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Unimog_404.113_1970
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178 Posts
Discussion Starter #1
As a new user, (and a new Unimog owner) i´d thought i´d
present myself to the people using this board!

It does´nt seem like there´s so many of you, but here in
Sweden there is NOONE to talk mog to.

I´m a 25 year old guy who just bought my first mog, but
i have been wanting one for over ten years, and searching
for one for more than a year. The perfect example came
up, and i bought it. Unfortunatly it does´nt run very
vell, but i hope that a "civilian ignition" a fuel pump repair kit, and some other stuff vill fix that!

I live in Sweden and there are not so many Unimog´s
around here, the most offroading is done with smaller
veichles like Jeep´s ...

Here are some pics of my mog.





My Unimog is an 404.1 built in 1970. It has only 25000 km on it, and has served as a firetruck til 1995. It has an orginal winch type A mounted in front.
 

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Unimog_404.113_1970
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178 Posts
Discussion Starter #3
Thanks!

Unfortunatly it does´nt run very well (hardly at all), for the moment,
but i´m hoping the new parts will fix that.
I have ordered parts from http://expeditionimports.zoovy.com/ does anyone have any experience with them?

The engine will only run with full choke. It stars very easy, even when -15 degrees Celsius. When the engine is warmer and i push in the choke, the engine idles very nice for 10-12 seconds, and then dies. It does´nt respond to the throttle att all, just backfires if i try.

If anyone has any ideas feel welcome to post here!
 

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Unimog_404.113_1970
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178 Posts
Discussion Starter #5
Crashmaster - 3/4/2005 5:27 PM

Is there throttle response while the choke is still on?
yes, when the engine is cold, not perfect, but it revs ...
 

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Unimog_404.113_1970
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178 Posts
Discussion Starter #6
today i removed both carbs!

the journey from this;

to this;

was not easy, but i made it! ...[:D]

the tiny o-rings fitted aorund one nozzle i could
remove without tearing the carb apart just falled
to pieces when i removed the nozzle, so the cars need
a rebuild alright!

i´m thankful for all tips regarding the rebuilding process! (have rebuilt carbs before, but no Zenith 32 NDIX)
 

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'76 406.145 Doka tug
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290 Posts
It sounds like a fuel delivery problem all right. Since it revs up under choke I'ld assume fuel delivery volume to carbs is ok, at least sufficient to idle off-choke. Idleing well at times would eliminate low manifold vacuum. I would suspect restricted main jets, possibly due to sediment accumulation, as stuck floats would be uncommon on two carbs at once.

So, not enough venturi vacuum to draw enough fuel from the float bowls normally. Relies on choke to forcibly suck fuel in then idles off-choke on the fuel pooled in the intake untill it dies. Backfiring on accel due to lean misfire.

Cleaning the carbs is definatly a good first step. Take lots of pictures and measurments (float level) and be sure to find all the set-up specifications for those carbs. I have no technical info for you unfortunatly,... diesel - ftw :) good luck
 

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Unimog_404.113_1970
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Discussion Starter #9
thanks for the ideas!

i have taken the first carb apart, and it was surpisingly clean inside. i will remove all
nozzles and blow them clean with compressed air.

the o-rings are probably standard stuff, i´ll find new ones, but there is no chanche that i´ll find new gaskets on such short notice, does anyone have experience using gasket on a tube (blueish, silicone-like stuff)??
 

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404.s x VW-Lt
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189 Posts
i bring my (chainsaw)carbs to a workshop which have a ultrasonic cleaner. with such a cleaner it looks like new and all dirt in difficult places comes off.
 

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Unimog_404.113_1970
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Discussion Starter #11
today i cleaned the inner workings of my first Zentih carb. [:p]

my friends at work looked funny at me and wondered if i´d ever get the carb to work again ... [:D]

i attach som pictures of the "center part" of the carb,
if someone is interested ...

i will assemble the carb with blue silicone "floting" gasket, and see if the engine works better.
no money for a rebuild now, but will do that later on.
 

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Unimog_404.113_1970
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Discussion Starter #12
finished with the first carb! [^]

(does anyone know how many turns the adjustment screws at the bottom of the carb should be screwed out, to start with? they were 1,1/4 turns out.)
 

