Short style fuel pump

[Madmerc]

Hi all  my fuel pump started to leak so I purchase a rebuild kit off eBay and install it and it leaked even more after installing it . The main issue was the two o rings where the positive and negative terminals are  I found that the o rings were under sized  has any one had this problem before and is there any where I can purchase the correct o rings thanks

[DaveB]

Sounds frustrating. Member George Des may be able to supply the correct o-rings if you can't source them locally.

[Madmerc]

Thanks daveb

[perry113]

Hi all  my fuel pump started to leak so I purchase a rebuild kit off eBay and install it and it leaked even more after installing it . The main issue was the two o rings where the positive and negative terminals are  I found that the o rings were under sized  has any one had this problem before and is there any where I can purchase the correct o rings thanks

Do you mind sharing who the vendor was on ebay? I am in need of a rebuild kit for the same reasons being the pump is leaking from the O-rings where the electrical terminals are.

Vintage Euro sells them here
http://www.ebay.com/itm/SHORT-STYLE-FUEL-PUMP-REBUILT-KIT-for-Bosch-MERCEDES-W108-W111-W113-/262417362171?fits=Make%3AMercedes-Benz&hash=item3d194b2cfb:g:ekcAAOSw9NxTvxxq&vxp=mtr

Mercedes Source sells a  kit but it does not seem to include the O-Rings you and I need.
https://mercedessource.com/store/1963-1973-short-bosch-mfi-electrical-fuel-pump-resealing-kit-w-extras

There was someone also selling kits on Ebay from Plattsburg NY
http://www.ebay.com/itm/MERCEDES-NEW-Bosch-fuel-pump-0010915-seal-kit-W113-280SL-280se-250se-w111-w112-/111971984190?hash=item1a120ce33e%3Ag%3AGs8AAOSwll1Wulm0&vxp=mtr&nma=true&si=pGE1aEBkqabkbcUmspu9or%252FmVF4%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

It would be good to know what kits work and what ones are boat anchors.

[Tyler S]

If you dont need the brushes then the one from Authentic Classics is the best bang for your buck. If brushes are needed, use the one from Vintage Euro. I have used both in the past with no issues.


http://www.authenticclassics.com/Fuel-Pump-Seal-Hardware-Kit-late-Mercedes-280SL-p/auth-006328.htm

[Marrs]

Seems like these types of repairs always show up in groups. I just found my (short style) fuel pump to be leaking at, or rather behind, the wire terminals as well. When I disassembled my fuel pump, I removed the single bolt/washer that holds the red and brown terminal plastic base in place. From there the wires remain attached and it didn't seem like I would be able to replace those seals without disconnecting the wires themselves by de-soldering and then re-soldering after they are in place. Am I overlooking something that would allow me to more easily replace these specific seals?

Also, for clarification from the OP, were the seals under your terminal replaced as part of that kit but simply the wrong size, or were they left out and you realized after rebuilding that these were the culprits not the other seals? Are the smaller brown seals (3 pictured) in the Authentic Classics link the seals for the terminals? Thanks to all.

This is for my coupe.

[Tyler S]

Two of the three small brown seals in the Authentic Classics link are for the electrical posts. The third is a small seal used in the pump body between the 2 halves. It is not always applicable.
To replace the electrical post/terminal seals the pump really needs to be completely torn down to access the brush plate where the other ends of the wires are attached. Yes they need to be de-soldered to replace the o-rings.

[hkollan]

To replace the electrical post/terminal seals the pump really needs to be completely torn down to access the brush plate where the other ends of the wires are attached. Yes they need to be de-soldered to replace the o-rings.

Hi,

There is no need for a full tear down just to replace the terminal o-rings.
Loosen the terminal screw and slightly pull the terminals carefully not overstretching the Cable/spiral, desolder at the terminal ends, replace o-rings and resolder the terminals back and pushing them back in again, thighten screw and its done.

Regards

Hans

[Marrs]

Mine is already disassembled so no worry there but good to know options, thanks. What's odd is my pump was rebuilt only two years ago but I am thinking they didn't replace those seals, but I do have the part numbers of the seals that were used. If anyone happens to know the PNs for the terminal seals I would appreciate it so I can bring this up with my shop.

I did see that MercedesSource recommends a lubricant to help seat the seals without twisting or crimping them, but I'm not ordering their set, what is the proper type that won't degrade the rubber? I plan to use exceedingly sparingly to avoid or lessen contamination to the fuel. 

[Tyler S]

Vaseline works good

[Marrs]

I wouldn't think Vaseline would be ideal for this application as being petroleum based, it would likely degrade the rubber seals. A quick check online seems to confirm this. (Edit: I came back to say that I'm possibly off base here, as the pump and seals clearly sit in "petroleum based" fuel all day long.)

Also, if anyone should go the route of not disassembling the pump for this repair, you would still need to be very certain ALL the fuel and associated fumes are cleared from the entire unit well before soldering. (Note: You still need to remove the pump from the car after clamping off the soft fuel lines as removing the terminal screw will release the seal and allow fuel to pour out.)

[Tyler S]

I have tried the route of unsoldering the spring wires from the posts with the pump assembled. Its a crap shoot. The problem lies when you push the posts back into the pump. The wires can bend inside the pump in a way that they contact the moving rotor.

[Madmerc]

Hi perry it was vintage euro in clarita California

[Marrs]

I received my kit today from Authentic Classics, great folks to do business with by the way. They responded immediately to requests for info and are true gentlemen.

A question arose when I looked at the kit, on the attached diagram you can see item #5 is an o-ring but mine was not present upon tear down even though there is clearly an indentation within to accommodate the ring. When I watched the Mercedes Source video there was none present in that pump either, but who knows how much disassembly was done before the camera started. Being present in the diagram makes me believe the third small o-ring from the kit goes in that area as there is clearly intended to be one. Anyone remember the o-ring when you did your tear down? I am not confusing it with the o-ring that fits on the bottom of the post, that is #4 in the diagram.  The (*) on the description page indicates it is "used on some models" but does anyone know which models or what the purpose is, and why it's not necessary on others?

[Tyler S]

Maars, If you look at the center section of the pump (the one with the inlet fitting), you will see the area that this o-ring, if installed, rides against. If the hole is not through drilled into the supply chamber then you leave the o-ring out. You will see it may only be drilled a few mm deep then stops. If its drilled all the way through, add the o-ring. This was a change made to the pump at some point. In either case it is to allow fuel to bleed off of the upper electrical chamber of the fuel pump. Bosch just decided to bleed it off to a different area.