O-rings fuel pump

[lollo66]

My fuel pump externally fuel wet and dirty.

I removed and disassembled the pump, the problem is the external O-ring seal (part 6 in picture).

I think the O-rings (3 and 6) are viton made but I do not know the exact dimensions; can you help me to find the correct reference of these rings ?

[Hubertus]

Hello,
buy the tings by Manfred Graf.

[Manfred]

Hello Lorenzo,
all fuel-pumps i know which where leaking had the same problem.
It leaks between the plastic top and the aluminium chasis.

pump.jpg (36.92 KiB) 7386-mal betrachtet

To repair this you had to clean the surface of the plastic top with alcohol or fuel, i use therefore cotton-sticks (q-tips)
After this i use epoxy (i.e. UHU plus), mix it and put a little bit around the alu chasis at the plastic surface

epoxy.jpg (36.98 KiB) 7386-mal betrachtet

Next i use my hot air gun, normaly used for smd unsoldering, switch it to lowest temperature and air preassure, heat the epoxy until it gets fluid and blow it with the air stream over the surface and into the gap between the alu chasis and the plastic.

hot-air-2.jpg (57.15 KiB) 7386-mal betrachtet

hot-air-1.jpg (29.22 KiB) 7386-mal betrachtet

After its hardened it will look like this and will be leak-proof for years. I did this 8 years ago at the org. fuel pump of the 1600i engine in my old convertible. Its still ok.

pump-sealed.jpg (46.46 KiB) 7386-mal betrachtet

I never had leaking o-rings. But if you disassemble your fuel pump and unmount the o-rings, they will get larger and you couldn't use them for now. Wait 24 hours and they will fit again.
Years ago i bougth some o-rings. At the moment i only found the larger one. Somewhere should be the same amount of the smaller ones.........

o-rings.jpg (38.67 KiB) 7386-mal betrachtet

I never tested them. But if you like to it. Shippment to Italy will be 1,50 €. You can spent me a beer when we will meet us sometimes. In this case please mail me the adress.

And please, don't spam me with e-mails, 20 of them are 19 to much. If i get enough time to write a answer, i will do it.

cheers Manfred

[lollo66]

Manfred , thanks for all instructions .

I'm sure my fuel pump leakt between the black plastic cover and black plastic body , for this i made did these tests

fuel pump preparation for air pressure test

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low pressure adjustment of the air compressor......

100_3516.JPG (124.93 KiB) 7344-mal betrachtet

soap and water mixture preparation

100_3517.JPG (109.18 KiB) 7344-mal betrachtet

brush the mixture between the plastic and the aluminum chasis top of electric pump

100_3520.JPG (167.56 KiB) 7344-mal betrachtet

100_3521.JPG (149.18 KiB) 7344-mal betrachtet

small air bubble .... small fuel leak

100_3522.JPG (133.86 KiB) 7344-mal betrachtet

here exactly

100_3524.JPG (139.35 KiB) 7344-mal betrachtet

brush the mixture between black cover pump and aluminum chasis of electric pump, under this area there is a small O-ring

100_3525.JPG (144.54 KiB) 7344-mal betrachtet

to be continued...........

[lollo66]

perfect no bubble ........ no fuel leak

100_3526.JPG (119.94 KiB) 7340-mal betrachtet

100_3528.JPG (137.75 KiB) 7340-mal betrachtet

Now brush between the black body pump and black cover pump, between this is the big O-ring.
This side is perfect

100_3529.JPG (138.99 KiB) 7340-mal betrachtet

On this side a big bubble ..... fuel leak

100_3532.JPG (208.37 KiB) 7340-mal betrachtet

Yet another bubble ....... yet another fuel leak

100_3533.JPG (197.69 KiB) 7340-mal betrachtet

Other sides are perfects

100_3534.JPG (135.71 KiB) 7340-mal betrachtet

100_3535.JPG (154.04 KiB) 7340-mal betrachtet

To be continued

[lollo66]

I highlight the leaks points

100_3538.JPG (140.38 KiB) 7340-mal betrachtet

I unscrew the cover screws , lift the cover and…….. surprise! the big O-ring appears damaged

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100_3542.JPG (85.09 KiB) 7340-mal betrachtet

the small O-ring is perfect

100_3545.JPG (120.9 KiB) 7340-mal betrachtet

I now have samples of the O-Rings , I will try in the local shops for the new parts and then give you the news .

greetings all

[Manfred]

Hello Lorenzo,
as far as i can see you did not mount the pump in the wrigth order.
First the pump, then the filter over the pump, then o-ring over the pump
Otherwise the pum looks about 7-10mm to much outside and the o-ring won't get pressed at the lower side against the filter's upper side.

Yours

lorenzo-100_3521.JPG (108.51 KiB) 7339-mal betrachtet

Myn

pump-sealed-5.jpg (47.37 KiB) 7339-mal betrachtet

Wrong mounting order

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2-IMG_6469.JPG (25.18 KiB) 7339-mal betrachtet

Right order

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4-IMG_6471.JPG (22.82 KiB) 7339-mal betrachtet

I allways use some oil for mounting the rings. Also inside the plastic cover and at the pump.
To shove the cover over the large ring, twist the cover a bit in one direction.
The damage of your large o-ring looks to me like a mounting failure. It has got pressed between the lower and upper cover.

[lollo66]

Manfred,

you're right!
when I reassembled the fuel pump I was wrong the position of the electric pump! but this is not a problem for possible fuel leaks in this area.

I think the fuel pump has never been disassembled; then for the big O-ring a possible error of assembly at the Pierburg factory?....is possible a non-compliant O-ring?

[Manfred]

Manfred,
I think the fuel pump has never been disassembled; then for the big O-ring a possible error of assembly at the Pierburg factory?....is possible a non-compliant O-ring?

I believe we never will get an answer therefore.

But allways keep in mind, that air is about 700 times thinner than liquid. So not all leaks found with air are also leak with gasoline.