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Gregory

USA
62 Posts

Posted - 01/12/2007 :  16:28:10  Show Profile  Reply with Quote
nevermind, the 3.5 pump works.
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Ron B

Australia
11611 Posts

Posted - 01/13/2007 :  06:23:08  Show Profile  Visit Ron B's Homepage  Reply with Quote
If you want to fit the 3.5 pump.be aware that the neg and positve terminal must be wired up correctly or it won't pump.It will run but won't work.
Try and use the entire pump assembly including the noise damper and filter because it features a fuel return systym which prevents vapour lock bubbles .

The bracket in it's entirety is also useful but will need some sort of bracket to drop it down so the fuel feeds in from above,same as the stock 6.3 pump.You can use the W116 or W126 pump which has identical bracket arrangement but they have a fuel pressure accumulator which can be deleted.

...There are old cars,and then there are Classics..(Mercedes Benz Ad. 1999)
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Gregory

USA
62 Posts

Posted - 01/24/2007 :  19:28:36  Show Profile  Reply with Quote
I ordered the reseal kit for the pump; it should be here tomorrow. Does anybody know if the kit comes with the o-rings for the positive and negative terminals?
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Chris Johnson

USA
3751 Posts

Posted - 01/24/2007 :  22:40:18  Show Profile  Reply with Quote
Just a quick comment.

I rarely get into the late style horizontal pumps, but I doubt that fuel should even be able to get to the point where it is coming out past the wire terminals.

If this pump is anything like the original style pumps, there is a seal between the fuel section and the motor. This seal is not just a simple O-ring. This fault is what generally puts these pumps in the hands of a professional rebuilder.

The point is to make sure you have a good seal between the fuel section and the motor, otherwise, you may be creating a bomb!

Chris Johnson
If you aren't constantly IMPRESSED with your car, then it needs fixing.
100.012-12-000790
109.018-12-000019
109.018-12-003834
www.300SE.org
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Gregory

USA
62 Posts

Posted - 01/24/2007 :  23:03:28  Show Profile  Reply with Quote
Sorry, I was not clear. The pump I am talking about is the "short" version pump. The second version, for the 6.3. Not the 3.5 pump.
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Chris Johnson

USA
3751 Posts

Posted - 01/24/2007 :  23:23:26  Show Profile  Reply with Quote
The same rules apply. There should definitely be a seal between the fuel section and the motor.

Chris Johnson
If you aren't constantly IMPRESSED with your car, then it needs fixing.
100.012-12-000790
109.018-12-000019
109.018-12-003834
www.300SE.org
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Ron B

Australia
11611 Posts

Posted - 01/25/2007 :  03:25:40  Show Profile  Visit Ron B's Homepage  Reply with Quote
Chris on the earlier long pump there was bleed hole which allows the fuel to run out if the seal fails,but for a reason known only to Daimler benz and Bosch ,the short pump doesn't have this hole and it is deemed uneccesary to have it.I have pulled a few apart and found the white stuff you used to get when water and petrol mixed together, in the amature windings.But they never caught fire,A lack of air would explain that I think.Better than having raw fuel dripping,and vapourising on the road from a dodgy pump.

...There are old cars,and then there are Classics..(Mercedes Benz Ad. 1999)
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Gregory

USA
62 Posts

Posted - 02/08/2007 :  18:05:47  Show Profile  Reply with Quote
So I resealed the pump, and not to my suprise, it's still leaking at the terminals through the orings that I did not change. I was not able to order them from the dealer. I think I need to unsolder the connections and find some o-rings of similar size. I also believe fuel IS supposed to be in the armature area; I don't think it is supposed to be a dry area.
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George Des

USA
11 Posts

Posted - 06/27/2007 :  17:24:45  Show Profile  Reply with Quote
Gregory,

You are correct. Unlike the long older style pump, the smaller pump has no sliding ring seal isolating the motor section from the pump section and is designed to have fuel flowing through the top "motor can" section-thus no leak off pipe. The fuel flow cools, cleans and lubricates the motor section of the pump.

