Mutt quitted working

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Mutt quitted working

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Mutt quitted working

Postby dr. trinkmann » October 20th, 2017, 9:15 pm

She quitted working under load last sungday.
Accerlerating under load (4th gear over 50mls/hr) or hill-climbing she bocked up, stumbled...and so on ...the old story.
Additionally added 'after markert fuel filter' got clogged after 1 1/2 driving season. Swapped this filter today and she ran like new!
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Re: Mutt quitted working

Postby Fil Bonica » October 20th, 2017, 9:40 pm

Not an unusual problem.
I would plan on inspecting and cleaning gas tank:

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Re: Mutt quitted working

Postby UDTDave » October 22nd, 2017, 8:02 pm

Same problem. Mine sputtered on and off 1 mile from the house. I got it back and the fuel filter was nearly completely blocked. Got a see through filter with replaceable filters. Runs great now. Love the easy fixes.
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Re: Mutt quitted working

Postby rickf » October 23rd, 2017, 8:25 am

Careful with those replaceable filter types, I ran into a situation with one of them and it sounded all the world like it was running out of gas but we just put the new filter in. So we replaced the coil. Did not solve the problem. Luckily the guy made it home after a long ride and the next day I went and looked at it and the new replacement type filter was clogged. It looked perfectly clean. We threw that one in the trash and used the good old parts store plastic Fram filter and never had another problem. And the Fram's cost 1/4 as much! By the way, that is the only Fram filter I will use, never the oil filters. Another whole story there.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: Mutt quitted working

Postby dr. trinkmann » October 23rd, 2017, 6:30 pm

Fil, you're right. Actually installed tank is (inside) in bad condition. Replacement tank is already here and waiting for installation. Maybe I will do that in coming spring.

Rick, I don't understand your answer completely...maybe because english is not my native language. I added - like somewhere here it was adviced - an additional civilian (plastic, with paper filter element inside) directly before the original metal-filter which is installed in the carb.

Before I realized the clogged Filter I recognized a more and more coming up backfire when rolling downhill or without throttle. What I found was a blown gasket between outlet manifold and first exhaust tube. That gasket was blown because both brass (!?) nuts were bad in threats. Luckily found two (steel) nuts in stock and a new gasket. Backfireing eliminated for this time!

After exchange of the filter I checked the timing, which was quite a little bit early. Fixed that, too.
Dwell was just inside recommended range, but I'm planning to set up a second Ignitor with swiss controls during this winter and change from points to solid state with next spring.

Most interresting thing:

I was not able to set up the carb as recommended:

Turning the idle mixture screw completely in gives the highest revs.
Turning out about max. 1/2 turn leaves the rpm at same level. Then, while continuing turning outside she will continuously rev down until dieing.
I setted the mixture screw at the level when she slowly revs down and another bit more outside. Then I reved up with idle speed screew to reach about 670-700 rpm.
How should I set up that carb (overhauled by myself in 2015 with big carb-kit, unfortunatelly this kit was not a NOS but a (far east?) remake?

Idle is nice so far,
Any ideas?

Thx.

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Re: Mutt quitted working

Postby rickf » October 23rd, 2017, 6:52 pm

The filter you describe is the filter I am talking about so we are on the same page there. :mrgreen: The carburetor adjustment should stall the carburetor as you turn it in before it bottoms out. The correct adjustment is to turn the idle mixture screw in until the engine starts to stumble and then turn it back out again until it starts to stumble and then turn it in o a point halfway in between those two points. This is where the idle should be best. I have found that if you experience problems with a flat spot at higher rpms at cruising speeds and light acceleration it can be cured by adjusting the carburetor a little rich at idle. This would mean setting the idle as described above and then backing the screw out until it starts to stumble and then turn it in only about one turn. Try driving it that way and see if it makes a difference.

But if you can turn that idle mixture screw all the way in and that is where it idles best then something is wrong. Someone may have turned the mixture screw in too tight at some time and enlarged the port that meters the gas for the idle mixture.
1964 M151A1
1984 M1008
1967 M416
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12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: Mutt quitted working

Postby dr. trinkmann » October 24th, 2017, 7:00 pm

Someone may have turned the mixture screw in too tight at some time and enlarged the port that meters the gas for the idle mixture.


What to do if this really happened? Not by me off course, but who knows how the carb was raped in prior. Could such damage be repaired? Maybe do a new and special screw with a lathe?

