Why is the hose leaking? are you sure that the metal pipe going into the head is not rotted out?. for a temporary "Ghetto" repair, you might try removing both hose clamps and wrapping the hose with good quality duct tape, and uses four clamps to secure/reinforce it. pure ghetto, but it may[or may not] buy you time.

where is it leaking from? Try tightening the hose clamps first and see if that helps.

You can replace the hosewithout removing the pump if you buy the mb part (not oem - too stiff), and you are very patient about working the hose through the narrow gap with blunt tools. There isn't much room but a couple people have been able to do it. Replace both hose clamps, and be aware that all that trauma to the hose will probably shorten its life.

Another option is taking a hacksaw to one of the pipes and cutting off a quarter inch or so to give yourself more room. Be sure not to let any filings into the water passages (!).

Finally, the water pump r&r isn't too bad, it just takes a lot of time. If the belt has to come off, be prepared to replace the belt tensioner.

I saw the other thread and considering the quite broad nature of the question, I thought the responses were very helpful to guide you to looking at the right places to find the leak.
To do it right the water pump needs to come out to replace it. It's a job that requires a little competency and expect to run into [at least minor] problems while doing so. It's one of those jobs that will have you cursing out mercedes, but once you've finished you'll be saying it wasn't really that bad and it would take you a quarter of the time next time you do it.
These hose don't usually go "bad" but can develop leaks so if you're looking for a temporary solution, I agree with workerunit and tighten/readjust/add clamps. Carefully "feel" the hose to see where the nipple ends. The nipple coming out of the head extends to within about a 1/4" of the outlet on the pump, so you should have enough room to set another clamp on the pump side of rusty one in your picture. There is a flare on the end of the pump outlet and that clamp usually rests right up against the flare, but that side is probably sealed okay. You also have enough hose on the head side of the rusty clamp that you might be able to add a clamp there as well. The nipple is pretty heavy gauge so I doubt it's rusted through, but it may be pitted. As said this is an ATTEMPT at a temporary solution. Since your leak is minor, this is probably all you'd need to get you by for a while.
As far as being able to put a new hose on without removing the pump, I'd say it's very doubtful and if possible it might totally depend on how much space there is between the nipple and the pump outlet, which, while it may vary some, it's usually only about a 1/4". I tried (for the hell of it) to do it when I did my head gasket and found that for all the trouble I was having to manage it (if it would have ultimately even been possible) I'd just a soon take the pump off. One of the big problems, even if you can get the hose on part way is that you'd need to slide it all the back onto one side or the other to get the hose fully on through the narrow gap and then slide it onto the other side. The problem is, the pump outlet is too short (and wider than the nipple side) to slide on that side first. The nipple is long enough but the intake manifold is too close to it to allow the hose to slide back much further than it is sitting right now.
I thought about cutting the nipple shorter when I had the head off to facilitate being able to do this later, but I concluded that these hoses almost never go bad and taking the pump off isn't that big a deal once you know how to do it. If they do develop a leak, readjusting/tightening the clamps should take care of it.
Just my opinions.

Edited to add: anthonyb is correct, the MB hose is somewhat thinner walled than the aftermarket hose (at least the ones I got). And you are likely to need a new belt tensioner, they're not a longevity part.

Thanks for ALL of the replies.

I am not sure why its leaking... maybe because its almost 22 years old. Not sure if its ever been changed.

To answer someone else question, its actually leaking on the right hand side (not the side that looks rusty). I felt under the hose and the coolant leaking was on that side.

I really cant afford a costly repair now by having the pump removed/replaced, and I am not mechanically inclined, so I think I will take a trip down to my Mercedes dealer tomorrow and get the hose I need and attempt to change it. I just hope I dont get the old one off and cant get the new one on! That would be bad! We tried tightening the clamps, but they would not budge. I hope I can just get them off.

I know a mechanic that works on cars, (mostly European cars), so I am sure he could do it easy. I may see if he will change it for me. Be a good time to get that green coolant out too, but that may have to wait a couple of weeks.

Thanks again.

To get the old hose off, it'll have to be cut off. Once it's cut off, you ARE committed. I'd say it's nearly a sure bet that you (or your mechanic) won't be able to wrangle a new hose on it without taking the pump off. Expect at least a $150 bill for taking the pump off to do the job (if you won't need a new belt tensioner, add about $125 more if you do).
No offense, but if your stuck just trying to loosen the clamps you're probably not a candidate to remove the pump yourself, so I'd get the mechanic and instruct him that you only want to try and remove the clamps, possibly reposition/rotate the hose and put new clamps on it (and get that antifreeze changed). See if that works before proceeding any further.

86560SEL, apply some rust cutter to the clamp threads, then use a nut driver to break the threads free. Try tightening both clamps a bit to stop the leak. Replace the short hose when you have the time and money.

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Fred Hoelzle