The original o-rings used on the terminal section have a flat cross section, but you should be able to get a standard o-ring of correct size to work as well. These o-rings are not included in the MB repair kit. (I've been considering building kits for both this pump and the older pump that would provide more than the MB kits but have just not got around to it.) What I generally do is use the std o-ring and help it seal up with some gasoline resistant sealer--comes in the yellow tube with red writing and available at Autozone or Advance Auto. Make sure you put the "motor can" and impeller vane back in exactly as they were or you'll have a pump that operates in reverse or won't pump fuel or both. See posts on this on the Pagoda site--it happens quite often and drives people crazy trying to figure out what is wrong.. Hope this helps.

George Des
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karra

Finland
862 Posts

Posted - 06/27/2009 :  05:41:15  Show Profile  Reply with Quote
Hello!

I had two different breakdowns today . After having filled the tank of my 6.3 I saw few days later some fuel had leaked out. I thought the fuel expanded when our weather warmed up from 15 to 28 deg C. The problem was leaking fuel pump, the short one of course. When I started the car the leak increased. So, I had to drive back to my father's garage and saw it was leaking somewhere at the top flange or the terminal area.

I took my coupe and headed to a cruising that takes place today and felt something was wrong; one of the front brake was overheating. I pressed the pedal hard a few times and then it went all the way in... I drove back 20 km using the parking brake when needed...that is another store - now there are brakes on the car but it does not release all the way. I need to overhaul the master cylinder first.

Back to the fuel pump, I have read the topic on the rebuild of the long body pump as well.

I have now taken part the bottom cap, the pump body and have the motor part with the fuel discharge pipe in one piece of course. If I understood right the fuel is in the motor section so there are no seals there? The top O-ring looked fine so I believe the fuel is leaking at the terminals.

I thought the pump had been replaced because it looked so clean and had no corrosion. But, the blue paint was not in tact so the pump has been opened at least once.



The pumping capacity is OK, I have checked that earlier. The pump housing has some dirt build-up but only minimally - just as colour. I have driven approx 800 km with the car now and otherwise the pump has worked well.

Should I buy two new large O-rings and try to get also small O-rings for the terminals? I need to solder the wiring loose I guess. Of course I could order the repair kit and get the brushes as well.

Kari Pykäläinen

1971 6.3 #5581
1968 280 SE Coupé
1993 E420
1995 Tahoe 350cid

EDIT: I dismantled the motor as well, It is indeed designed to be filled with fuel. I soldered out the wiring for the terminals.








Edited by - karra on 06/27/2009 08:58:37
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karra

Finland
862 Posts

Posted - 06/29/2009 :  11:00:50  Show Profile  Reply with Quote
Does anyone rmember which way the vanes should be at the impeller? I can not tell exactly which way it was. I can try to figure out thinking of the way it pumps... I first have to see which way it rotates.

The vanes are not equal thick; the shape is a bit like a wegde. I would guess the thicker part goes towards the electric motor. I am planning to assemble the pump - I got new viton o-rings for the terminals but could not get any other o-rings locally. My dealer sent an enquiry to Classic Center because the overhaul kit seems not to be available any more. The EPC showed the part number but not possible to order by the usual way.

Kari Pykäläinen

1971 6.3 #5581
1968 280 SE Coupé
1993 E420
1995 Tahoe 350cid

EDIT: I was able to see the direction by the dirt on the center of the impeller. In the pump housing where the impeller rotates is no dirt, but over that housing, in the "pressure chamber" there was black dirt that I cleaned away with brake cleaner.

Anyhow, the thicker part of the vane is on the bottom - opposite that I was guessing first.

The viton o-rings I got are most likely too thin - I need to find ones that give better seal. The o-ring needs to be tight enough in the start already, the terminal plugs do not squeeze in so much that the o-ring expands when pressed. Also there is only one screw to hold the terminals in place and that is not enough to create the pressing on the o-rings - they need to fit tight in the beginning already.

