M151 TECH TIPS
Here are a number of tech tips for the M151
series of 1/4 ton Multi Utility Tactical Trucks
series of 1/4 ton Multi Utility Tactical Trucks
These tech tips are taken directly from posts to the MuttMotorpool club/group
over the last two years. The members of this group have hundreds of years of
combinred experience with Mutts and when there is a question someone
almost always seem to have an answer.
IF YOU HAVE ANY GREAT TECH TIPS FOR MUTTS PLEASE EMAIL
THEM TO ME
over the last two years. The members of this group have hundreds of years of
combinred experience with Mutts and when there is a question someone
almost always seem to have an answer.
IF YOU HAVE ANY GREAT TECH TIPS FOR MUTTS PLEASE EMAIL
THEM TO ME
The Good old Carb problems!
From: ricksbro
Date: Wed Jan 24, 2001 9:19 am
Subject: Re: Zenith Carb Rebuild
Please accept this as constructive and not
critical. Not to be to simplistic but, have we all
forgotten the basics? The 151 engine is 1 step up from a
Model A (with a fording valve)in operation. The engine
needs fuel in the correct mixture & spark at the right
time to operate correctly. This can be verified with
simple tools in simple order without randomly replacing
parts.<br>1. Verify fuel flow & pressure at carb inlet.<br>2.
Verify ign. timing.<br>Any poor run condition that is
corrected by the application of the choke usually indicates
a lean fuel mixture. While this can be caused by
improper float setting and carb adjustment it is most
likely a vacuum leak downstream from the carb,
especially if it is intermittent. You can track this down
with the application of propane (stick a hose over the
end of a propane torch...UNLIT) and probe
joints/gasket surfaces while engine is running (FIRE
HAZZARD)Don't forget to man handle the carb/manifold etc. while
doing this. If the engine speed increases while doing
this you have found the leak. <br>I know we like to do
everything for maintenance but if you can come up with the
correct ignition adapters from a LVCT kit it may be worth
a trip to an old service station that has a
"antique" engine analyser to check the ignition secondary.
In less than 1/2 hour they can verify correct
operation of the distributor (cam, advance, point dwell,
coil output), wires, plugs, timing and fuel mixture,
compression balance etc. Happy hunting.
Date: Wed Jan 24, 2001 9:19 am
Subject: Re: Zenith Carb Rebuild
Please accept this as constructive and not
critical. Not to be to simplistic but, have we all
forgotten the basics? The 151 engine is 1 step up from a
Model A (with a fording valve)in operation. The engine
needs fuel in the correct mixture & spark at the right
time to operate correctly. This can be verified with
simple tools in simple order without randomly replacing
parts.<br>1. Verify fuel flow & pressure at carb inlet.<br>2.
Verify ign. timing.<br>Any poor run condition that is
corrected by the application of the choke usually indicates
a lean fuel mixture. While this can be caused by
improper float setting and carb adjustment it is most
likely a vacuum leak downstream from the carb,
especially if it is intermittent. You can track this down
with the application of propane (stick a hose over the
end of a propane torch...UNLIT) and probe
joints/gasket surfaces while engine is running (FIRE
HAZZARD)Don't forget to man handle the carb/manifold etc. while
doing this. If the engine speed increases while doing
this you have found the leak. <br>I know we like to do
everything for maintenance but if you can come up with the
correct ignition adapters from a LVCT kit it may be worth
a trip to an old service station that has a
"antique" engine analyser to check the ignition secondary.
In less than 1/2 hour they can verify correct
operation of the distributor (cam, advance, point dwell,
coil output), wires, plugs, timing and fuel mixture,
compression balance etc. Happy hunting.
From: j_w_whitten3
Date: Tue Jun 13, 2000 6:42 pm
Subject: Re: Zenith Carb tuning tip
Otter-<br>My National Guard buddy who runs one of
the nearby maintenance shops told me that they were
told to set the chokes on MUTT carbs a little off of
"all the way in". His procedure was to set it
normally, then slowly pull it out until it ran the best,
then to hold the butterfly lever, loosen the screw,
and push the knob all the way in and retighten the
screw. That way "all the way in" actually ran "a little
choke" all of the time. In other words, he was taught to
do exactly what you just found out works the best!
