I have been having problems with water getting into my 300E fuel system, causing various running issues and the replacement of the fuel distributor, pressure regulator and other parts.

Finally, having decided to explore the entire fuel system in a bid to find the problem, my mechanic and I discovered that the charcoal canister in the left front fender is a mass of rust due to the drain hose from the runoff below the windscreen dumping straight on top of it.

So, it needs replacing and hopefully will explain why water is getting into the tank through the vapour system. We only ended up pulling the canister after we were unable to get a vacuum at the tank. There are no leaks in the actual fuel system in our checks so logic suggests air was getting in somewhere.

A subsequent check of my little used Haynes manual recommends replacing every 72,000 miles or 4 years. Problem is, I can't find the part in the online catalog and would like to know how much its likely to cost. Anyone help with this?

__________________
1987 300e manual 250,000 km (sold)

I got a price on one for my 560SL lately and it was $135.00 US. It also shows up in my Electronic Parts Catalog EPC. You may also want to change your purge and vent valves while you are at it, about $20.00 each.

J. Roncallo

It would be real unlikely for the cannister to be able to input water to the fuel system. There is a roll over valve between the tank and the cannister that only allows flow from the tank to the cannister. The cannister should be purged to the engine intake system.

Unfortunately a more likely problem is that over time for one reason or other the lining of the tank has been corrupted and the tank is now rusting ( the lining is a plating like galvanize). Look at your cap if it is original to see the corrosion. Once this takes place the only answer is a different tank. The most common cause of all this is disuse and condensation. A separate reason for the lining deteriated is too much alcohol in the fuel either due to poorly formated gasohol or too much octane enhancers.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

oh dear.

yes, have rust on the inside of the petrol cap. I've just had to braze a patch on the tank itself so i know for a fact its rusting on the inside.

however, there is water getting into the fuel system and I don't know how or why. the charcoal filter is a mass of rust, open at the top and bottom

one question: can I use a later model plastic tank to replace the steel unit in my 87 model?

__________________
1987 300e manual 250,000 km (sold)