MEP-803 compression bypass by injectors

[Sidis8]

2010 803, around 250 hrs. I was replacing the fuel return lines because they were leaking. After replacing, had some diesel left over on the head by the injectors. When running it, noticed small bubbles forming around the injector.

Reached out to a few guys on here, followed their advice.
1. cleaned the injector bores
2. New oem copper washers
3. Torqued down to manual specs


Compression is still getting by the injectors somehow. not loosing any power and there’s no visible soot around

I got a second 803 and checked on that one, it does not do it. Poured soap water solution on it and it just sits there.

I’ll attach a few pics. The first two are the one that’s leaking, the white blurs in the picture are the soapy water shooting out. The 3rd is the other 803. I would attach a video but can’t figure that out lol.


u guys ever see this?

 

[Ray70]

Yes, had that same issue a few times. Assuming you had everything clean and did not have an extra washer stuck down in the hole... My advise is to take it apart again, make sure the hole, the washer and the injector are all clean.
Reassemble and tighten the bolt.
Take a hammer and something steel that is flat on the end and sharply hit down on the wings of the clamp a few times, then recheck the bolt and retighten if necessary.
Start it up and check again.
Sometimes taping it down while the clamp is tight can help the copper washer conform to whatever is preventing a good seal.
The only other thing is depending on what you used for washers, I assume they are dead soft copper, but if in doubt, heat them cherry red and allow to air cool slowly to anneal them.

 

[Light in the Dark]

Definitely make sure there isnt a second washer in there, and as Ray said... you may just need to anneal them. Only so many things could be causing this. You did confirm there are no hairline cracks in the injectors anywhere?

 

[Sidis8]

Double checked there’s only one washer in the bore.
Then tried the annealing thing.
Injectors look good, took one apart and didn’t see anything.
Tapped the wings down with a piece of metal and a hammer also.
Still no luck, leaking like before.


As a last resort, tried one of the injectors and washers from the other 803, and doing the same thing.

it’s gotta be something with the head ? Like a crack in the bore somewhere ?

 

[Ray70]

Humm.... have you been able to get a good close-up look down in the hole to see if you can see any pitting, crap or a crack?
A crack is unlikely, I'd be betting more on something preventing the washer from sitting flat.
Either a ridge, gouge or a piece of crap stuck down in there.

 

[2Pbfeet]

@Sidis8 I tend to agree with the other folks that debris is a more likely cause than a crack. Brake cleaner, and brushes help.

I would say that I have found more than a few extra copper washers lurking at the bottom of injector ports pretending to be part of the head. I sometimes think some folks subscribe to the "one is good, two is better" on the copper washers. (Not!) However, due to manufacturing tolerances, sometimes a slightly thicker washer may be in order.

It sounds like you are doing the right things. I would be tempted to go through the clean/check/clean cycle a few more times. Do you have a borescope that you could have a closeup look down there?

All the best,

2Pbfeet

 

[Sidis8]

Thank you to every one for the help. Got it all sorted out.

found a few old threads about using a counter bore for injector seats for old diesel

Tried it, then annealed the washers. Works great.

No more leaking blow by.

now just gotta find the next problem to fix lol.

 

[2Pbfeet]

@Sidis8 congratulations! Thanks for the follow up.