When he gets back from summer camp I'll see what other
tips he has.<br>Glad to hear it's running
right!<br>John
Date: Tue Jun 13, 2000 6:42 pm
Subject: Re: Zenith Carb tuning tip
Otter-<br>My National Guard buddy who runs one of
the nearby maintenance shops told me that they were
told to set the chokes on MUTT carbs a little off of
"all the way in". His procedure was to set it
normally, then slowly pull it out until it ran the best,
then to hold the butterfly lever, loosen the screw,
and push the knob all the way in and retighten the
screw. That way "all the way in" actually ran "a little
choke" all of the time. In other words, he was taught to
do exactly what you just found out works the best!
When he gets back from summer camp I'll see what other
tips he has.<br>Glad to hear it's running
right!<br>John
From: gbpmi
Date: Thu Apr 19, 2001 6:11 am
Subject: Mutt carb waffle
Hi People,<br><br>The National Guard mech was
right. They are supposed to be set up with play in the
choke cable. I forget which manual mentions it but one
certainly does. Maybe it was in PS magazine.<br><br>To set
up your float height, make it no more that 3/8"
max.<br><br>Squirting oil on your carb? Wow!<br>Gav.
Date: Thu Apr 19, 2001 6:11 am
Subject: Mutt carb waffle
Hi People,<br><br>The National Guard mech was
right. They are supposed to be set up with play in the
choke cable. I forget which manual mentions it but one
certainly does. Maybe it was in PS magazine.<br><br>To set
up your float height, make it no more that 3/8"
max.<br><br>Squirting oil on your carb? Wow!<br>Gav.
From: cole66413
Date: Tue Apr 17, 2001 9:20 pm
Subject: Re: to much gas
If you have the Zenith carbureator, make sure the
stand tube is in place. If someone has removed the
float bowl, it is easily lost. Also, you say you
checked the needle and float, how about the float height?
If it is too high, it will cause your problem.
Date: Tue Apr 17, 2001 9:20 pm
Subject: Re: to much gas
If you have the Zenith carbureator, make sure the
stand tube is in place. If someone has removed the
float bowl, it is easily lost. Also, you say you
checked the needle and float, how about the float height?
If it is too high, it will cause your problem.
OTHER TECH TIPS
Angelo sent me this tip in an email and asked me
to share it with Ya'll,<br> Thanks Angelo,<br>
otter<br><br>. The rear diff whine all the time <br>even full of
good oil (which I suggest to be a 140 more than
anything else) <br>is sign of age and poor maintenance
from the prev. owner or a long period of <br>time
sitting and waiting to be demilled or sold after a deep
water bath that <br>mix up in the diff box. That create
rust and deposit between the teeths and <br>/or the
bearings. If the growl is bother you the only solution is
to find a <br>brand new (in the box with the foam)
unit and put it on. It will take a few <br>hours on
the ramps or a lot less on a lift, but the result is
often poor: the <br>tolerances in the mutt's mechanics
are very loose to allow repairs to be <br>performed
in combat situations where there is no presses,
lathes and torqe <br>wrenches, so you'll find soon that
something else is noisy if not the new <br>(expensive)
differential itself! A way to quiet down the singers (like we
<br>call them in Italy) is to put havy rubber washers
between the diff body and <br>the mounts on the under
chassis. I often use an old tire from a heavy truck
<br>(tractor trailers or construction vehicle), cut out
rectangular pieces the <br>size of the touching surface of
the differential box, punch out a hole of a <br>tight
size so the bolt will keep in while wrenching and the
result is less <br>vibration transmission to the body of
the mutt and a much quiet ride. Don't <br>use too
thick rubber otherwise you'll change the angle of the
tranny shafts, <br>but get enough rubber to insulate the
singer! Another way is to buy a very <br>old unit for a
few bucks, open it up and start to play with the
adjustment <br>inside so that a blue dye (you can find it by
any good auto repair shop) put <br>on some of the
pinion teeth will cover a good part of the ring tooth's
<br>surface signaling a perfect or near perfect contact
between them. I've seen <br>people adjusting a mutt diff
by putting a flat screw driver between the teehs
<br>and "feel" the play, but I strongly discurage that!
