7.3 idi injection pump leaking from advance piston.

Hello to all. I just recently picked up an 89 f350 Dually 7.3 zf5. I have fixed most of the major issues that kept it from being driveable, but I am struggling with a diesel leak.

I put uv dye in the fuel filter and found that the advance piston seal was leaking. I cut off a 1" wrench and pulled out the large hex (piston hole plug) and the small pin (manual calls this adjusting screw though mine is adjusted on the rocker arm). I replaced the o ring that goes around piston hole plug and the small lip seal that goes around shaft. It seemed to fix it at first but after running some errands I discovered that is still leaking.

It only leaks under load, not revving or idling in the driveway, hence the need for uv dye.

what should I do next?
Can I remove all of the parts of this and replace the seals while it is still in truck?

Please give me some idea how to proceed. Thank you.

I have never dug into an injection pump but I would have to wonder whether or not the leak was worth fixing since those sorts of problems seem to generally occur when the IP is close to or at the end of its useful service life.

I'll second the above advice.

Fill in the trucks specs in your sig line so we can quickly see what you've asked about.
Then
Hit the stickies and tech 101 section of the idi thread...
Welcome and got pics?!

I think the pump is original. I believe that the truck has 133k on it. It runs great, so I think it is in fine shape, but the seals are old and dry.

I have a 2 places near me that are Standyne certified rebuilders, though I am not sure if that is the way to go.

The Idea of waiting 8 weeks for one of the $1500 guys doesn't really work for me. I bought the truck to go camping and will miss out on the whole summer if I have to wait 8 weeks.

Clb said:

Fill in the trucks specs in your sig line so we can quickly see what you've asked about.
Then
Hit the stickies and tech 101 section of the idi thread...
Welcome and got pics?!

Click to expand...

I tried but can't find any signature option. I am not sure what I am doing wrong.

On the home screen, before you look for new media....

Tap your avatar, name,handle,
Poke around the listed items, look for
Account details, here you post an avatar.
Go to signature there.
Tap it.

The injection pumps have an expected service life of 100k so if you're at 133k you're on bonus time already.

DirtyWood said:

The injection pumps have an expected service life of 100k so if you're at 133k you're on bonus time already.

Click to expand...

Took the words right out of my screen!

Did you feel how well that seal fit on the pin? I assume it is leaking on the id of the seal, or is ot leaking around the od?

Black dawg said:

Did you feel how well that seal fit on the pin? I assume it is leaking on the id of the seal, or is ot leaking around the od?

Click to expand...

It was much tighter on the shaft after replacing the seal. It is leaking around the pin. The UV dye is visible around the pin. I haven't ever seen it leak, but I did clean the dye off when I changed the seal. The attached photo is after changing the seal.

DirtyWood said:

The injection pumps have an expected service life of 100k so if you're at 133k you're on bonus time already.

Click to expand...

That is a disappointing reality. 100k isn't impressive at all.

ArminTamzarian said:

That is a disappointing reality. 100k isn't impressive at all.

Click to expand...

Pumps can and do go longer but performance drops off. Since the IP is lubricated by the fuel I would guess that a pump ought to last longer with a lubricity additive and this is certainly my hope with the Opti-Lube XL I use in every tank. On my last truck with an IDI the IP developed a leak around 140k but still ran quite well.