Over the last few days my OM617.952 has developed a nailing...at least I believe that's what it is. The sound is quite like what a gas engine makes if a spark plug wire is off. Not a big deal, but annoying.

So I had a fresh set of popped and tested injectors on the shelf so decided to install them in and see what difference, if any, it made. While taking out the injectors I noted that #3 had a considerable amount of soot in the injector hole, so much so that the bottom threads in the prechamber were filled smooth.

After installing the fresh injectors the engine runs quite a bit smoother.

But after a quick test drive, I noted that there were bubbles coming out from around the prechamber lock ring. Normally, I wouldn't even notice this but since the head was still quite wet with diesel from priming it was obvious. Here's a video -

http://youtu.be/QDlqIWiEask

The question is can I try to tighten the prechamber lock ring and maybe get lucky or do I need to pull it and the prechamber to replace the seal? And the accompanying question is if it's not leaking don't touch it, or should I do all of them because the rest are probably ready to start leaking too?

I'm guessing #3 was the source of my nailing but I won't know until I try pop testing the set to see what I've got. I've got close to 70k miles on the injectors that I know of and who knows how long they've been in there before that...maybe lots.

Eventually I'll get a new set popped and ready for the next swap, but I don't have any fresh diesel handy and since I just fueled up yesterday, it will be a bit.

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

You are supposed to replace those sealing rings if you take them out. But i put used ones in temp with no problems. I had one loose and bubbling like that and cranked it down

Paul-
I can send you relevant tools on loan if you need them. I have the collar tool (more elegant than a chisel) and the prechamber puller adapter (you provide your own slide puller). Although knowing you, you probably have that taken care of. Aside: We met at a get-together in Lompoc a few years ago.

__________________
1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).

Thanks for the offer. Actually I don't have the tools...yet, but have been researching them today and believe that I can fabricate them pretty easily. But if I get stuck you can be sure I'll be in touch. Hopefully ROLLGUY will get another cruise organized again this year.

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

Hey im in lompoc.

If you split an injector in half it threads in. I welded a nut on for a slide hammer.

That's very interesting - I was planning on going with a crank remover but I may go this route.

Thanks for the tip.

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

I try to avoid buying tools when possible, but the collar tool was beyond my skills to manufacture. I bought Kent's from WA, which worked fine (see his website). It locks into the collar slots using the prechamber threads, which is critical to success. If you just try to use your own strength to hold the tool against the collar, I doubt it would work. It is a lot of force being applied to a small area.

Kent also sells a prechamber puller, but that is a bit of a joke for his price. If you buy the prechamber collar nut tool, you can just use part of it again as the puller. For simplicity, I even bought his yellow puller via another source (Wilmar dent puller, $27). Or clearly Lucas's suggestion is a good one. Good luck.

To clarify your "crank remover" comment for newer readers, it happens that older shimano bicycle cranks use the same thread diameter and pitch where they attach to the bottom bracket. It is a relatively rare size, so some people use the Shimano or Park Tool bicycle crank remover tool to manufacture a prechamber puller. Sorry if that is old news for everyone, but I thought it deserved some clarification.

__________________
1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).

If you remove one chamber and feel like you want more power from the engine and can remove all the prechambers check out this thread about increasing the hole size.

Not too proper. And kinda wasteful unless you have a broken one. I cut it some too.

Spilled fuel around the pre-chamber will appear to boil and bubble from the engine vibration. No leak needed.

Noise: all that carbon inside the pre-chamber can dramatically change the combustion noise for the worse, even though the injector and pre-chamber are fine.

Clean off the spilled fuel, drive the car hard, noise will go away.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

Agree that spilled diesel fuel on pre chamber threads can boil and appear as combustion leak.

mach4, does the diesel bubble when the engine is cold? If so, then there maybe a combustion leak there. Another trick to spot leaks is slather it with shaving cream and look for bubbling.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Interesting! Have you tested this and observed different combustion noise with different amounts of carbon? I'd love to hear a recording of the differences.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I read about boiling diesel resembling leaks, so with the engine cold I put some engine oil on the base of the injectors and observed bubbles, so it's definitely leaking, though the bubbles are not nearly as pronounced as the diesel.

I've already swapped in a different set of popped and balanced injectors so the nailing issue is solved. I'll test the injectors I pulled out shortly and see what that shows.

The curent plan is to try to build a prechamber collar tool and try tightening the collar on #3 - after all, the self-appointed MB guru (an expert in his own mind) in the Pacific Northwest, states that many times a combusion leak can be fixed by just tightening the collar. It's worth the effort to give it a try. Worst case is it still leaks and I've got to replace the seals.

I need a project anyway...

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

That should work. Did for me. But i replaced the ring later.

When mine bubbled the collar was finger loose.

Cant remember the specs but with my torque wrench it was like 1300-1500 in/lbs. I had to get a buddy to help me out. Lol.

The machine shop said he just "cranks them down."

Its often argued, but its standard maintance to pull them and clean them.

On the 617.952 The Injector screws into the Prechamber Retaining Ring and The Ring screws into the Cylinder Head so you can not slide hammer it out.
The Prechamber has different threads for the puller that you would use the Slide Hammer on.

The threads inside of the Prechamber are M22-1.0 for the Puller.

The threads on the Injector and the inside of the Prechamber Retaining Ring are
M24-2.0

I am not 100% sure but I believe US made Slide Hammers have 5/8"-18 threads on them. That is what the Autozone Rental Slide Hammer would have if it has SAE Threads.

__________________
84 300D, 82 Volvo 244Gl Diesel