Swamp Buggy

A place to post pics and descriptions of ongoing restoration projects

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Re: Swamp Buggy

Unread post by Surveyor » January 31st, 2016, 5:16 pm

Will do. I didn't put transmission fluid but I did put Marvel Mystery Oil.
1960 M151 Run #1
"There is one nut on a M151 that is very difficult to remove....." - K8icu
"She ain't a Cadillac and she ain't a Rolls, But there ain't nothin' wrong with the radio" - Aaron Tippin
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Re: Swamp Buggy

Unread post by rickf » January 31st, 2016, 6:20 pm

Even better. :mrgreen:
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: Swamp Buggy

Unread post by Surveyor » January 31st, 2016, 10:41 pm

As always thanks for the advice Rick. Lesson of the day - I should have measured compression on each cylinder before I messed with the valve clearance. First time I've ever tried messing with valves like this. Read the manual and looked at some posts about doing it when not running and gave it a shot. Then measured compression after. 90-30-90-60. Not sure what it was before and 2 and 4 was where I made the most adjustments . I doubt I turned any of the adjusters more than 2 rev. Could #2 be bad clearance or is that so far down that I'm looking at a valve or ring problem? The TM gives a 135 to 145 but this site http://armyordnance.tpub.com/OD1001/OD10010092.htm says 85psi or higher. What should I be striving for?

Will try again in a couple of weeks... next week starts the Mardi Gras season!
1960 M151 Run #1
"There is one nut on a M151 that is very difficult to remove....." - K8icu
"She ain't a Cadillac and she ain't a Rolls, But there ain't nothin' wrong with the radio" - Aaron Tippin
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Re: Swamp Buggy

Unread post by rickf » February 1st, 2016, 11:20 am

Are you sure you adjusted the valves at top dead center on the compression stroke of that cylinder? You can't adjust them all on TDC of number one on the timing mark. Put some oil in each plug hole and see if it brings up the readings. Be sure the throttle is held wide open throughout the entire test. The 30lbs. is definitely bad but so is the 60 so more checking is in order.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: Swamp Buggy

Unread post by Surveyor » February 1st, 2016, 11:44 am

Just think I figured out what I did wrong after rereading a post you made about this on the 503. I'll give it another go soon and see what happens.
1960 M151 Run #1
"There is one nut on a M151 that is very difficult to remove....." - K8icu
"She ain't a Cadillac and she ain't a Rolls, But there ain't nothin' wrong with the radio" - Aaron Tippin
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Re: Swamp Buggy

Unread post by Surveyor » February 7th, 2016, 8:23 pm

Well I took another pass over the clearance the right way this time and they all checked almost exactly as before on psi. Got it right the 1st time by luck I guess. I then tried the oil as rick suggested and compression jumped to 100, 60, 100, 90. About 30psi in each "bad" one. I'm guessing she may start once I have new plugs but she might be mistaken for the misquito control truck. Panel reads 65,000 miles. If true, I'm sure they were very gentle. :roll:
1960 M151 Run #1
"There is one nut on a M151 that is very difficult to remove....." - K8icu
"She ain't a Cadillac and she ain't a Rolls, But there ain't nothin' wrong with the radio" - Aaron Tippin
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Re: Swamp Buggy

Unread post by rickf » February 8th, 2016, 11:55 am

So, at this point I would say you have one bad cylinder and one borderline cylinder. If you have access to a cylinder leakdown tester now would be the time to use it and find out where the compression is going in that cylinder. To those that do not know what a leakdown tester is, it applies a metered amount of air at low pressure to the cylinder at TDC on the compression stroke of that cylinder. It checks to see how much of the air going in is leaking out and shows that on a second gauge as a percentage of leakage. If you take off the oil fill cap, the radiator cap and the air cleaner you can listen at each point and look for bubbles in the coolant. You will hear air in the carb, if it is and intake valve leaking. You will hear air in the exhaust if it is a burnt exhaust valve. You will hear air in the oil fill cap if it is bad rings or broken piston. You will see bubbles in the radiator if it is a blown head gasket or cracked block.

This is why you always see me harping on a leakdown test after a compression test. It will tell you a LOT about the engine. You can get leakdown testers for under 50 bucks in a lot of places. Well worth it in my book.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: Swamp Buggy

Unread post by Surveyor » February 8th, 2016, 3:30 pm

If I'm not worried about the numbers and just want to find the source of the problem would this work? Could I just hook up a pancake compressor to the quick connect of the short hose that came with the compression tester?

I'd set the regulator on the 125psi compressor to about 40psi. Let it fill up, quickly connect the short hose already screwed in to the plug hole with the quick connect, and finally listen for/find the leak as suggested. Repeat as needed. I wouldn't need to keep the engine from turning since the trans is still locked up.

Or am I missing something?
1960 M151 Run #1
"There is one nut on a M151 that is very difficult to remove....." - K8icu
"She ain't a Cadillac and she ain't a Rolls, But there ain't nothin' wrong with the radio" - Aaron Tippin
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Re: Swamp Buggy

Unread post by rickf » February 8th, 2016, 10:06 pm

That would work but make sure it is at TDC of the compression stroke on the cylinder you are testing and drop the pressure lower if you can. Turn the compressor on and then turn it off at 30 lbs and start there. You will always hear a little bit of air coming past the rings in the oil fill but if you hear air flow then that is a problem.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: Swamp Buggy

Unread post by Surveyor » February 9th, 2016, 2:54 pm

Not the best Mardi Gras I ever had. Almost figured out why it's been sitting so long. Got everything setup to do the test. Filled the radiator with water and found a small leak on the bottom left of it. Then I saw this coming out of the bell housing as the hose was still running... :cry: :cry: :cry: When I drained the original oil awhile back I didn't notice anything wrong other than it looking well used. Maybe it's just a freeze plug. :| :?: Looks like it's time to pull it out.

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1960 M151 Run #1
"There is one nut on a M151 that is very difficult to remove....." - K8icu
"She ain't a Cadillac and she ain't a Rolls, But there ain't nothin' wrong with the radio" - Aaron Tippin
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Re: Swamp Buggy

Unread post by rickf » February 9th, 2016, 3:30 pm

Yup, Not at all uncommon for those two freeze plugs to rot out. This also a good time to pull the head and see what you really have going on. You can do that leakdown test before you pull it to give any clues what to look for first though.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: Swamp Buggy

Unread post by Mr. Recovery » February 9th, 2016, 3:32 pm

There is a freeze plug on the back of the block, if I remember right all the "block" plugs are the same size.

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1960 M151 Run 1
1963 M151 Willys DoD 10-63 in Baltimore
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Re: Swamp Buggy

Unread post by rickf » February 9th, 2016, 5:40 pm

I don't know why I was thinking two? I guess I was thinking the cam plug also. Anyway, that will be where the water is coming from back there. Thanks Dan.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Re: Swamp Buggy

Unread post by kmam » February 9th, 2016, 6:07 pm

I gather what you call a freeze plug is what we call a welch plug. My understanding is that they are a result of the block casting process, not sure where the freeze name comes from?

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Re: Swamp Buggy

Unread post by halftracknut » February 9th, 2016, 6:24 pm

Park your jeep with water or weak anti freeze in the block on a cold night and you will find out why we call them freeze plugs.... :lol: :lol:
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