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Discussion Starter #1
Well I think I may have the tranny issue resolved, or at least it's much improved. Slight modification of shift plate, a little alignment change upon installation of same and new synth. fluid has gotten me reverse just about all the time. More driving may improve it...hope so.
New issues, charge light is on and irradic tach (read: frequently not working). I had the same issue on my Caterpillar backhoe (Bosch alternator), anybody know if the tach signal comes from the alternator?
If the rig sits for a couple days, it starts right up but then dies in a minuite or so, no fuel. Pumping the primer brings it back and then it runs fine...failing transfer pump? Where is the rascal located? (Gotta get those manuals!)
Finally, here is a link to some pics:
1979 Case Unimog
Turns out it is a Lake Placid unit, too bad they painted it!
Thanks for the help, Doug
 

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Your electrical problem is corrosion on the fuse ends where they sit in the fuse holders. Go in there, use your fingers to lightly squeeze the fuse holder into compression and spin each fuse around a few times. Then, when you're ready, replace the fuse blocks and those stinking Lucas invention open fuses with modern stuff.

Your fueling problem is either a fuel pump diaphragm (no aux lift pump in a 406 - it's all the engine mounted mechanical pump), a mis-seated or clogged fuel filter (probably the small one right after the tank, if Case Mogs have those), a leaky hose or the primer pump itself leaking. Unfortunately, it's probably remove-and-replace time for you until you find the culprit.
 

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Your electrical problem is corrosion on the fuse ends where they sit in the fuse holders. Go in there, use your fingers to lightly squeeze the fuse holder into compression and spin each fuse around a few times. Then, when you're ready, replace the fuse blocks and those stinking Lucas invention open fuses with modern stuff.

That is my guess as well.

Your fueling problem is either a fuel pump diaphragm (no aux lift pump in a 406 - it's all the engine mounted mechanical pump), a mis-seated or clogged fuel filter (probably the small one right after the tank, if Case Mogs have those), a leaky hose or the primer pump itself leaking. Unfortunately, it's probably remove-and-replace time for you until you find the culprit.
Keith, the assembly that the primer threads into is a low pressure mechanical lift pump. It is bolted to the block with three 13mm nuts. Inside there are 2 plastic plungers that seal against a machined spot on the housing. Mine were not sealing well and would cause me to loose fuel prime overnight. Also, if you have the old style primer that has to be screwed down it can leak even when you think it's screwed down tightly. Replace it with the new style, any diesel mercedes car pump is the same. Lastly, the origional plastic fuel lines can leak where they are pressed onto the brass banjo fittings. If you can spin the banjo in the line it is probably leaking. Hope that this is of some help.
 

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Reddog, how familure with diesel engines are you? Particularly in the area of what air leaks in fuel lines can do to a diesel engines performance.
 

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Discussion Starter #5
Thanks for the info. So am I hearing that if the primer pump is not tightly screwed dow, this can be the problem? Originally the banjo fitting at the back of the head was leaking, but that has been resolved. No other leaks apparent. I'll screw down the pump and check the filter assy. for air leaks.
Also, the alternator circut goes through a fuse? I suppose this has to be the enegizing feed. Any hints on which fuse? I've struggled with this type fuse since my first foray into German electrics in '76 with a Karma Ghia, I'll do the emery cloth and dielectric grease routine and go from there.
Thanks, Doug
 

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Coachgeo, I'm pretty familar with these issues, familiar enough to know they are problematic and can be troublesome to hunt down. I'm a mechanic by trade and own and operate a tire store/gas station here in Gunnison. I've got a few other diesel powered vehicles other than the Mog, I was just looking for likely culprits. Doug
 

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Here is the pump and new style primer. One valve is under the primer, the other under the cap to the primers left. Under the big front nut is a spring-diaphram assembly. Also, if your truck has the glass sediment bowl, check the condition of the oring that seals it, and make sure the screen doesn't look like mine.
 

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BenzWorld UNIMOG statesman
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Coachgeo, I'm pretty familar with these issues...
ok good. Didnt want to assume.

You probably know this then but for others who may not, on banjo bolts and other fittings where copper crush washers are used..... from what I've read and experienced a little they can "look good" and gets reused thinking all is fine. Have discovered this is not a good idea unless you re-anneal (sp?) them.

