Short Sttyle Fuel Pump Rebuild

[PeterPortugal]

Gents,

I bought a used short style pump on ebay for 150 GBP. It looked great but the seller said it didn't work because old gasoline had set in it.

The reality was an impeller with a missing vane (George Des or Baron Bob mentioned this was a common con trick).

On the plus side I have a spare impeller and the pump looked in very good condition otherwise. I decided to open it all up and have a look and it's not at all bad. the brushes look nearly new and it was pretty clean.

My specific questions are:-
1. In the attached picture is the stuff on the outside diameter of the motor old gasoline which should be cleaned off? If so what is the best method?
2. Are you supposed to lubricate the top bearing with a bit of grease or is it lubricated by the gasoline in the motor housing?

Regards

Peter

[BaronYoungman]

so no lubrication needed on top, the gas itself acts as lubricant.  But unfortunately the reason all the glue is coming out from the armature is because it was overheated at some point (either it was run for awhile with no gas surrounding to cool the armature or the gas was trapped in the pump and just heated up) I doubt this armature will function properly once it heats up, more than likely it will start shorting and run slow or stop. It is ok for the small magnet ends to not be lined up in a horizontal line from the side but must be lined up in a vertical line when looking straight at them, but glue should never be oozing out. Sorry Bob

[PeterPortugal]

Hi Bob,

Thanks for the response. As I am in the market for a couple of impellers when you are able to get them to the market have you a spare armature you can sell to me too?

Regards

Peter

[BaronYoungman]

YES, I am still on long term tests on impellers I have switched to TITANIUM... yes... titanium it will never corrode or warp and it is lighter so will spin faster. As soon as done anyone I have promised them to I will sell to.
Bob
and I do have rewound armatures available

[mrfatboy]

I just saw this impeller on eBay. 

https://www.ebay.com/itm/SHORT-STYLE-FUEL-PUMP-IMPELLER-BOSCH-280-SE-SL-MERCEDES-W108-W111-W113/223493689679?_mwBanner=1&ul_ref=http%3A%2F%2Frover.ebay.com%2Frover%2F1%2F711-53200-19255-0%2F1%3Fff3%3D4%26pub%3D5574895690%26toolid%3D10044%26campid%3D5336639833%26customid%3Dgeoship_email_api_advanced%26mpre%3Dhttp%3A%2F%2Fwww.ebay.com%2Fitm%2FSHORT-STYLE-FUEL-PUMP-IMPELLER-BOSCH-280-SE-SL-MERCEDES-W108-W111-W113-%2F223493689679%26srcrot%3D711-53200-19255-0%26rvr_id%3D1946161992869%26rvr_ts%3D5221e88516a0a8600970b478fff70eea&ul_noapp=true&pageci=e8af2be9-a88f-456f-8326-349ce97b8aec

[BaronYoungman]

Yes done by Babak at Vintage Euro Parts .  Aluminium and not chromed centers.

[dirkbalter]

I made an impeller model for possible manufacturing a while back. (I took the dimension of a broken one with missing fins). The impeller offered on e-bay seems to have a lot less wrap around the drive shaft. The original one has approximately 250 degrees. The one in the picture has a maximum of 180 degrees, loosing most if not all of the shaft to impeller accuracy or fit. It relies mostly on the impeller flat to align and center the drive shaft. I would be a bit worried about that, especially in the long run.

[BaronYoungman]

Dirk the PDF file was empty.  Bob

[dirkbalter]

Bob,
It's a 3-d pdf. It looks OK when I open it. I attached a jpeg.

[PeterPortugal]

I am still waiting for the titanium version....with chromed centers.

[PeterPortugal]

Gentss,

A couple more questions. Regarding the washers (shims) associated with the rotor. As I have a pump which has been messed with how do I actually know if the various washers were correctly fitted in the right locations?

There was a single thick washer in the area between the impeller and the lower bearing. there were three fine washers on the motor side of the lower bearing, Two metal with a plastic (fibre?) one in between them. At the top end of the motor there were two washers. One was a fine metal one identical to the others but the second one was copper and dimensioned slightly differently. It looked odd to me, see attached picture.

