Hi All - New member here.
Not an M-B guy, but helping out a friend who inherited a 1974 C280 Coupe.
I'm a Corvette guy, pretty mechanically handy, and active on their forum, so I know I can get a lot of good info here to help out my buddy with!

I helped him replace his top radiator hose this weekend. It had burst right at the top and caused a mess under hood.
When we tried to start it up for the first time after replacing the hose, clamps, and fluid, we couldn't get it to turn over.
Discovered it had no fuel going to the carb (looks like a 4-barrel).
Removed the rubber fuel line that goes from the pump to a "T-valve" right before the carb, and saw it had fuel pumping out of that when he cranked the engine.
Decided to prime the carb with a little fuel directly into the primaries, and got her to start. From that point on, it would start ok.
(not sure what would cause the system to lose its prime in only 3-4 weeks, and if this is normal?)

Main question, is that, after starting, I observed the fuel return line from that same "T-valve" (it's a fabric woven sheathed hose), looked like it was seeping fuel intermittently.
With the engine running, you could literally see the hose fabric "breathing" fuel in and out with internal pressure. Nothing really got to the point of dripping, due to the "inhaling and exhaling", and it would stop once the engine was running for a minute or 2. But it would seep again upon the next start-up.
Figuring this is not normal, but I'm not that familiar with 1970s German engineering.
I know this wouldn't be acceptable on my Vette, but I never encountered a fabric sheathed fuel hose before.
Does this mean the internal lining of the hose is shot?
Looks easy enough to replace, as it only goes from the "T-Valve" to a hard line down under the engine, where I see a hose clamp.
Looks like there is a similar hose from the supply hard line TO the pump, but I don't see any seeping from that, but know it's not under the same pressure as the post-pump line.
Would it make sense to replace both?

Would appreciate the input of this forum, so I can advise my friend if he has a hazard condition at all.
Wish I had pictures, which I know are valuable currency on these forums!

Thanks,

 

Really?
63 views and no replies?
This is my first post here, trying to help out friend, as I said.
Thought there'd be better responsiveness from this forum.
Over at the Corvette Forum, much more activity and replying going on - even just chatter, but mostly helpful posts.
Is there another M-B classic enthusiast Forum that would be better for me to post my question to?
Thanks,

 

Hello and welcome to the forum! I'm not too familiar with classic MBs, but our forum (link below) has a very active community, who specialize in classics. I'm sure they'll be able to assist.

Forum link