They are as they say "crush" washsers and they do... compress on crush. Thusly they often won't reseal on the second use. PITA thing is when you get a "new to you" used rig you have no way of knowing if one or more of them did get reused by the PO and if this is causing the leak or something else.

They are pretty cheap if you can find them in the right size. Otherwise just re-anneal them with a torch.
 

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Also, the alternator circut goes through a fuse? I suppose this has to be the enegizing feed. Any hints on which fuse? I've struggled with this type fuse since my first foray into German electrics in '76 with a Karma Ghia, I'll do the emery cloth and dielectric grease routine and go from there.
Thanks, Doug
If you owned a Karmann Ghia, you know the drill - do all the 'things' - the Mog system will have the same quirks. Yeah, the alternator field circuit is fused - don't know which one - my service manual is out in the shop.

I'll let somebody else work the fuel issue with you - I've had few problems with mine, so I don't have experience like I do with the electrics ;)
 

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Tach wire comes from the alternator to the tach, I think from memory it is the White/Blue wire coming from the back of the alt. If you do replace the alt, make sure the pulleys are the same so your tach remains accurate. You can pull the alternator very easily, split it in half and check the brushes and diodes very easily. If you get that far come back and I, or someone else should be able to elaborate. Very easy, though. And everyone, if your alternator light is not coming on when the engine is not running and the key is in the run position, you are probably not charging. The bulb must be in the circuit. You may just have a bad wire to the tach, and a loose wire, the big red one from the starter to the alternator, no fuse. My MB494 had a bad wire to the tach, Be careful when tightning the wire for the tach onto the alternator. If you move the stud, even a little you can break off the small wire inside the alternator from the stud to the windings. The you must open up the alternator and, very carefully solder it back together. If your tachs wire is all perfect with a good ground at the tach, then that internal alternator jumper could be your problem. Also, when and if you pop open the alternator, check and grease the bearings in it.
 

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Discussion Starter #12
All good info. I went down to the shop (more snow here...when will it end!) and fiddled. Fixed a few wiring issues and finally pulled the alternator, I'll take it down and have it checked tomorrow. The tach signal is intermittent, and like I said earlier, I had this same issue with my backhoe, so I've been down this road before. If it check out to be bad, it'll go to the same shop that fixed the hoe alternator.
I'll watch the fuel leak down over the next few days and see where that leads, I suspect the primer pump/transfer assy, but we'll see.
I can't get power to my windshields. I have power at the switches, and the switches energize the relays, but no power to the windshiels connections. It seems like I don't have a high amperage feed to the relays and all fuses are good...any idea where the high power feed comes from? There are 2 small relays, 1 larger one and another really larger one (closest to the firewall), the really large one almost looks like a voltage regulator. The cover on it was already loose and something inside (resistor?) looks fried, but I checked all the connections and there is not a high amp feed to the thing...???
Thanks again for the help and send some sunshine my way. Of course, there will be lots of mud to play in this spring, so there is a bright side to everything. Doug
 

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I was thinking about this last night and realized that I overlooked the most obvious, simple thing. Unbolt your fuel pickup tube and check the screen sock on the end of it. If your truck sat for a while, stuff can grow in the tank and clog it quickly. A friends truck did the exact same thing till he drained and cleaned the tank. HTH
 

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Doug, I agree with Seth, the shut down after start usually means that the fuel line up to the final filter is draining because you have a leak in the line or gaskets starting with the filter bowls and going all the way down to the tank and the fittings in the tank above the fuel level. If air can enter it will allow the fuel to drain and you quit when the air `bubble' hits the main pump.
I had similar tach and dash light problems until I replaced the Prince of Darkness fuse blocks with new spade style fuses.
Dave
 

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Discussion Starter #17
Thanks Dave. I plan to check the air leak issue when I get the alternator back form the shop, I have to rebuild the clutch MC as well, so I'm planning on killing a few birds at one time. Doug
 

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Discussion Starter #18
Update:
The alternator returned from the shop yesterday, $135.00, bearings, brushes, diode. Installed it and problem solved, no charging light and tach works like a champ. When I pulled the alternator, I made sure the fuel primer was fully and tightly screwed down. It sat for about a week and fired right up, no more dieing issue. 2 problems down...we don't want to talk about what is still on the list. Thanks for all the input and advice. Doug
 
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