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mogless, except for my friends MB4-94. And a bunch of other diesel junk.
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2,512 Posts
The tube gasket stuff is less than ideal for carbs, as it is so squishy it tends to squeeze out and block places you never intended. Don't ask how I know this. If you must... use the stuff sparingly. Also, when assembling two pieces, first seat the pieces together, and get the screws started but dont tighten them yet. Wait a few hours so the goop gets a chance to gel, now when you tighten the screws it will compress for a good seal instead of squeezing out beads to get sucked into the accelerator pump and other places. Again, don't ask how I know. And yes, 1 to 2 turns should get you started, but dual carbs will take a bit of tinkering to sync correctly. Make sure that your linkage is adjusted so that both carbs throttle plates are completely closed at the same time, and that they start to open at exactly the same time. Dual carbs are great when they're properly dialed, otherwise, be patient. Good luck, Seth
 

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Unimog_404.113_1970
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Discussion Starter #14
esde - 3/8/2005 2:43 PM

The tube gasket stuff is less than ideal for carbs, as it is so squishy it tends to squeeze out and block places you never intended. Don't ask how I know this. If you must... use the stuff sparingly. Also, when assembling two pieces, first seat the pieces together, and get the screws started but dont tighten them yet. Wait a few hours so the goop gets a chance to gel, now when you tighten the screws it will compress for a good seal instead of squeezing out beads to get sucked into the accelerator pump and other places. Again, don't ask how I know. And yes, 1 to 2 turns should get you started, but dual carbs will take a bit of tinkering to sync correctly. Make sure that your linkage is adjusted so that both carbs throttle plates are completely closed at the same time, and that they start to open at exactly the same time. Dual carbs are great when they're properly dialed, otherwise, be patient. Good luck, Seth
thanks for the tip! i´ve been around the tube gasket
before, and i acctually followed your directions exactly ...[:D]

i was worried about the thickness though, the std. gasket
is thicker than the tube stuff, i hope that it wont
be a problem ... i have never adjusted two carbs before,
that will be exiting!

there are no other needles to adjust, right?

i hope that the engine will work much better, i´m
anxious to try it for real! [:p]
 

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mogless, except for my friends MB4-94. And a bunch of other diesel junk.
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2,512 Posts
The srcews control the idle mixture, the position of the throttle plate controls throttle(or idle) speed. The position of one does affect the adjustment of the other, and adjusting any of it before the engine is warmed up is futile as the engine will be running off of the choke. Get it warm no matter how much it stumbles, then adjust it while it's hot. Remember to turn all screws the same # of turns untill it's running well enough to sync. Good luck, Seth
 

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Unimog_404.113_1970
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Discussion Starter #16
thanks! ...

i´m just about agetting started with putting together
the second carb! [:)]
 

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Unimog_404.113_1970
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Discussion Starter #17
btw, does anybody now how important the seal between
the carb body, and the choke lid is?

its a narrow edge, and it was tricky to get the silicone
gasket to spread evenly over the surface ...
 

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Unimog_404.113_1970
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178 Posts
Discussion Starter #18
ii have just finished putting the car back together
agian! i seems to work much better now, but it still
backfires a bit when cold .. when it got heated up
it ran almost perfectly! now i´m gone take it for
a spin, and if someone has anymore tuning tips
im greatful! ...

(have no special tool though, no lambda meter, not even a vacuum gauge ... no sync. tool ...[:I])
 

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Unimog_404.113_1970
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178 Posts
Discussion Starter #19
forget the previous post ...[V]

the enginge is no longer happy ... i just went
in, and filled the air filter with oil, screwed
it back on, and then took a drive ...

very strange idle, when i take my foot off the gas pedal
it stays high (~1000 rpm) and then it get lower and
lower, until the engine dies ...

i dont now weither its an adjustment problem, or something
else, but i noticed that one of the carbs leak a
little fuel ... no meaning with trying to adjust
that mess .. have to wait till i can afford reuild kits
for them ...
 

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Unimog_404.113_1970
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Discussion Starter #20
today i changed the ignitions system ...
no problem there ....

the engine runs smother i think, i have´nt set the timing yet ...

i did´nt change the "no idle without choke"-problem though ... same as before ...

another strange thing happend, when i started the
engine after i´d taken it for a spin .. when running on the starter, the engine turned very slow, like one revolution, then stop, one more, then stop ..
it has happend before, but only one or two relovutions,
then the enginge started spinning as normal ..

i suppose this could have something to do with the ignition beeing not timed, or?

all ideas are very welcome!
 
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