ZAAR

Hey Guys ,


Thought it was time to get some opinions.
So I have this injection leak that's shooting past the debris o-ring on the injector body and hold down nut.
9mm injectors non I/C style.
Just did the head about a few months and still cant get this thing to stop I've tried cleaning the bore again after the machine shop did,
checking the injector bodies and even re-torqueing the nuts and setting thing back in place. I think there is a variance in the thickness of washer used in the bore as I did not use a Cummins copper sealing washer at the base of injector instead I used an AG supplier item. All suggestions appreciated.







Thanks.
ZARR

kensmachine

fuel or exhaust I Can't tell by the pictures

ZAAR

Fuel if you look at the first picture right at the injector base you can see the fuel soaked area. and down from there.

thrashingcows

Have you tried torquing the nut down to 55ftlbs? I know the spec is 45, but you can go to 55 with no problems.

ZAAR

Yes I have cranked down on them past spec'd torque.
Which I thought was my initial problem I am completely and utterly lost on this one.

j_martin

Have you replaced the injector?

u2slow

The surfaces that mate with the copper washer need to be clean and smooth. No uneven carbon residue. If there is any doubt that the washer isn't soft enough to seal, anneal it by heating red hot and quenching it in water. (opposite properties to steel that way). A little bit of hi temp antiseize may help the seal, and the injector shouldn't get stuck over time.

This is how we deal with our 1950's marine engines at work... I can't see any reason this approach won't work on a little 6BT.

j_martin

The copper seal keeps combustion gasses in the cylinder. It has nothing to do at all with keeping fuel oil in the injector. There is a threaded joint in the injector above the copper gasket and below the hold down nut that can leak. If it does, it comes out around the nut or past the dust seal.

kensmachine

Its most likely coming somewhere on the Injector one of 2 things the nuts loose or cracked with a cracked you can't torque the nut and it will leak or the main injector body has something wrong like crack or hole in the main body seen both things when I worked in a fuel Inj shop ken

ZAAR

Thanks for the information guys, j Martin I have not replaced the injectors, and it does seem as if there is a pressurized hiss coming from 1 of the injectors. I think to rule out all issues I will remove the injectors and get them rebuilt its become too excessive of a leak and noise, and I honestly think you guys are right on the money the dust seal are blown out from around the injector and nut area and the hold down nut is filled with fuel.

cougar

A trick to help pinpoint the source. Use some carb cleaner to thoroughly clean the area and make sure it is good and dry. Dust the area with talc. Start then stop the engine. The talc will wick up the fuel at the source and show you exactly where it is coming form. Found some cracks that way.

j_martin

You don't have to overhaul it to fix a leak. Buy 1 or 2 injectors and throw them in. Even if they don't exactly match what you have, (injectors get a bit bigger with age) it'll probably be so close you can't tell.

The hiss is probably the copper washer. Wire brush the hole and replace the seal (washer)

u2slow

My bad. I thought he was blowing back fuel and combustion gasses past the copper washer.

kensmachine

if it where mine I would take the injector out and try to tighten the nut first look to see if it's cracked first it's been a long time but I think there 15 or 16 MM on the nut just use an end wrench and gave it a good pull ken

jimbo486

If the injectors are original, I wouldn't hesitate at all to have them rebuilt. It should only cost you a few hundred dollars to have a local fuel injection shop go through them.