Fix/replace Fuel Pump

[rogerh113]

Hello,

I had some problems with my fuel pump not starting up when the ignition gets turned on, and it has recurred.  Time to do something more permanent by way of a fix.  The fuel pump starts right up with a slight tap on the input line, but not interested in this as standard starting procedure.

Any suggestions on whether to rebuild or go new??  I have a '66, but it does have the three support mount (I will have to confirm, but I am pretty sure), so the new pump may be easy to install.  Also, given the symptoms, would new brushes likely solve the problem??

Suggestions, experiences, and suggested vendors would be appreciated.  I would like to get after this soon, since I really like driving the car and I am sure this is not self-healing.....

Regards -- Roger

[Naj ✝︎]

Roger,
These pumps are fixable. You have to know which one you have, though.
Do a search on fuel pump theads by George Des.

naj

68 280SL

[rogerh113]

Thanks. I found the Des article and it was very informative.  The pumps may be fixable, but it seems that parts are no longer available.  Nobody seeems to sell rebuild kits, either old or new, and replacement bushes seem only available for the newer style fuel pump.  I think I have located a rebuilding shop, which I may well go with (and retain the original style pump).  Since new brushes are supposed to be good for 100K+ miles, I guess it should be good for a few years.....  Surprising that on such a popular classic car you have to go through unnatural acts and significant expense to effect a fuel pump repair - formerly I have only found certain trim parts impossible to get.

Thanks -- Roger

[hands_aus]

Hello Roger,
Is your pump the older pump?
I rebuilt my older style unit with great advice from George Des.

The cost for parts was about $15.00 including bearings and o-rings.
I didn't replace the brushes because they had about another 30 years of wear on them.

I wrote a report for myself as a future reference. Would you like a copy?
I will need a real email address as there is no way to attach files to the email feature of this site.


Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[mdsalemi]

Roger,

Before you mess with the pump itself, spend a few moments under the car and in your trunk and ensure that the electrical connections to the unit do not have compromised integrity.  Connections need to be clean; crimps need to have little or no resistance, and the wire has to be unbroken. Check the voltage as well.

You might have electrical issues outside the pump.  I did.

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[rwmastel]

quote:Originally posted by hands_aus

I will need a real email address ....

You could simply click on his username and send him an e-mail, introduce yourself, and ask for a reply.  This prevents the user from publicly announcing their private e-mail address.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[rogerh113]

Hello,

I would like your rebuild report - my email is mrheyderus@yahoo.com.  I did contact the sources in the Des posting thread, and nobody has the kit any longer, including the several sources I currently use for parts.  I did check the electrical integrity last month when I was trying to resolve the problem (and thought I had.....), and it all looked solid (including the fuse).

Thanks -- Roger

[George Des]

If there is a real need for one out there, I can put together a rebuild kit that will contain most of the parts you would need to rebuild the large style pump. There are two parts I can't supply--the bellows seal and the small in-line fuel filter. In such a kit, I can provide the 2-bearings, brushes, the main seal tab washer, shaft o-ring, and three larger o-rings. You'd have to reuse the side cover seals and bellows seal. Id' recommend all new fasteners, washers and a woodruff key which you'd be able to cut from some key stock. This would not be a BOSCH rebuild kit!

George Des

[rwmastel]

quote:Originally posted by George Des

You'd have to reuse the side cover seals and bellows seal.

What are the chances that reuse of these parts would lead to more fuel leakage?

quote:Originally posted by George Des

I'd recommend all new fasteners, washers and a woodruff key which you'd be able to cut from some key stock.

For those who are mechanically inclined, but have never done this before, would you be able to prvide a list of such hardware, or the hardware itself, with the "Des Fuel Pump Kit"?

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[rogerh113]

Well, I went ahead this morning and ordered a rebuilt longbody pump. They seem to know what they are doing, and are very familiar/specialize with vintage Mercedes of the 113 era.

I did (last month) pull the bottom off of my pump, and successfully reseal it (it is possible, but you do have to be careful, and I did have to use some gas-friendly Permatex from long ago).  Given how unpleasant it is to be towed, and uncertain as to how many times my wife will tolerate the garage smelling strongly of gas, this rebuild approace seems to provide a pretty high level of certainty.  I also like the rebuild approach - known good parts are retained, and quality current parts replace the worn ones (maybe better than new, depending on the skill of the rebuilder.....).