Is there a way to check the build and then shim accordingly?

Also what are the three small (half an inch or so) o-rings for which come in the typical rebuild kits?

Regards

Peter

[BaronYoungman]

These are used to center the pick up on the brushes. I will try and get a drawing together to explain.  There are from what I have found fiber ones, thin steel and thicker steel ones. you should never have a fiber one next to a e-clip. Bob

[PeterPortugal]

Hi Bob,

Thanks for the clarification on the fibre washer not being next to the clip. That make sense.

If you do have a drawing it would be good to add it to the article written by George Des in the Technical Manual?

Regards

Peter

[PeterPortugal]

The three small unidentified o-rings are for sealing behind the terminals. They must have thrown an extra one in by mistake.

[LWB250]

Great information in this thread, everyone. I have a question regarding repairs to a short fuel pump:

My pump stopped working recently. I tore it down and discovered that both brush holders had broken loose from the end plate they are attached to. It appears that there were metal tabs that were twisted to hold these in place.

A victim of the failure was one of the brush springs, unfortunately.

I have reattached the brush holders to the backing plate using a very strong chemical resistant epoxy. Now I am trying to find a brush spring, if possible. Would anyone know of a source?

I did get a rebuild kit and have everything I need to reassemble once I can source a brush spring.

Thanks!

Dan

[BaronYoungman]

Dan the springs are matched so you need to make sure you use the same tension on each side, there seems to be 4 different styles(tensions) if you can take yours out and send me a pix against a mm ruler I will see if I have a match.  Now, just a FYI I have used many different epoxies and because that part of the pump is in gasoline (with ethanol) 24 hours a day 365 days a year, I have not found something that does not eventually give out unless it has substantial "legs" left over from where it broke.
Just for anyone reading this the way these brush holders usually break is if the armature is pulled up without pulling the brushes back and the brushes get hung up in the ridge created by use of the armature although they can break in other ways.
Bob
baronyoungman@hotmail.com

[BaronYoungman]

Dear Peter,
As for the extra  small 0 ring, two are for the electrical connections the last one is if you have a early short style pump with a "bled through" hole.  Most pumps don't.  The easiest way to tell is look at the electrical piece and you will see an indent on the underside for the O ring (all pumps have this even ones that do not need o ring)  , then look at the corresponding inlet piece.  You will see a small hole, see if that hole is filled in (newer style) or goes all the way through to the fine mesh of the inlet screen.  If that hole is open (you can use a light if you don't want to chance poking a hole in the mesh) then you need to use the gasket otherwise it is not necessary and worse sometime falls off in reassemble and will eventually stop up the pump.

[LWB250]

Dan the springs are matched so you need to make sure you use the same tension on each side, there seems to be 4 different styles(tensions) if you can take yours out and send me a pix against a mm ruler I will see if I have a match.  Now, just a FYI I have used many different epoxies and because that part of the pump is in gasoline (with ethanol) 24 hours a day 365 days a year, I have not found something that does not eventually give out unless it has substantial "legs" left over from where it broke.
and just for anyone reading this the way these brush holders break is if the armature is pulled up without pulling the brushes back and the brushes get hung up in the ridge created by use of the armature.
Bob
baronyoungman@hotmail.com

Thanks, Bob!

I'm a former generator guy, so I know how to disassemble a motor - I totally understand the issue with the ridge on the armature. In this case, I surveyed the interior of the motor before I removed the armature, and one of the brush holders had broken completely loose from the plate they are mounted on. This was the failure mode for the pump, as it died while on the car.  The other brush holder was intact but I found after disassembly that it too was loose on one side. The armature is in good condition and the bars are still somewhat undercut as well, so it has minimal wear on it.

With your comments regarding securing these with an adhesive of any kind well taken and a concern I had as well in regards to the longevity of the repair, does anyone have a "junk pile" somewhere with a motor housing that would have intact brush holders? The remainder of the pump is in excellent condition. I hate to scrap it when all I would need is a cover with good brush holders in it. I can see from the construction of the cover and plate the brush holders are mounted on that attempts to remove it by grinding off the peened pins would probably render it useless.

Thanks again for your assistance!

