Leaking EPIC Rotor Sensor

[The-Duke]

Hi all,

after I've been struggling with that EPIC pump's wiring and the rotor sensor gasket the bloody thing is leaking again. This time the source has been diagnosed as the sensor (7186-009-8) itself: diesel is leaking between the casing and the resin.

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This actually seems to happen to others as well, I've found some references in this forum - but unfortunately no solution yet.

I've tried to grind off a bit (1-2mm) of the resin and fill/seal it back with JB Weld - which worked for some time, but it started leaking again at an edge. I tried a replacement sensor (hard to find one!) but that leaks more than my original one. Which makes me think that maybe the pump itself is damaging the sensor. Is it correct that the rod that moves inside the sensor touches the end and has to be pushed against the spring about a millimeter or two when installing the sensor? I suppose if that rod was off by so much, the ECU would signal an error though.
How much pressure is the sensor supposed to withstand? Could a leak test with an air compressor have damaged the sensor?

Does anyone know how these sensors look like internally, i.e. where is the leak usually located? By looking at the bushing I can't see any obvious position that could leak, this seems pretty solid to me. Is the resin supposed to actually be the seal or does this just keep everything in place? Is that black ring with the allen bolt shape (or the two holes, for older models) supposed to be removable? Would removing it be of any help?

20220605_161850.jpg

Even though trying to get this done from the outside may seem futile, my next attempt would be to remove even more of the resin (which seems dangerous when you don't know what's hiding inside) and fill it again with JB Weld, or maybe something that's less viscous. Any recommendations for a resin that resists diesel fuel? I'm also considering to apply some pressure through the plate that's usually installed on the four outputs of the pump, but due to the shape of the sensor (that bump on the back) I'm not sure how this should work.

Any more hints on what might help sealing the sensor?

Cheers
Sascha

[MinorMatt]

This is not a common fault!

I have lots of the sensors (second hand) I don't remember having to push the rod down to fit though?

[The-Duke]

Thanks, Matt. So that's another indication that there's something wrong with the pump itself... I just don't understand how it can be working correctly (the van is running extremely well) and without a fault being displayed when there's such a mechanical problem... And since the pump had not been opened (just extracted once and re-mounted), I don't understand how this could happen anyway.

Yes, when mounting the sensor, a slight pressure against the pump-internal spring has to be applied to align the sensor on the surface of the pump. Which seems very odd for this kind of component, which is rotating and would probably be constantly hitting the sensor housing during operation.

Actually, even though I can't be 100% sure, I don't think it leaked from this position before it had been extracted. Back then the leak was identified to be at the lower rotor sensor (square gasket).

[The-Duke]

However, there is no sign of "wear" inside the sensor, so I suppose during operation, the rod never reaches the off-end.

Edit: Added a foto of the leaking sensor that has been JB Weld treated...

epic-sensor-leak.png

. Doesn't look like it's leaking at the base where the source could be the O-Ring.

[MinorMatt]

That sensor measures how deep the rod goes within it, the further back the rod is, the more fuel is injected (or possibly the other way around, I can't remember off hand

[The-Duke]

Anyone ever dismantled such a sensor? What does this look like internally, i.e. where does the fuel manage to escape? The bushing, is that one bored piece or is that cap fixed/sealed in any way?

[denz]

The-Duke
I had the same issue as you with the leaking sensor.
I used a dremel with a High Speed Steel Rotary Burr to get as much of the old sealant out and used JB Weld also,it worked for a while but leaked again.
Used a Dremel again to grind out the JB Weld but this time i went a bit to deep and after blowing out the grinding dust could see Copper traces or some kind of circuit. Be extra careful around the wires.
Looking for a replacement but hard to find in Australia.
I washed thoroughly with Denatured Alcohol a few times, I then used a Potting Mix (RS PRO Black Epoxy Potting Compound 50 ml) The first time i did it i must have trapped a air bubble that rose to just below the surface and blew out after a day. Ground out the weak area, reapplied some more epoxy and all has been good for the past six months.
Regarding the "O" ring gasket, from what i can gather the Original was a Flat O Ring, Thickness unknown ( Unobtainable now. )
Mine had a 0.7 mm O Ring fitted. When i reassembled i had about 0.2 of rod resistance. Still weeps slightly.
I did try a 1.5mm O Ring, I don't know if it was my imagination or not but it seemed to blow more black smoke so i went back the 0.7 O Ring.
Hope some of this helps, I am sure you will get the Change it to Bosh. Mine is Auto so i cant.
Cheers
Denis

[The-Duke]

Hi Denis. Thanks, that's the way I'll go (again) as well. After applying more JBWeld on top, fuel now comes out of the cable which I believe is impossible to seal from the outside. Next step will be to remove as much as possible of the original resin (after all of the JBWeld), in the hope to get to a point where the actual internal leak can be fixed instead of just trying to seal it from the outside.