Just play with the old <br>diff for a while and when
you feel ready, pull the good out and reallign it.
<br>Use new gasket and seals kit when you close it and it
will be all right. <br>Please pubblish this tricks on
the board for me, I still have to find the drawing of
the <br>trick to keep the A1 from rolling
over.<br><br>Angelo
to share it with Ya'll,<br> Thanks Angelo,<br>
otter<br><br>. The rear diff whine all the time <br>even full of
good oil (which I suggest to be a 140 more than
anything else) <br>is sign of age and poor maintenance
from the prev. owner or a long period of <br>time
sitting and waiting to be demilled or sold after a deep
water bath that <br>mix up in the diff box. That create
rust and deposit between the teeths and <br>/or the
bearings. If the growl is bother you the only solution is
to find a <br>brand new (in the box with the foam)
unit and put it on. It will take a few <br>hours on
the ramps or a lot less on a lift, but the result is
often poor: the <br>tolerances in the mutt's mechanics
are very loose to allow repairs to be <br>performed
in combat situations where there is no presses,
lathes and torqe <br>wrenches, so you'll find soon that
something else is noisy if not the new <br>(expensive)
differential itself! A way to quiet down the singers (like we
<br>call them in Italy) is to put havy rubber washers
between the diff body and <br>the mounts on the under
chassis. I often use an old tire from a heavy truck
<br>(tractor trailers or construction vehicle), cut out
rectangular pieces the <br>size of the touching surface of
the differential box, punch out a hole of a <br>tight
size so the bolt will keep in while wrenching and the
result is less <br>vibration transmission to the body of
the mutt and a much quiet ride. Don't <br>use too
thick rubber otherwise you'll change the angle of the
tranny shafts, <br>but get enough rubber to insulate the
singer! Another way is to buy a very <br>old unit for a
few bucks, open it up and start to play with the
adjustment <br>inside so that a blue dye (you can find it by
any good auto repair shop) put <br>on some of the
pinion teeth will cover a good part of the ring tooth's
<br>surface signaling a perfect or near perfect contact
between them. I've seen <br>people adjusting a mutt diff
by putting a flat screw driver between the teehs
<br>and "feel" the play, but I strongly discurage that!
Just play with the old <br>diff for a while and when
you feel ready, pull the good out and reallign it.
<br>Use new gasket and seals kit when you close it and it
will be all right. <br>Please pubblish this tricks on
the board for me, I still have to find the drawing of
the <br>trick to keep the A1 from rolling
over.<br><br>Angelo
Ped-<br>You need to plan on pulling the entire
assembly, as the engine, tranny & transfer,starter,
generator or alternator, and radiator all come out as one
unit. The easiest way is as follows:<br>Pull 3 bolts
from each side of the grille, disconnect all wires
(they plug in) and remove grille. Disconnect and remove
air cleaner (the mounts can stay). Disconnect + side
of battery. Remove tranny cover plate (between & in
front of seats) and tranny shift lever and transfer
lever, and loosen the park brake so it can be moved out
of the way. Disconnect front & rear drive shafts
from transfer. Disconnect all air, water, fuel,
vacuum,and electrical lines from the engine, generator(or
alternator) and tranny assy. (Don't forget the ground and
starter cables and the choke and accelerator
connections). When everything is loose, connect a chain between
the lift points at each end of the engine and remove
the 2 engine mount bolts and the 2 transmission mount
bolts. The whole thing comes out through the front of
the MUTT. Removal and replacement should take about 2
to 4 hours if you don't run into any problems. By
the way, if you have a heater, cut off the valves at
the water pump and elevate the hoses as soon as you
pull them loose-tie them up so you don't lose your
