Fuel Pump

[alantlo]

Hi All:

New guy here. This is a fantastic website with lots nice folks providing invaluable info on the W113. Really appreciate it.

I took my 1970 280SL out of long hibernation 5 months ago. Ever since getting it serviced by my mechanic in June, there has been a high pitched continuous noise from the fuel pump, although the engine runs just fine. Do I have anything to worry about, or should I replace the fuel pump before it quits?

Thank you in advance for your advice.

alantlo
CA, USA

1970 280SL
2004 E430

[jeffc280sl]

Welcome to the group!

My fuel pump makes a whinning noise when running.  I think they all do it to some extent.

Jeff C.
1970 280SL 4-speed

[J. Huber]

Hey. Welcome to the Group. Is this high-pitched sound something you hear when the car is running? Reason I ask is, the fuel pump normally has a bit of a high-pitched whine to it prior to starting up. Afterwards, all I hear is blissful purring but maybe the pump is still running?

PS Jeff, before you call me a copycat -- I am a slow typer!
James
63 230SL

[alantlo]

Thanks for the replies.

The high pitched noise is there as soon as I turn the ignition key to the #1 position, and stays there after the engine starts, and is there until I turn off the engine. It's continuous and is pretty loud. I can hear it clearly while I'm driving. I've had the car for 14 years. I didn't notice the sound before.

alantlo
CA, USA

1970 280SL
2000 E430
2004 LS430

[Naj ✝︎]

alantlo,
If you have the earlier old style taller pump, the bearings may need replacing.
George Des / Brisbane Bob are the resident experts on how to rebuild this pump. If you do a fuep pump search, there is plenty of info on the site.

naj

65 230SL
68 280SL

[rwmastel]

Yes, the electric fuel pump is the sound you hear and they are noise makers.  If you've had your car for 14 years and this is a new sound, then you should probably look into replacing or rebuilding the pump so you don't get stranded at a bad time or location.

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

[George Des]

Atlanto,

As Naj pointed out, if this is the old style pump, it could well be the bearings--these are two--a 626 and a 627--those are the numbers for them. It could also be that there is considerable crud in the bottom of the pump section--perhaps something metallic that got past the inlet pump screen and has caught up between the vane and the bottom plate. Mnay would be surprised how many pumps I find that do not have this inlet filter or the radio suppresion capacitor! If it is this and your pump is in reasonably good shape i.e. the screws on the bottom plate aren't corroded badly, you might try removing the bottom plate and cleaning out this section. I only advise doing this if the screws aren't corroded and unscrew easily, otherwise you may find youself with several broken screws, the bottom plate still in place and no further along than when you started. If you get the bottom plate off, clean it out and it is still noisy, then Naj's diagnosis is probably correct--if that's the case, take a look at the many posts on this site and read up on what is involved in a large pump rebuild--it's not that difficult but you do need to know what you are doing or you will definitely end up destroying a pump that may be able to be rebuilt.

George Des

[Cees Klumper]

I don't think you should be able to hear the fuel pump after the car starts up, or at least not as you are driving along. Definitely sounds (pun intended) like it needs some service. I do think it is normal that you can hear it when you turn the key to '1' etc.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[alantlo]

My car was built in March 1970, so I would think it came with the newer style fuel pump (I’ll need to check to make sure). Does the newer pump have different bearings?

I’ll have to see what is involved in rebuilding the pump. If special tools are needed, I may have to send it out for the rebuild. Any recommended shops in Southern California that will do this?

Thanks.


alantlo
CA, USA

1970 280SL
2000 E430
2004 LS430

[A Dalton]

http://www.rockauto.com/ref/Carter/DetailPump.html?CARTF.EPUMP.PI.P60504.jpg

 $49..

[George Des]

There are only bushings in the newer style pump--no grooved ball bearings like in the old style pump. If it is the newer style and it is noisy, it could well be that the bottom plate, vane or pump housing bearing surface is scored or has a bunch of crud in it. This same condition can exist with the old style pump as well. You won't know until you open it. The newer style pump is much easier to rebuild but is also available new--its' very expensive--about $474-$500!

George Des

[A Dalton]

I had a newer style that was noisy as hell and it turned out to be one of the brushes had worn to the point of cocking in the holder.
So. the sooner you look into it , the better... like George said, Big $$$$ if you let them go beyond repair.

[alantlo]

Thank you all for your kind responses. I'll get on it ASAP.

alantlo
CA, USA

1970 280SL
2000 E430
2004 LS430

[alantlo]

Miller's has a fuel pump repair kit # 230-050K. Is this the one to use for the small style pump? Their picture shows the kit contains 2 brushes and 3 o-rings. Is this all I will need? I read somewhere that more o-rings would be needed. Where can I get those?

Alan
L.A. CA

1970 280SL
2000 E430
2004 LS430

[George Des]

Atlanto,

Provided your commutator is not too badly worn--this will be pretty obvious once you get the pump apart and take a look at the rut that the brushes will have worn into the comm- and other parts such as the vane are not broken, the repair kit has most of what you will need for a small pump rebuild. You can do yourself a great favor by replacing all the slot headed screws with hex head bolts and lock washers--M4x16--you'll need six of these-- should do for the bottom cover plate and M4x12 (Qty 3) should suffice for the motor to pump body attachment. Replacing with the hex heads will ensure you can easily remove again if you ever have to. Your first big challenge wil be getting the existing screws out w/o breaking them off--if you do break some, some of my earlier posts should provide you with info on how to proceed. Good luck and let us know how you make out.

George Des

[alantlo]

Thank you all for your support, and special thanks to George Des for his great advice and detailed instructions. You guys are awesome and I am very grateful. I have only driven the car 250 miles since I first noticed noise back in June, so hopefully the damage to the commutator is not so severe. I will keep you posted when I get a chance to put my hands on the pump.

Alan
L.A. CA

1970 280SL
2000 E430
2004 LS430