Given how difficult parts are to get now, those with aging pumps and a desire to retain their original, older style pump, may want to determine now how they are going to fix their pumps, and obtain the parts while they are only hard to get, rather than impossible.....  I was going to get a used pump on eBay, but I figured that was no solution as it probably had better than 100K on it and as such was only a short-term solution ('till it broke too).

Thanks for all of the help and offer of the kit!!

Regards -- Roger

[George Des]

Rodd

The kit I would propose would contain the parts I mentioned in my previous post. These are the parts that would be needed in most rebuild cases. In some cases, the bellows seal is gone beyond repair and the only solution is to replace it with a bellows that can be salvaged from another pump deemed otherwise unsuitable for rebuild. If the commutator is worn beyond being serviceable or the windings on it or the field coil are burned out, these can also be repaired. It is hard to say how long any of these rebuilds will last--most originals go for over 30 years when wear finally catches up with them. The major contributor to premature failure is abuse or lack of use. The major wear items are the brushes and the comm. Many good candidates for rebuild are inadvertently rendered "unrebuildable" when an inexperienced tinkerer attempts to do a rebuild.

In the end, the owner needs to decide whether originality is an  important factor or not--if it is, the rebuild is the only option for the replacement on the earlier Sls. If originality is less important than total piece of mind that he/she will not experience a pump failure, then the owner always has the option to buy a brand new smaller style pump that Bosch can provide with a full warranty. These are readily avialable through a number of sources.

George Des

[rogerh113]

Not sure how accurate the entire Des thread was, but it seemed that an early 230 owner commented that he bought a short body pump with the adapter kit, and could not fit the old fuel pump can over the 'new arrangement'.  Don't know if this is true or myth, but I would guess that having the can protecting the fuel pump is an important thing......

Regards -- Roger

[George Des]

Roger,
The fuel pump protector (shield) designed for the old style 230Sl feul pump will not work on the new style pump without modification. The inlet and outlet fittings on the two pumps are in completely different locations. The old shield can be made to work with the newer pump by cutting out a portion of the shield's side to allow passage of the fuel lines.

George Des

[mdsalemi]

quote:Originally posted by George Des

Roger,
The fuel pump protector (shield) designed for the old style 230Sl feul pump will not work on the new style pump without modification. The inlet and outlet fittings on the two pumps are in completely different locations. The old shield can be made to work with the newer pump by cutting out a portion of the shield's side to allow passage of the fuel lines.

George Des

...which explains why:

1) Used fuel pump cages without butchering are hard to find.
2) Many simply leave it off when it doesn't fit!

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[George Des]

Michael,

You are absolutely right. Most shops replacing an old pump with a new one leave the shield off and the pump exposed to the elements. Like you, I had spent many winters in New England and know what salt spray does to the bottom of a car. Combine this salt spray with an aluminum pump body held toegther with steel fasteners and you can understand why these pumps are just about impossible to disassemble to properly clean or rebuild.

George Des

[rogerh113]

This just seems to reinforce the importance of figuring out now how the 230SL owner wants to deal with their pending fuel pump issue (and it is pending).  I guess I am lucky that I have to deal with it now, rather than 5 years from now when a solution will be hard/impossible to find.  Even in California, I want that fuel pump can there to protect my fuel pump from rocks or other debris that could bring me to a halt on my long drives....

Regards -- Roger

[J. Huber]

For what its worth -- I have a later style pump on my early style car (63). My mechanic apparently did a little modification to the shield -- as it is there doing its thing. The bolts appear to be in the original location.


James
63 230SL

[hands_aus]

quote:Originally posted by rwmastel

quote:Originally posted by hands_aus

I will need a real email address ....

You could simply click on his username and send him an e-mail, introduce yourself, and ask for a reply.  This prevents the user from publicly announcing their private e-mail address.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

Thanks Rod,

As part of the discussion I invited roger to give the email address assuming that he would use the private email facility attached to our profiles.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Jazn]

quote:Originally posted by hands_aus

quote:Originally posted by rwmastel

quote:Originally posted by hands_aus

I will need a real email address ....

You could simply click on his username and send him an e-mail, introduce yourself, and ask for a reply.  This prevents the user from publicly announcing their private e-mail address.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

Thanks Rod,

As part of the discussion I invited roger to give the email address assuming that he would use the private email facility attached to our profiles.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

I sure would like a copy of the rebuild procedure and a rebuild parts list as well.
Thanks.