Dan

[BaronYoungman]

Dan,  Many things can cause pressure (even an unbalanced brush or out of round armature due to gas residue) or debris and will cause those folded legs to break, they are way too fragile, I did not mean to imply anything, I just broke enough on my own that I wanted to warn everyone.  As to a solution, what I have seen that works is that if you dremel off the rivets holding the plastic (fiberboard) part and then screw using small machine screw and nut the brush holders from where the legs use to be to the fiberboard and then screw  with a sheet metal screw the entire fiberboard part back after drilling through the bottom of the electrical part and then dremel off the screw ends on the underside of the electrical part so they are flush.  I am sorry if that is confusing.  I have not tried it myself but have seen some fixed this way. I will try and find one that I can take a picture of.  As for extra ones without broken holders I do not have any, sorry.  But with patience and the right tools and hardware I think you can repair yours.
Bob

[LWB250]

Dan,  It is entirely possible that any pressure or debris will cause those folded legs to break, they are way too fragile, I did not mean to imply anything, I just broke enough on my own that I wanted to warn everyone.  As to a solution, what I have seen that works is that if you dremel off the rivets holding the plastic (fiberboard) part and then screw the brush holders from where the legs use to be to the fiberboard and then screw the entire fiberboard part back through the bottom of the electrical part and then dremel off the screw ends on the underside of the electrical part so they are flush.  I am sorry if that is confusing.  I have not tried it myself but have seen some fixed this way. I will try and find one that I can take a picture of.  As for extra ones without broken holders I do not have any, sorry.  But with patience and the right tools and hardware I think you can repair yours.
Bob

Bob,

Again, thanks for your insight!

I had wondered if the approach you describe was an option, as I wondered how the brush holders could be reattached without shorting them to the case of the motor when the fiberboard was reinstalled. The commutator is wide enough that even if you raised the brush holders a small amount the brushes would still be well within the range of the commutator, I would think.

As for fasteners, they would have to be rather small, wouldn't they?

Pictures of such an approach would be very welcome if you have any. I'm in no hurry, so please don't rush this - the car is currently out of service right now with the rear axle being refreshed.

Again, thank you!

Dan

[BaronYoungman]

Dan, I believe you are right on that you do have some room to move up, but if they are moved too far up too far then the armature lower end (half moon) will not fit entirely inside the impeller and that will cause a issue as the impeller ages and is compacted by the steel half moon armature. As I sit at my desk, wishing I could be working on my mercedes, I am thinking maybe you could use a plastic screw and nut (or will they get eaten by the gas) to hold the brush holders to the fiberboard then screw the entire fiberboard to the electrical holder.  The reason they use the fiberboard with isolated rivets is to not ground them out to the body of the pump.
Just thinking, Bob
Now back to banking..... YAWN! snooze

[PeterPortugal]

Bob,

Thanks for your response about the third o-ring and the PM you sent.

I have to say (despite Dan's woes) that these later style short pumps are a massive improvement on the earlier tall style on terms of ease of repair. My car should have a tall style pump but I have given up trying to seal the two I have rebuilt !

Regards

Peter

[LWB250]

Good to know, Peter. I've never dealt with one of the tall pumps, so I don't have that experience to reflect on.

Bob's suggestion about the plastic fasteners through the fiber board sounds quite possible. Not only that, the use of plastic fasteners would preclude the concern about any electrical issues with fasteners going through the brush holders and coming into contact with the pump housing.

I'm going to research this further (meaning a trip to my local Ace Hardware and the aisle with the "magical drawers" of unique hardware) and see if I can affect this repair. I'll document it in a separate thread so as not to hijack this one any more than I already have (sorry!)

Again, thanks to all for the input and sharing of knowledge. It's what makes these forums great!

Dan

[PeterPortugal]

Dan,

If you get google translate on the case this is quite a useful article to look at.

https://www.mercedesscheune.de/index.php/vollrestauration-w111-coupe/step-5-motor-achsen/benzinpumpe-restaurieren#g_1_5

Thanks to "Mercedes Scheune" (if you are a member I hope you don't mind me sharing !!)

Regards

Peter

[LWB250]

Thank you, Peter!

Dan