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Discussion Starter · #1 ·
I started this to keep it out of the DOKA cab lifting thread. This might be pretty boring, and if looking at rust damage and metal surgery isn't your cup of tea, then this probably won't be of any interest.

This is from the Unimog Community.de website, and the fellow has a high roof U1600 that was a communal service UNIMOG. It had rust in all of the classic places, and he goes after every square inch of it. He put in a tremendous amount of work, and it made me think of what a bargain all of those new UHN Cabs were when they appeared on dealers lots. They were take-offs because MB would not sell just the chassis to the DINGO makers at the time, so they had to buy the complete truck and yank the cabs off. They appeared in rows at UNIMOG dealers - MEREX had a bunch of them. Many dealers did. When I looked at this guy's work and imagined how many man hours he must have rung up, those UHN cabs were such a deal...

OH, the guy titled his thread on his cab repair as 'MISSION IMPOSSIBLE', if that gives you any idea.


Anyway, here I'm just covering the front fenders and the internal beam structures that hold the Pivot pins for tilting the square cabs. I mentioned on the DOKA Cab lift thread how there is a slot formed between the beam and the sheet metal of the fender skin, and how it is a rust trap an so on. This thread will show some of that damage and how the guy dealt with it.

He changed his approach after fixing one side. He jumped on the right hand side of the truck and repaired the beam and the fender. For the left side of the truck, he cut to the chase, and lopped the beam and the fender straight off and installed new pieces, welding them on, after repairing the firewall.

Some notes -
He had to cut the lower part of the fender skin off to gain access to the lower end of the beam. There is no other way to really see what you are dealing with in there - maybe a hole saw and a borescope, but the bottom of the fender was rusted through, so his approach made sense, at first. Then, when he got caught up in making all of the necessary patch pieces, he changed his approach for the left side. Much less work to get to the end result, as you'll see.

Next, when you look at the outer surface of the exposed beam, it looks very clean, except for the bottom area, which is where the pin structure is located. The pin wasn't in too bad of shape in this case. I was surprised how clean the surface of most of the beam was, considering how bad the rust damage was in many other parts of the truck.
The inside of the beam (towards the engine) is well trashed, with a good amount rusted away.

After he repaired the right side, he purchased new pieces to tackle the left fender. When he got the new beam, he apparently discovered that it had been upgraded from the original pattern, with more structure added. He went back after the Right side beam and added the same sort of structure to it.
I'm pretty sure that if he has to do this again, he'd chop it all off and put new pieces on, as he did on the lefthand side.

I have to check, but the drain holes do not look to be the same as the ones I circled on the other thread. I'll put some photos side by side to compare them down the road.

So, I''ll post stuff in the order that he worked on it : Right Beam, Right Fender, Left Beam and Fender together.

It's boring to most, probably.

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Discussion Starter · #8 ·
P.7
Some additional shots of damage around the cab . I take these damaged areas as a cautionary tale, and photos like these have prompted me to go around pulling the side marker lights and whatever else looking for any sign of rust. So far, I haven't found any, but it is a good time to hit the hidden areas under the gaskets with polish and wax.
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Discussion Starter · #10 ·
The cab does not look like a real rust bucket, but it had rot scattered all over it.

Basically, everywhere that there was something bolted to the body rotted out and that area was cut out and replaced -
Plow lights lights above the windshield.
Lights at the base of the A-Pillars
Marker lights on the front roof sides
Stalk Marker lights behind the doors
The Threaded inserts for the exhaust stack, and so on.
Window gaskets all around and then the usual spots - the floor, the lower areas of the cab, the corners, etc.

They use a fair amount of salt, and the communal trucks generally plow and spread salt and grit in the winter, so they are getting dosed at work.


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2001 W163 ML270CDI / 2006 W164 ML500 / 1986 U1300L Unimog
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Yeah unfortunately my mog sat in storage for years while I worked away. It would appear when the military did one of the mission specific spray jobs they didn't replace the seam sealer in the gutters. This not only rotted out the gutters but the floor on both sides at the bottom of the B pillars and there also seems to be something going on at the bottom of the driver side A pillar too. It's going to be a full cab off job unfortunately. I think I'll take the opportunity to extend the roof and do a flat floor behind the seats while I'm butchering it. My only concern with removing the gutters is if it then lets water in at the top of the door.
 

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Discussion Starter · #16 ·
For some reason, I can't drag a hot link in here - computer obstinance. Here is the link, but it'll need to be typed in I think. At least it will be a direct route to the Mission Impossible rust fest.

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Yeah unfortunately my mog sat in storage for years while I worked away. It would appear when the military did one of the mission specific spray jobs they didn't replace the seam sealer in the gutters. This not only rotted out the gutters but the floor on both sides at the bottom of the B pillars and there also seems to be something going on at the bottom of the driver side A pillar too. It's going to be a full cab off job unfortunately. I think I'll take the opportunity to extend the roof and do a flat floor behind the seats while I'm butchering it. My only concern with removing the gutters is if it then lets water in at the top of the door.
That's to bad, that sounds like cab off would be the only good options. I have done some rough patching on my cab, but it will have to come off to do it correctly.
 

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Discussion Starter · #19 ·
Just some shots that show how 'the Slot' is obscured from view in the engine bay. On the Right side, the air cleaner, the washer tank and the hydraulic oil tank do a good job of covering it up. On the left, it is a bundle of air lines and some wiring that make a big loop towards the firewall (which is configured this way to enable the cab to tilt without binding up).
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Discussion Starter · #20 ·
When I was cleaning up my engine bay I went after the slots, looking to see if there was any debris in there. I used one of those spring clamp grabber tools and a length of fuel line taped to the nozzle of the shop vac to fish around between the beam and the fender skin, from top to bottom.
I did find some debris - leaves and other organic crud, but not a ton of it.
I kept at it until nothing was coming out, then I dribbled low velocity water from a garden hose into the slot to check the flow out of the drains. I didn't want to blast it with water out of a nozzle, because initially I wanted to be able to see if the water was coming out of the drains without restriction.
The first photo shows water flowing out of an opening at the front of the fender, next to the rod that catches the bottom of the grill.
Then, I used soapy water, a bottle brush, and a jet stream out of the hose to knock anything else loose. Then more fishing with the tools. Then paper towel chunks in the jaws of the grabber tool to dry things up, a little heat gun on low, and then a day or two of ignoring it on warm sunny days. Once I was pretty sure it was dry ( no signs of moisture on paper towel patches or chunks of shop rags), I sprayed a good number of doses of Loctite Rust treatment, with and without the pipe in the nozzle. ( I just found out that the spell-checker wants to convert Loctite to Lactate....the unseen friends at work).
That was it. It sounds a little obsessive, now that I write it down, but I was in the mode, and I didn't want to do it all again anytime soon. I couldn't figure anything else to do, and the truck is a clean example, so I moved on to other things.
Now, if I park it in the living room and never use it, I should have no worries.

The shot of the BW U1300L - if you look at 'The Slot' there looks to be a gasket stuffed in there. I've looked through a bunch of photos and have not seen that anywhere else, including on UHN cabs. It runs down the slant of the beam, and then horizontally across the bottom.
I don't know, but it isn't common.


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