tester at Harbor freight pretty cheap. But I am not sure that will help just yet. Check that timing and see what it looks like and we will go from there. I wish you were near me, I love a challenge! But it is much easier to diagnose in person than it is on the internet. this may end up as a phone call to make it a little more real time.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: M151 Timing chain and gears

Post by muttguru » Mon Oct 24, 2022 1:48 pm

Hello Kurt,

just to add what Rick has already suggested. And they don't involve any big dismantling operation.
1. Check the state of the ignition coil. The shiny-chrome-finish Chinese coils are notorious for blowing apart. Wear rubber gloves when you pull the distrib-cap off.
2. Check the fuel pump. If the diaphragm has ruptured, raw fuel will get into the oil immediately and you will experience blue smoke pretty quickly afterwards.

Ken
Contact address - muttguru@aol.com
Always wanted - Details and pictures of M416 Trailer data plates & M151 data plates & body-tags for my research. Thanks!

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Re: M151 Timing chain and gears

Post by Rickf » Mon Oct 24, 2022 4:34 pm

Ken has a couple of good points. You will eventually be pulling the distributor cap off anyway so you will get a good look at the coil. All the ones I have seen that blew up quit right then and there. I thought about the pump but the bang had me wondering. I am now wondering if the bang may not have been from the trailer hitch, the trailer on the hitch with the pintle hook and ball will bake a lot of mechanical banging. Maybe just coincidence that the engine started running rough at the same time. If the fuel pump went bad it would not only put gas in the oil but it will also fill the air cleaner with gasoline through the fording vent on the pump. I have a couple of ideas but I wanted to run the easiest and cheapest by first.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Kurt Lesser
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Re: M151 Timing chain and gears

Post by Kurt Lesser » Sat Oct 29, 2022 6:15 pm

Ken ans Rick, Thanks for all of your inputs. Today I was able to get back into the engine and managed to locate the problems (2). The "bang" I heard was the front plate of the alternator breaking at the mounting point. I'm not sure if it was just coincidence or not but at the same time the accel pump diaphragm let go dumping gas into the carb. At the very least I now know the engine is spotless inside, the oil and filter have been changed, the plugs are new and the distributor has a nice new paint job. The carb came off and went thru a major cleaning and I found another accel diaphragm (didn't have a new one) and installed it. Checked the timing and she fired right up!
Kurt Lesser
US Navy, 1969-1975
M996A1 Ambulance w/M101A3 Trailer
M274A2 Mule
M151A1 Mutt w/M416B1 Trailer
M890 Crew cab

Rickf
G-Lieutenant General
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Posts: 5911
Joined: Sun Mar 19, 2006 10:04 am
Location: Pemberton, New Jersey

Re: M151 Timing chain and gears

Post by Rickf » Sun Oct 30, 2022 5:21 am

Glad to hear you found the problem. A broken accelerator pump diaphragm would produce black smoke from running extra rich. That is where I was being thrown off track.

It is always good when someone comes back with the final solution to the problem. This can be a big help to people looking things like this up in the future.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone


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