Disco 1 leaking fuel pump possibly caused by overboost?

help just fitted a reconditioned fuel pump ( not paying over the odds for a new one) to my 300 tdi manual all's well but I seem to have an issue with fuel leaking out of the breather,( the same reason I replaced it in the first place) I asked the manufacturer and they have suggested the turbo is overboosting is this feasible and how do I cure it (I'm not chasing extra power I just want it to run nicely and not break itself or my bank balance)

I didn't know that there was a breather on an injection pump

There is.
Top rear of boost diaphragm flying saucer thing.

Golum said:

help just fitted a reconditioned fuel pump ( not paying over the odds for a new one) to my 300 tdi manual all's well but I seem to have an issue with fuel leaking out of the breather,( the same reason I replaced it in the first place) I asked the manufacturer and they have suggested the turbo is overboosting is this feasible and how do I cure it (I'm not chasing extra power I just want it to run nicely and not break itself or my bank balance)

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A photo of the pump showing where the diesel is leaking from and a bit more description would be helpful, there is not a breather on the Bosch VE injection pump body as far as I know, diesel is circulated through the pump internals to lubricate all the moving parts, there are a number of seals that can leak though.

Flossie said:

There is.
Top rear of boost diaphragm flying saucer thing.

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Top side of that is the boost pressure side of the "on boost" fuel adjustment diaphragm surely that cannot be vented otherwise it won't do what it's supposed to do.

oops yes a picture would help I suppose from the point arrowed they have said the company have said they'll replace the pump part that has failed but I need to find the cause of the overboost :| I have no idea where to start

I didn't mean 'top' in the literal sense, just a rough area on the pump.
The vent is just below the diaphragm which is on top of the pump.

Golum said:

oops yes a picture would help I suppose from the point arrowed they have said the company have said they'll replace the pump part that has failed but I need to find the cause of the overboost :| I have no idea where to start

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Yes, that's the vent I know of.

That chamber should be free of fuel.
I guess a seal that seperates the fuel side of the pump from the boost air side has failed?
Dunno...
I'd get the boost checked but I can't see it being that but happy to be corrected!
I ran 20psi once without that happening.

Flossie said:

That chamber should be free of fuel.
I guess a seal that seperates the fuel side of the pump from the boost air side has failed?
Dunno...
I'd get the boost checked but I can't see it being that but happy to be corrected!
I ran 20psi once without that happening.

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hence me asking on here as I'm at a loss the company that supplied the pump have said they will replace the part but I don't want to send it back without getting to the bottom of the problem of why that seal failed on both a recon pump and my original the turbo was on my original engine and "as far as I know" working without any issue but she was quite covered in oil and detritus by the time the swap happened

Flossie said:

That chamber should be free of fuel.
I guess a seal that seperates the fuel side of the pump from the boost air side has failed?
Dunno...
I'd get the boost checked but I can't see it being that but happy to be corrected!
I ran 20psi once without that happening.

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Plus 1 on all that, I have mates with 300tdis running vvt's doing 20psi boost and no IP issues, boost pressure only applies to the top of that diaphragm, so cannot see how that could be causing the leak.
There is a seal on the pin that protrudes into that chamber to interface with the boocst fuel cone.

Over boost cannot cause a fuel leak. Leaking seals can.

Gazbo said:

Plus 1 on all that, I have mates with 300tdis running vvt's doing 20psi boost and no IP issues, boost pressure only applies to the top of that diaphragm, so cannot see how that could be causing the leak.
There is a seal on the pin that protrudes into that chamber to interface with the boocst fuel cone.

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they seem to think the same but surely if there is an over boost problem then would it be possible to "blow" that seal out and allow fuel in???

Golum said:

they seem to think the same but surely if there is an over boost problem then would it be possible to "blow" that seal out and allow fuel in???

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If the diaphragm is not blown out then there can be no pressure effect into that chamber, and the pressure generated by the turbo is insignificant in reality compared to the capability of the seals on the fuel side.
I admit it is an unusual problem but there will be a failed seal somewhere in that boost pin chamber somewhere, also strange it has happened with two pumps.
You should check that all the fuel system piping is in place and set up as it should be.

I don't think it has happened with two pumps? Same pump reconed?
Didnt sort the leaking seal but left it in place?
Damage where the seal sits so it will never seal properly?
Crack in the pump somewhere?
Was it tested on a rig before being sent back?

Flossie said:

I don't think it has happened with two pumps? Same pump reconed?
Didnt sort the leaking seal but left it in place?
Damage where the seal sits so it will never seal properly?
Crack in the pump somewhere?
Was it tested on a rig before being sent back?

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Good point, assumed it was a replacement pump, in which case something has been missed by the "reconditioner", the "overboost" reason they gave sounds to me like a divert tactic.
In my and other opinions not a reason for a fuel leak.

now that does have me thinking they missed something now you've said that GAZBO as when I sent the pump off it was on a "one for one" and I removed the throttle bracket and unusually the "new" one didn't have the throttle bracket either although the company have told me they bench test each one for at least two hours I wonder if they missed it on the test or thought blow it he won't notice anyhow I need the vehicle for this week and next so i'll send it off when I can get my mechanic to bring over the clamp again to remove the pump

well updates the pump if on its way back to me but the manufacturer has noticed oil on top of the diaphragm should I be worried he has suggested that the turbo may be on its way out