if it is, you will see it by pulling the false trunk wall out, and looking at it.
fixing it is easy, just hook up an air compressor to it, and put about 3 psi on there... it'll POP right back into shape. be sure and check for leaks once you do this though... crinkled fuel tank metal can fail.

Can it collapse in the opposite direction?

And, if there is a leaking issue, are the euro and US tanks the same? (I can't think of why they wouldn't be, unless US needed more room for emissions systems)

no, the shape of the tank is flat on the back side, and the front fits in the contour of the seatback, so it's pyramid shaped and very resistant to implosion from the front. if it's collapsed at all it'll be in the rear of the tank.

123 tank is a 123 tank, I've got 240's 300's euro and US... same... aside from volume... (240 tanks are smaller)

Alright, that is good to know! Many thanks!

If I've time tomorrow, I'll start experimenting with vacuum on the transmission to see what isn't right.. Fun days ahead!:rolleyes:

Your fuel tank probably looks like this one in this thread....

Why you shouldn't ignore a plugged fuel tank vent - Benzworld.org - Mercedes-Benz Discussion Forum

I didn't see anyone address this. The answer is no, that assumption is incorrect. Lack of vacuum will cause overly hard shifts. I do not recognize the VCV system in your photos that US market cars have so I cannot help with specifics for your car. But US spec cars have a valve that modulates vacuum to the transmission by the amount of throttle input - full vacuum at idle, nearly none at full throttle. Shifts get harder the less vacuum the modulator sees from the VCV.

More photos:
http://i865.photobucket.com/albums/a...pse5732bea.jpg
Looks like the tank isn't collapsed! Yay!
http://i865.photobucket.com/albums/a...g?t=1380766274
IP timing off from factory mark.
http://i865.photobucket.com/albums/a...g?t=1380766278
Whole setup
http://i865.photobucket.com/albums/a...g?t=1380766275
Importation info (1985 model manufactured in 1984)
http://i865.photobucket.com/albums/a...g?t=1380766279
Another (clearer?) photo of engine bay, driver's side.

Engine code: 617 912 12 162 197
Transmission code will come up later, I will edit this post when I have it. Will be looking into checking the modulator via this method, and hopefully that will be most of the problem...

Also, Secondaries, thanks! What you said makes me wonder if part of the system is missing, or the lines are hooked up backwards...

Cars not an 84 or 85 one tell tell sign is the vacuum controlled cruise control.....I am going to venture its a 1981.....I believe the vac controlled went away in 81 or 82....and they began to use the electric motor servo one.....bummer someone resprayed the car in a different color....

Is there any way to tell if the engine has been swapped? To my untrained eye, it appeared to be original (looked at it from both the top and the bottom).

And the car was originally black, as far as I can tell. I don't have much of a history on the car, other than that it was privately imported by the previous owner's grandfather. They did a terrible job repainting the car. As soon as I get everything in working order, I am going to start the 'strip and redo everything' method of automotive body repair...

I doubt your engine was replaced.....it has the euro type m pump on it.....I would imagine if it had a new engine swapped in, it would have been a standard us non turbo engine unless the block was changed by the dealer.....if you would have checked timing stretch before the replacement of the chain....that would have told you if it was a rebuilt engine or not.....a compression test may also tell....

that manufacture date is the stamping of when the car was imported to the US and "converted" to US requirements most likely. are there any other data plates on the car that could offer a build date from Germany?

I've got the VIN in several locations, though previous searches have proven to be pointless. It is the US style VIN, not the European, and when I paid for one of the $3 VIN things, it said it was an '85 model made in '84...

EDIT: I'll see if I can get the original purchase info from PO's grandpa.

I am still waiting on the info from the PO.

A new problem has developed. It is vacuum related...

When the vacuum is hooked up to the regulator on the injection pump properly, it creates an odd noise when running. I am not really sure what is causing it, but tomorrow I will start looking around..
I do know it is not related to the vacuum pump itself, because in a closed system, the vacuum pump doesn't make the noise.

If anyone has any ideas, help is appreciated! :o)

An update:
 

An update:
First owner said he purchased the car in 1984, in a town near Stuttgart, while on some sort of vacation.

There was something preventing the vacuum regulator thing on the injection pump from closing. Got whatever that was out, never found it. I think it was probably just a bit of dust.

Ended up replacing the screen in the tank, because it was only $2 more than just the seal, because of some kind of sale. There weren't any clogging issues with the old screen. I replaced the vent as well.

Still having transmission issues, can't seem to find where the issue starts.

Haven't done anything with the injector pump.

I have been thinking about troubleshooting my cruise control. Does anyone have any advice on where to start? All I know now is that it holds vacuum.