Probably I will install NBR (nitrile rubber) o-rings because those are used in hydraulics. The shop told me viton is better for gasoline though but the right size is not available.

Edited by - karra on 06/29/2009 15:01:50
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karra

Finland
862 Posts

Posted - 06/30/2009 :  16:01:26  Show Profile  Reply with Quote
Today I visited an industrial elastomer supplier that we use when we need hoses and seals etc. at my work.

They had everything available in Viton: http://www.timcorubber.com/materials/viton.htm

So I ordered all the o-rings and for the terminals I will get both 8 x 2 and 8 x 2.5 mm sizes because the terminal plug is a bit conical (will need to see which size is right). I will make a list what is needed if the overhaul work turns out to be successful.

The sales engineer at the shop told me that in 1971 Viton was not available so the original o-rings are most likely nitrile rubber. But, gasoline today has a lot of additives and also the ethanol that is added in Scandinavia can cause a need of better elastomer quality than nitrile is. Who knows.

Kari Pykäläinen

1971 6.3 #5581
1968 280 SE Coupé
1993 E420
1995 Tahoe 350cid
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karra

Finland
862 Posts

Posted - 07/03/2009 :  15:23:33  Show Profile  Reply with Quote
I have been struggling with the pump all afternoon.

I assebmled the pump with the 8 x 2 mm o-rings for the terminals. When putting the "pressure chamber" together with the motor section I saw the 71.5 x 2.4 mm o-ring was much too thick in order to close the flanges all the way. I managed to connect the parts together by compressing the unit on a bench. The bottom cap was OK with the same size o-ring.

But, it leaked after my 10 km test drive. I assumed the leak was from the terminals because it looked that way. I replaced the o-rings with thicker 8 x 2.5 mm ones. I saw the big o-ring between the motor and ther "pressure chamber" was already deformed but still assembled all the way. Then, it leaked immediately from that flange connection. I saw the big o-ring had damaged badly; it was cut in half almost all the way.

I measured the space for the o-ring and saw it is only 0.3 mm gap, but there was approx 1.5 - 2 mm thick o-ring in place. I managed to source out a large viton o-ring having 1.7 mm thickness after working hours still. I needed to cut it and glue back to proper diameter. But, superglue does not work with viton. I found one old nitrile o-ring that I glued to correct size and tried that, but it still leaks from that flange.

Can it be that on that connection there is a gasket instead? The place is not good for an o-ring as it can slip away when pressing the flanges together. I did not find any information in my shop manual.

My dealer said the repair kit contains two larger o-rings and one smaller. Can it be like this:
-one approx 55 mm for the motor housing
-one approx 71 mm for the bottom cap
-one approx 18 mm for the shaft in the "pressure chamber"

In this case there is no seal (o-ring) between the motor and the "presure chamber" ? Maybe I can use the red engine sealant (oil & gasoline resistant) that comes in a tube. Plus a paper gasket that I can cut out.

Has anyone tried a simple in-line fuel pump, like DB Depot in Germany suggest on their website?





Kari Pykäläinen

1971 6.3 #5581
1968 280 SE Coupé
1993 E420
1995 Tahoe 350cid

Edited by - karra on 07/03/2009 16:37:38
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karra

Finland
862 Posts

Posted - 07/03/2009 :  17:53:39  Show Profile  Reply with Quote
I found out from detali.ru that the repair kit contains 3 sizes of o-rings and the brushes. This backs up the theory that the one connection is without an o-ring.



But, o-rings no. 164 and 167 are available separately, what might those be? And is this picture for the long or short pump?

Anyhow I will try to fabricate a paper gasket for that place and add some engine sealant.

Kari Pykäläinen

1971 6.3 #5581
1968 280 SE Coupé
1993 E420
1995 Tahoe 350cid
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paul-NL

Netherlands
4248 Posts

Posted - 07/03/2009 :  18:07:34  Show Profile  Reply with Quote
Hi Kari,

that pump of DB Depot looks like a 6.9 pump. I suppose it is ..

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