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Should I get the metal or rubber diaphragm rebuild set for my 350SLC's fuel distributor?

385 Views 5 Replies 4 Participants Last post by  Petrolhead350
Hi all, i'm new on the forum, so nice to meet you :)

I'm rebuilding my 350SLC's fuel distributor because the control piston was binding and the o rings around the metering slots were cracked and leaking. I've seen two variants of rebuild kits on the market; one with a stainless steel diaphragm as originally fitted on my distributor (so called 1st gen) and a variant with a rubber membrane.(so called 3rd gen. A 2nd gen set doesn't seem to exist) The sets seem otherwise identical.

What option should I go for, and does anyone know why two variants are available? I guess the 3rd gen rubber variant was an improvement, but i'm a bit reluctant with the ever increasing ethanol concentration of our precious petrol.. I guess this question has been asked before, but I couldn't find it on this forum or on google.

Anyway thanks!
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I would think the 3rd gen is cheaper to manufacture, and hence the change. If it was mine, I'd go with the stainless, especially with you having to buy fuel with ethanol. I'm glad I can still buy real gas in this State. California and a few other states have ONLY ethanol gas available.
Right, so no reason to go with the 3rd gen then I guess. Prices vary wildly between shops, but there doesn't seem to be no price difference between the two variants. Here in the Netherlands, ethanol free petrol is still available, but it's getting more scarce and is much more expensive. Being a gas guzzler that the 350 is (at least fo EU standards) I think it'll be on a strict diet of ethanol fuel, so the metal diaphragm seems to be the best option.
5 years ago I had a problem with one of my cylinder constantly carbon up and now firing well on my 1980 450SL. I replaced the injector and seals and still the same. I purchased a kit from CIS-Jetronic for around $100.00. I never did this before but watching videos on the subject and talking to someone from CIS, I was able to fix my problem by rebuilding the fuel distributor. I'm no mechanic by any means. I believe as its hard to remember but some of the 0-rings were really bad and some other components were faulty.
Thanks, good to hear. I was expecting similar issues regarding coking up of the engine, so for that reason i've preemptively replaced the injectors and rubbers in the manifolds. Distributor's looking nice except for the rubber seals, so I hope it'll function fine when rebuilt put together again. The only thing i'm a little concerned about is those little sieves/filters in the distributor's head. You can't seem to buy or replace them, and they might've gotten gunked up or broked down. can't really see. I'll just hope the cleaner did its work. we'll see.. :)
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