Thx
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Re: Mutt quitted working

Postby rickf » October 24th, 2017, 8:30 pm

The damage is not to the screw but to the orifice in the carb, it makes the hole larger and more abrupt. This means that the transition from the needle to the hole is much faster than it would normally be. If it does not stall the enginr even turned all the way in then there is gas getting past the needle. You can tell if this has happened by taking the carb off the manifold, back the screw out a few turns and feel inside the throat of the carb where the needle would be, if you feel the aluminum protruding at all then it has been damaged. I do not even try to rebuild these carburetors because the hole has been enlarged and there is no way to make it smaller. I consider these useless cores and they have to be replaced.
1964 M151A1
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Re: Mutt quitted working

Postby dr. trinkmann » October 25th, 2017, 3:34 am

Rick,
I even cleaned this carb a several times. Also removed burrs gently with 'scotch brite' if there were any.
Unfortunately i can't remember if there had been a protruding spot.
I can take this carb out and check for that next spring. Meanwhile I will rebuild my spare-carb with another big overhaul-kit.
But, if that seat really is widened up, how about making a complete new screw with different geometry?
There are two lathes waiting for some action in my workshop :mrgreen:

Another essential question:
Belongs that so called 'Idle mixture screw' only to idle mixture or does it affect mixture at cruising speeds as well?

Thx and greets
Dr. Trinkmann
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Re: Mutt quitted working

Postby Horst » October 25th, 2017, 6:12 am

the idle mixture does not only affect the idle but influences well into light load/partial throttle.
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Re: Mutt quitted working

Postby rickf » October 25th, 2017, 9:16 am

As Horst said, That is why if you adjust it to the rich side on idle it will eliminate the flat spot a lot of the time. As far as machining a new needle? That I can' tell you, only trial and error will tell. The problem would be that the needle is designed to move a certain amount in the hole and expose a calibrated amount of fuel at that setting. When the hole is enlarged the needle has to go further into the hole to get to the correct calibration BUT, when moving the needle it change much faster then designed since the hole to needle taper is now different. Kid of hard to explain in a way that translates so I hope you understand what I am saying.
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1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: Mutt quitted working

Postby dr. trinkmann » October 25th, 2017, 5:46 pm

so I hope you understand what I am saying

I think I understand completely.

the idle mixture does not only affect the idle but influences well into light load/partial throttle.

I asked for that, because: in case this carb has a damage with the seat of that mixture screw and can't be adjusted anymore in the recommended way, but nevertheless it can be set up to a smooth idle...should I fear damage to the engine maybe by too lean mixture? Could this carb stay in service?

A look in the exhaust outlet pipe reveals: black deposit -> not lean but rich mixture. Should be no danger for the engine but for my wallet because higher fuel consumption, right? :roll:
Should I be aware for the swirl in the gas tank not to be soaked in? :shock:
In Germany noone will check the exhaust pipe emissions (%CO) if the vehicle has a 'birthdate' of '68 in the documents and it has that 'H' for 'History Car' on the licence plate :lol:
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Re: Mutt quitted working

Postby rickf » October 25th, 2017, 6:17 pm

The exhaust pipe will always look black compared to todays cars, vehicles with carburetors will never run as clean as a computer controlled fuel injected car so the black pipe is not a worry. As long as you do not see black smoke or smell a rich mixture you are fine there. As far as running lean enough to damage the engine, if it is idling good then it will have enough gas to run without damage to the engine. You can always do what a lot of other M-151 drivers do and that is pull the choke out just a hair if it makes it run better. The hole being enlarged should actually have the affect of making it run richer more than leaner.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: Mutt quitted working

Postby rickf » October 25th, 2017, 6:22 pm

I am not totally convinced that the carburetor is damaged from your decsriptions of what is going on. I am not exactly sure what is happening but it sounds to me like an internal leak in the gasket between a vacuum port and the main fuel emulsion area. I wish I were there or you here so I could see the carb. ( I would much rather be there!) Try your other carb and make sure it is not an engine related problem since you do have the spare carb and then we can take it from there.
1964 M151A1
1984 M1008
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12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: Mutt quitted working

Postby svramselaar » October 26th, 2017, 1:49 am

hi

i read you have point ignition
if your condenser is not good it can give problems like carburetor problems
at my work i had this several times 2 til 4 times cleaning the carburetor engine will not response enough
with a new condenser all OK


george
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