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  #1  
Old 09-09-2020, 11:17 AM
Proud Meep owner
 
Join Date: Jul 2017
Location: Redding California
Posts: 13
Om617 prechamber leaking.

Alright guys I've got a 1984 om617 out of a 300sd stuffed into my 1984 Jeep CJ7. I've been fighting some pre-chamber issues for a little while now and I'm not really sure what I should do next to resolve the issue.
So a few months ago I noticed inadvertently (like most people) that #2 and #3 prechambers were leaking after I had bled the injectors and fuel collected down at the pre-chambers. Okay no big deal I bought new sealing rings and slammed them in easy peasy. I thought I'd done a pretty decent job cleaning the carbon off of the pre-chambers and seal surface but apon reassembly I took my 2 leakers and turned it into 4 hooray. So it came apart again and this time I was meticulous about the cleaning. Another thing to note was the first set of pre-chamber sealing ring were Victor Rienz brand and when I was inspecting them after I pulled the pre-chambers was the quality seemed to be somewhat lacking so I bought Mercedes OEM sealing rings and the fit and finish on those were top knotch. Everything looks good I didnt see anything out of the ordinary with the pre-chambers or the head and the pre-chambers dropped in with out any coercion required. I torqued the pre-chamber collars to the required 180nm. Fired it up and it still has leakage coming from #2-#3 after a little runtime #3 seemed to seal up but #2 still leaks. I brought it up to operating temp hoping that maybe with some heat it would seal up but no love.
Has anyone run into this problem before? Any ideas on a solution to this I've run out of ideas except to do a hot re-torque? Any advise would be greatly appreciated thank you.

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  #2  
Old 09-09-2020, 01:17 PM
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Location: Long Beach,CA
Posts: 51,250
If you are speaking of a little bit of small bubbling what people think is leaks is often not leaks.
In the attached picture the orange lines show an area where there is space for fluid to accumulate.

When fluid gets into those areas and the thread area it bubbles.

What are the bubbles caused? If you feel your Fuel Injection Lines while the Engine is running you will feel the shock/vibration. So the Injector gets that shock/vibration as well as what ever shock is created by that diesel knock of combustion.
Some of it could also be heat and vapor evaporating off of the fluid.

As you likely noticed when you removed the pre-chambers carbon eventually fills in the clearances and in time that is what is going to happen to a new installation.

If there was an actually pre-chamber leak during combustion you would get some considerable velocity of the gasses out of the leak and perhaps noise.

As long as there is liquid sufficiently thin inside the crevices it is going to have those little bubbles. You can continue driving it till that liquid has either evaporated or gotten thick enough not to bubble our pick the worst one to experiment with and see if filling that area with brake cleaner causing the stuff to float out of the crevices where it can be wiped off and repeating that till there is no more bubbling.

As you repeat and wipe the stuff gets diluted to the extent the brake cleaner will evaporate and there won't be sufficient liquid to bubble.
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Om617 prechamber leaking.-prechamber-space-around-injector-2020.jpg  
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  #3  
Old 09-09-2020, 01:25 PM
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Location: Long Beach,CA
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When I worked at the Naval Shipyard we had rebuilt an old Cummins inline Generator Engine inside of the ship. It is a 6 cylinder with 3 separate cylinder heads.

Because of the marine environment steel parts got sprayed down with stuff similar to WD-40.

After assembling the Engine and it was running and tested I was called back to the ship. The Engine was experiencing that tiny bubbling between the Cylinder heads and out from under them. I explained the issue to the Chief and keep spaying the bubbling areas with stuff similar to brake cleaner until there was no bubbling and told the Chief it was fixed and never was called back.
The spray got rid of the WD-40 type stuff. No liquid no bubbles.
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Old 09-09-2020, 02:17 PM
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Join Date: Jul 2017
Location: Redding California
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Okay I never considered the pulsation from the injection system possibly causing bubbles to form. When it reached operating temp I figured most of the bubbling I was seeing on the other injectors was the soap water I was using boiling off. As far as #2 goes its different than the others it steadily creates bubbles in the soap as long as it is running. Its doesn't seem like its got a major leak just seepage. I was thinking of getting some super bubbly stuff in hopes that if there were gasses escaping from the particular cylinder it would create a large bubble instead of a bunch of tiny ones. One weird thing is #1 doesn't have any bubbling at all hot or cold even when the others seem to be boiling the water off the soapy water on 1 just seems to run off so in my eyes that was the goal for the other 4 cylinders but from the sounds of it I might be overthinking it. The engine runs great idles smooth starts no problem. I've been chasing a smoking issue with it. It hazes at idle so I've been going through the usual suspects and I think I'm suspecting injectors but just trying to narrow things down and make sure I've done the basics before I do the injectors. But thats another subject altogether. I'm planning on doing a compression test on it I just wanted to make sure I didn't have a compression leak coming from the pre chambers that might screw up the numbers.
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  #5  
Old 09-14-2020, 10:50 AM
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Join Date: Jul 2017
Location: Redding California
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Well I performed a compression check on the engine and the results were within spec although #2 did have lower compression than the rest it was still acceptable and within the 25psi variance allowed between cylinders. So Im just going to roll with it and send my injectors out to be balanced and new nozzles. Hopefully that resolves the idle haze I have so I can finally get this thing on the street. Thank you for the advice alway helpful as usual.

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