1996 2.5di Bosch Fuel Injector Bleed Nipple Won't Close!

[Timelourd]

Weird problem - the bleed nipple won't close on my Bosch fuel injector pump. As soon as I start to turn the engine over, the hole just spews out liquid. I tried tightening it completely, and loosening it completely and nothing stops it.

I took it out and inspected it and it appears fine - clean and threads neat. There is a rubber seal which I removed and inspected, and it's also in fine condition.

Thread in the hole also appears fine.

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Anybody know the thread and thickness of this so I can get a screw for a replacement in case of emergency.

[Timelourd]

Spoke with Bosh aftermarket diesel specialist and he said a m12 x 1mm thread should match and I could replace the bleed nipple with that if it's faulty.

I'll update with results.

[Timelourd]

Looking at diagrams, it appears this is an overflow valve.

Any ideas what might be causing an overflow? I assume it would have to be a faulty injector, since injectors are the only things going between the pump and the actual engine.

[Timelourd]

Alright, so I took out the bleed nipple to check it, which drained the pump. I've since put it back in to prime the pump and blocked the nipple off with a bit of self amalgamating tape and a zip tie to keep it from leaking again.

Then the engine was dry of fuel of course, so I sat there and got the air bubbles out through the fuel filter return line, or at least tried to. The engine was originally turning over pretty well, but now it's just giving it one or two turns before calling it quits. Battery got to 12.5v so I decided it was time for a charge. Charged that up to 13v and gave the engine a few turns, and still the engine does about 2-3 turns before stopping trying. Now the battery is at 12.3 again, and I've only tried it twice.

Not sure if there's just too much air in the system and I need to keep bleeding, or if I've killed the alternator, or what is going on.

Pretty desperate at this point since my house is attached to this monstrosity, so I would greatly appreciate some advice or input.

[knobby1]

A 12.5 or 12.3v battery is still good....I suspect your starter may have given up.

Lord Knobrot

[Timelourd]

My final solution to the leaky injection pump bleed nozzle/nipple:

Welded a nut to the end of the nozzle (dirty job with MMA instead of TIG, but hey ho it works).

A bit of rubber between nut and bolt keeps the 6.5 bar of pressure from the Bosch VE pump from leaking out.

I was sure to wrap wet cloth around the threads to keep spatter from melting onto the threads, otherwise the whole thing would be scrap.

Also, it's best to only weld the outside edge of the nut unless using TIG, because you don't want flux getting inside the nozzle and potentially into the pump/injectors.

[Timelourd]

This was an insane problem to fix. And the previous solutions in the thread are all wrong.

Even though I ended up welding the nipple shut and it drove fine for a while; the diesel leak never stopped.

Then, I went and got a professional's opinion. I asked him where he thought the leak came from. He shrugged and said 'could be the front injector'.

Now, I'd already replaced it, but I must have knocked it. When I replaced it the leak stopped, and from what I now understand, the hole in the bleed nipple is a specific size to allow fuel to leak out when fuel pressure in the engine is too high and the fuel return hoses can't handle the extra load. Since the bad injector wasn't taking in any fuel, it was coming out the bleed nipple, which I then welded shut... lol... ffs...

Well, all part of the learning experience. At least now I've fixed the fuel leak from all angles.