coolant.<br> Good Luck!<br>John
assembly, as the engine, tranny & transfer,starter,
generator or alternator, and radiator all come out as one
unit. The easiest way is as follows:<br>Pull 3 bolts
from each side of the grille, disconnect all wires
(they plug in) and remove grille. Disconnect and remove
air cleaner (the mounts can stay). Disconnect + side
of battery. Remove tranny cover plate (between & in
front of seats) and tranny shift lever and transfer
lever, and loosen the park brake so it can be moved out
of the way. Disconnect front & rear drive shafts
from transfer. Disconnect all air, water, fuel,
vacuum,and electrical lines from the engine, generator(or
alternator) and tranny assy. (Don't forget the ground and
starter cables and the choke and accelerator
connections). When everything is loose, connect a chain between
the lift points at each end of the engine and remove
the 2 engine mount bolts and the 2 transmission mount
bolts. The whole thing comes out through the front of
the MUTT. Removal and replacement should take about 2
to 4 hours if you don't run into any problems. By
the way, if you have a heater, cut off the valves at
the water pump and elevate the hoses as soon as you
pull them loose-tie them up so you don't lose your
coolant.<br> Good Luck!<br>John
From: gbpmi
Date: Wed Dec 19, 2001 9:29 pm
Subject: Re: Carby Modification
Gentlemen,<br>You have not adjusted your choke
cable correctly. It's as simple as that. If you check
in the -20, you will find that 1/8' adjustment is
supposed to be pre-set. <br><br>If you do not adjust the
cable as such, you will find that you need to pull just
a wee bit of choke to get her to idle
nicely.<br><br>RTFM as we say where I come from.
:-)<br><br>Cheers<br>Gavin
Date: Wed Dec 19, 2001 9:29 pm
Subject: Re: Carby Modification
Gentlemen,<br>You have not adjusted your choke
cable correctly. It's as simple as that. If you check
in the -20, you will find that 1/8' adjustment is
supposed to be pre-set. <br><br>If you do not adjust the
cable as such, you will find that you need to pull just
a wee bit of choke to get her to idle
nicely.<br><br>RTFM as we say where I come from.
:-)<br><br>Cheers<br>Gavin
From: arhhhbuckooo
Date: Tue Jun 13, 2000 12:40 pm
Subject: Zenith carb tuning tip
I swaped a rebuilt zenith carb for my old one
today on my 72 M151A2.When I was tuning up and test
driving,First I set the choke butterfly to as far open as it
would go with the cable pushed all the way in.I found
that I had some hesitation when accellerating.I pulled
the choke cable out just little and it ran
perfect.When I looked at the butterfly I found that if it is
tipped up a couple of degrees from full open it's
centered in the venturi making the smoothest air flow into
the carb.I reset the cable so full open has the
butterfly centered in the venturi and now it it
accellerates like a bat out of hell, smooth and strong.Well
ya'll thats all I have fiqured out for today but the
MUTT really goes now ---I'm gonna go find some mud to
play in--------otter
Date: Tue Jun 13, 2000 12:40 pm
Subject: Zenith carb tuning tip
I swaped a rebuilt zenith carb for my old one
today on my 72 M151A2.When I was tuning up and test
driving,First I set the choke butterfly to as far open as it
would go with the cable pushed all the way in.I found
that I had some hesitation when accellerating.I pulled
the choke cable out just little and it ran
perfect.When I looked at the butterfly I found that if it is
tipped up a couple of degrees from full open it's
centered in the venturi making the smoothest air flow into
the carb.I reset the cable so full open has the
butterfly centered in the venturi and now it it
accellerates like a bat out of hell, smooth and strong.Well
ya'll thats all I have fiqured out for today but the
MUTT really goes now ---I'm gonna go find some mud to
play in--------otter
From: j_w_whitten3
Date: Tue Jun 13, 2000 4:36pm
Subject: Re: REMOVING ENGINE
AND TRAN.
Date: Tue Jun 13, 2000 4:36pm
Subject: Re: REMOVING ENGINE
AND TRAN.