300SEL Fuel Pump Leak - Mercedes-Benz Forum

 
LinkBack Thread Tools Display Modes
post #1 of 2 (permalink) Old 07-09-2005, 08:41 PM Thread Starter
BenzWorld Newbie
 
kennodes's Avatar
 
Date registered: Dec 2004
Vehicle: 69 300SEL
Location: Brisbane QLD Australia
Posts: 3
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
300SEL Fuel Pump Leak

Hey fellow Benz lovers,

I have a small problem which I’m hoping one of you 108/9 knowledge ponds may be able to assist in solving.

Yesterday, as I was about to head off on my weekend drive, I noticed a fairly steady leak of petrol from the rear fuel pump of the car (69 300SEL 3.5.) It is still running and isn’t noticeably underpowered; however I have no desire to drive her anywhere until this issue is resolved.

Upon closer inspection the leak is coming from where the power leads join to the pump (See attached image if it works). However no cracks are immediately visible; that’s not to say they are there though.

Can anyone tell me whether?
1. The small cap which the power leads attach to screws into the pump, and thus there may simply be a deteriorated seal at fault?
2. If I could use the same fuel pump from a 280SE 2.8 or 3.5 of similar vintage if the issue is terminal?
3. If using a simple sealant would in your opinion provide a decent temporary fix?

Being a poor uni student, I’d love to save the AU$500 it will cost to get a replacement pump!

Thanks in advance for your help.
John
Attached Images
 
kennodes is offline  
Sponsored Links
Advertisement
 
post #2 of 2 (permalink) Old 07-09-2005, 09:50 PM
BenzWorld Junior Member
 
austinado16's Avatar
 
Date registered: Apr 2005
Vehicle: 1966 250SE Coupe
Posts: 30
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
RE: 300SEL Fuel Pump Leak

I'm not familiar with your specific pump, but I did just repair the one in my '66 250se Coupe 2 days ago and it was doing basically the same thing...although it has a "weep" hole (actually a little pipe) in the side and that's where the fuel was dribbling out.

My guess is, that like my pump, yours has an internal seal that's failed and you're now getting fuel all the way up into the electric motor portion of the pump. That's kind of exciting isn't it! Good thing that fuel and air have to mix at a certain ratio in order to combust with a spark present......KA-BOOM!

Anyway, I carefully took mine apart, replace one tiny little 6mm diameter metric o-ring and it's good as new. Total cost for that o-ring and the other one I replaced around the impeller base, $3.90US.

You should be able to FINISSE that pump apart, figure out where/what's leaking and then repair it. Mine had a neat little copper bellows style spring that was moulded into a bronze bushing at one end. The bushing ran on a carbon seal, just like you find in a water pump. Cool design. At the other end of the bellows spring was another bushing which sealed against the electric motor shaft with the little 6mm o-ring. This was all held in place with a tiny metal ring in a recessed groove on the motor shaft. It was a real job to get that ring off, but some tiny jeweler's screw drivers did the trick without breaking it or sending it flying....or scratching the shaft, etc.

Since yours is basically ruined, you have nothing to loose, so take your time and be creative and VERY careful!
austinado16 is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > General Mercedes-Benz Forums > Vintage Mercedes-Benz

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











  • Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
     
    Thread Tools
    Show Printable Version Show Printable Version
    Email this Page Email this Page
    Display Modes
    Linear Mode Linear Mode



    Posting Rules  
    You may post new threads
    You may post replies
    You may not post attachments
    You may not edit your posts

    BB code is On
    Smilies are On
    [IMG] code is On
    HTML code is Off
    Trackbacks are On
    Pingbacks are On
    Refbacks are On

     

    Title goes here

    close
    video goes here
    description goes here. Read Full Story
    For the best viewing experience please update your browser to Google Chrome