Leaking diesel from injector pump

[Mike VS]

Hello everybody, I found a slow diesel leak from the underside of my JD 5205 injector pump. There is a large size "plug" on the very bottom and is not easy to reach without taking the pump off. Is anybody aware of what this is and why it's leaking? It only leaks a few drips per hour. Picture attached after the fuel was wiped away. The plug is in line with the throttle shaft, just past it and underneath.

 

[thepumpguysc]

What’s the name plate on the pump read.??

 

[thepumpguysc]

That’s the advance plug.. it has an adjustment screw and lock nut, sealed with an oring..
Depending on WHERE it’s leaking, the big plug is sealed with 2 orings of different sizes.. and the adjuster screw has an oring behind the nut and seals on the face of the big plug.
If it’s leaking behind the nut/screw, HOLD THE ADJUSTMENT SCREW WHILE BACKING OFF THE NUT..

 

[Mike VS]

That’s the advance plug.. it has an adjustment screw and lock nut, sealed with an oring..
Depending on WHERE it’s leaking, the big plug is sealed with 2 orings of different sizes.. and the adjuster screw has an oring behind the nut and seals on the face of the big plug.
If it’s leaking behind the nut/screw, HOLD THE ADJUSTMENT SCREW WHILE BACKING OFF THE NUT..

I thought this might happen... The picture you are talking about (adjustment screw) is not where the leak is. I used that photo as a reference to where the second picture was taken. The leak is below that area, and is at the very bottom of the pump. The flying saucer looking pic is the "plug" where it is leaking from.
To be honest, the leak could be farther back than what I described. It is so hard to see even though I got it very clean. The fluid does start dripping from this plug, but maybe it's running down from elsewhere.

 

[Mike VS]

What’s the name plate on the pump read.??

Stanadyne M1DB2-335 5648 There are other numbers on the pump but hard to see.

 

[thepumpguysc]

Check this.. dry your hands and reach around the pump (from the top) to the other side of the pump, just about the area of where the side window would be.. now check your hand/fingers, are they wet.??
There’s a plug on that side of the pump that is loose from the factory.. it’s a tamper proof TORX screw..

 

[thepumpguysc]

 

[Mike VS]

View attachment 1315208

I think you got it! I just came in from re-checking towards the back of the pump, and it is coming from there. It is extremely tight to get a hand back there but I'm going back out there after reading this and going to try. My question is this; if it's not that plug, could it be the back end of the shaft that I can not see? Looking at your photo I see the round hole in a square mount w/ 4 bolt holes... Is that the back, and could it be leaking from there?

 

[thepumpguysc]

Yes, it could be from there but it’s highly unlikely..
My money is on the tamper screw.. some are 5 sided TORX tamper screws, some are 6 sided TORX..
You’ll have to get a mirror to see whatcha got..
I have used the correct bit and held it with 1 hand(finger) & tightened it with a wrench using the other hand..
U can get a little more room by loosening the hold down nuts and turning the pump in its slots..
Otherwise you’ll have to take the pump off..& you’ll need a very strong puller..to pop the gear off of the drive shaft..
(Front of the pump)

 

[Mike VS]

Yes, it could be from there but it’s highly unlikely..
My money is on the tamper screw.. some are 5 sided TORX tamper screws, some are 6 sided TORX..
You’ll have to get a mirror to see whatcha got..
I have used the correct bit and held it with 1 hand(finger) & tightened it with a wrench using the other hand..
U can get a little more room by loosening the hold down nuts and turning the pump in its slots..
Otherwise you’ll have to take the pump off..& you’ll need a very strong puller..to pop the gear off of the drive shaft..
(Front of the pump)

Yea, I'm not comfortable taking the pump off so I'll try the best I can to tighten it in place. I have a bore scope that I'm using, but it started pouring and I can't get out there right now. I'll post any revealing photos if I get them. Thank you so much!