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Herzlich willkommen auf der Unimog-Community-Website. Seit 1999 treffen sich hier die Mercedes-Benz Unimog- und MBtrac-Enthusiasten zum Meinungsaustausch und Fachsimpeln.

Spezial-Forum zur Unimog-Baureihe U 404 S.

Moderatoren: stephan, krahola

#574990
Hello Andrey,

The red path on your picture from the starter (58) to the generator relay (68) and than parallel to the keyswitch (56), the light switch (49) and fuse block (50) is the so called "Klemme 30" unswitched battery plus.
The red path from the keyswitch (56) to the ignition coil (28) and parallel also to the fuse block (50) is the so called "Klemme 15" switched battery plus. Note the ignition path to the coil is always unfused.
The green path from the key switch (56) via the battery lamp (55) to the generator regulator (69) is the generator exciter and signalling line.
#574991
Hello Jurgen,

I measure voltage drop at the point '+' is coming from starter at cut off relay, so even before going thru ignition switch...so this cable or connection should be bad. I'm relay tempted to put direkt line from Accumulator thru new ignition relay to coil.

Andrey
Zuletzt geändert von Andrey Nikolov am 09.04.2024, 16:18, insgesamt 2-mal geändert.
#574994
Hello Andrey,

why you want to use a ignition relay. Relay are used if either the switch cannot support the load current or if the high current cables can be shorten insted of routing through the switch.
Both are not valid for the 404 as the main keyswitch can support the full load and the coil is right beside the switch.
#574999
Hello All,


I start the engine tonight with 2 batteries, even then, engine starts just when you release start button and engine still rotate by inertia (thanks to 7 to 1 compression :D :D :D ) . Yep the batteries are small, just 44ah that I bought brand new thinking that will be enough for 24V system, but now maybe one 44Ah is way too small.

any way it seems that transistor ignition module that I bought, don't works at 7-8 Volts...should think something else.

Overall expression for half an hour back and front in front of my garage:

- gas leak at front seal of down pipe...is there new seals on market or some upgrade??
- oil leak from rear seal...that will be fun...I bought new rope and collect power to this job...some advice/PN for oil filter? I bought some thru parts site, but is way to big????
- clutch bearing is grinding something :D :D :D :D , but some time not.
- generally gears are shifting
-brakes works
- I forgot to close lid under air filter and the front tire grab it and bend it a little :D :D :D
- any solution to convert oil bath filter to dry element???

Andrey
Zuletzt geändert von Andrey Nikolov am 09.04.2024, 16:17, insgesamt 2-mal geändert.
#575004
Hello Andrey

You said that you measured this voltage drop to around 8V at the generator relay (68)
You measured this drop all the time or only if you press the starter knob?
As you changed your system voltage from 24 to 12 V you can't use the old generator (70), generator relay (68) and genarator regulator (69)
Did you also measured the voltage drop during starting
1. direct at the battery?
2. direct at the starter?
As you have changed the starter from 24V to 12V and the new starter has the same power as before than the current from battery is doubled as before. So on all old lines the voltage drop is also doubled. For this a 44 AH Battery is really to small.
To make it correct you have to change all main wiring to a bigger size to minimize the lost.

Which seal on "down pipe" you mean (photo or article no.)
#575005
Hello Jurgen,

You said that you measured this voltage drop to around 8V at the generator relay (68)
You measured this drop all the time or only if you press the starter knob?

yes..when starter is activated

As you changed your system voltage from 24 to 12 V you can't use the old generator (70), generator relay (68) and generator regulator (69)

Those parts are out of the Vehicle

Did you also measured the voltage drop during starting
1. direct at the battery?

10.5V

2. direct at the starter?

didn't check there

As you have changed the starter from 24V to 12V and the new starter has the same power as before than the current from battery is doubled as before. So on all old lines the voltage drop is also doubled. For this a 44 AH Battery is really to small. To make it correct you have to change all main wiring to a bigger size to minimize the lost.

New line from '+' distributor klemme (this bolted on middle of chassis) 100mm2 whit new cable shoes (pressed and soldered). Generally the original '+' lines at least 200mm2 , so very solid. Should be enough.

I'll inspect engine ground...actually where is this to look?




Which seal on "down pipe" you mean (photo or article no.)

Bild

Andrey
Zuletzt geändert von Andrey Nikolov am 09.04.2024, 16:17, insgesamt 2-mal geändert.
#575006
Hello All,

Yep...for limited time (before scrap them) I'll have:

-compressor, air pressure regulator, air defroster, air brake cylinder, pressure vessel, trailer air brakes regulator and other small bits....compressor works..;other bits...don't know.

- generator with cable, regulator, cut off relay, wind washer pump and bottle, fire signals/horn electrical box, electrical fuel pump

Andrey
Zuletzt geändert von Andrey Nikolov am 09.04.2024, 16:17, insgesamt 2-mal geändert.
#575007
Hello Andrey

please offer your obsolete parts here on "Biete" Forum biete-f32.html
Best make a photo of each part, give a price indication for each part and give contact details.
I think some parts you can sell.

The exhaust seal you can get for example from VK SARS BVBA (Belgium)
https://www.google.de/url?sa=t&source=w ... 4coHrZYVyv

Regarding electric
First you see battery is going down to 10,5 due to the high starter current. Better and/or bigger battery has less drop
Second as you not measured directly on the starter I think the main droß you have between battery and starter on plus side. And between battery, main switch (61) and ground.
I don't believe that you have 100mm² or 200mm² cables. !00mm² means 1.1cm diameter of the cooper line.
The standard cable main caable from battery to starter and from battery to main switch is 50mm².
The engine grounding is going via the engine and gearbox mounts.
#575014
Hallo Andrey
Please note our rules, every post starts with a nice greeting and ends with the signature of your name
H(Mod)
#575040
Hello All,

I put a line direct from battery thru relay and fuse and signal from ignition switch in order to power ign. coil. Truck starts easier, but still somewhere is massive voltage drop.

Good news is that there is back light switch on F/R lever and now I have working back light. I still should find brake light line and horn and I\m ready with the lights.

Andrey
#575044
Hello Andrey,

if you have the normal 404.1 main brake cylinder the switch for the brake light is at the back end of this cylinder.
Again give information about your voltage drop.
When you measured what voltage drop at which measurement point.
During starting of the motor a (small) voltage drop is normal but not massive
During engine running no voltage drop has to be mesured at your fuse.
Did you use still the resistor in front of your ignition coil at the ignition line?
#575045
Hello Jurgen,

When you measured what voltage drop at which measurement point.
unimog 1151.jpg
unimog 1151.jpg (332.68 KiB) 2462 mal betrachtet
Practically at the starter , so no switches between.

During starting of the motor a (small) voltage drop is normal but not massive
During engine running no voltage drop has to be mesured at your fuse.

Did you use still the resistor in front of your ignition coil at the ignition line?

No. I remove it. According to transistor ignition module instruction - is no needed. But retrospective (now I'm thinking) problem was preexisting. The Slovenian grandpa (from whom I bought the truck), bypassed the resistor too and coil was connected directly to some '+' with power next to ign key (Klemme 15)

Andrey
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