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+--- Thread: Pre Chamber discussion (/showthread.php?tid=8487)
Pre Chamber discussion - TE27Levin - 02-19-2022
Hello gang, I would like to discuss the the possibilities of pre-chamber servicing and rebuilding and diagnosing potential future problems of Pre-chambers.
I recently purchased a used cylinder head that ate a couple of chambers. It was sold as is, having four remaining good chambers still intact.
I have the Mercedes pre-chamber slide hammer tool and I used it to extract the remaining good ones as well as the damaged chambers.
The damaged chambers were mushroomed from getting hammered in the combustion chamber so I had to use a die grinder to remove the flared out portions as well as some of the burs. The head is pretty mucked but I did whatever I could to not make any further indentations on the head. All eight valves are bent in the corresponding cylinder one and two.
I gotta say, the Mercedes slide hammer tool, is totally inadequate for the job. It requires a tremendous amount of force to remove these things. Well at least with the cylinder head off the vehicle.
The method I ended up using required that the head was stood up on end, and pivoting it away from me whilst using the slide hammer bit with both hands. I removed all six but my hands are rekt.. Even with gloves.
That said, when I removed them. It became evident that the good ones weren't that far behind the damaged ones.
The so called "Ball, fuel vaporizer?/atomizer" is actually a shaft that round at the center with the one side facing the injector and concave towards the downward ports on the Pre-chamber. The shaft is pressed and staked in place with one solid line. And I believe turned or polished to the shape of the chamber body.
Well.... only when the pressure of installation was taken away (that is removing them from the cylinder head Pre-chamber bore.) Small cracks were seen on the opposite side of the staked end. They were actually in two pieces at this point. The other end, that we will refer to as the pin side of the vaporizer. Had the cracked side just off where the "ball" starts to taper down to the pin end.
You can hear them jingle when shaken. So I took them to the vice with a rag on end and I managed to tap out the pieces from the pin side and fire the rest out of the staked side. Which didn't take much effort by the way. Out they came in two pieces.
I got one good chamber out of the four. The bodies however are in excellent shape. So brings me to this..
What sort of material are these Pre-chamber (vaporizer balls) constructed of? They are magnetic is what I found. But could they possibly be manufactured and replaced before the pre-chamber loses its end and destroys your engine?
EDIT: just want to add, I am not blaming the seller for this, it would be incredibly hard to tell to judge these chambers in head.
Pictures to follow.
RE: Pre Chamber discussion - TE27Levin - 02-19-2022
Also to note, the bodies of these pre-chambers with the broken "balls" look perfect.
RE: Pre Chamber discussion - barrote - 02-21-2022
Hy,
What u have found its pretty common, in long mileage engines.
Actually no diff from a other types of pre chamber , like VW.
Back in day there were lots of options to replace the balls, even larger smaller and so on, but as this engines were retired after market diesel parts specialist stopped offering this replacements.
But i guess there some available yet. Got to search.
Usually replacing the ball shaft give u another lifetime on those,make sure the holes are clean and with right diameter.
Regards
RE: Pre Chamber discussion - TE27Levin - 02-21-2022
(02-21-2022, 02:52 AM)barrote Hy,
What u have found its pretty common, in long mileage engines.
Actually no diff from a other types of pre chamber , like VW.
Back in day there were lots of options to replace the balls, even larger smaller and so on, but as this engines were retired after market diesel parts specialist stopped offering this replacements.
But i guess there some available yet. Got to search.
Usually replacing the ball shaft give u another lifetime on those,make sure the holes are clean and with right diameter.
Regards
So replacements were a thing? Very cool. It is a pretty uncommon engine in North America. I don't think the market even existed for the balls...
Anyone have any information on the materials used?
RE: Pre Chamber discussion - TE27Levin - 02-23-2022
Update:
Well I sent these things off, the material we are discussing to be used will be Inconel HX.. They are going to do the drawings and prototyping. We will see where this goes fellas.
RE: Pre Chamber discussion - barrote - 02-24-2022
Last time i checked our the suplier did not had any in stock.
Since we just needed 2 we searched the wreck bin and found 2 ball's in good shape. Costumer did not came back .
I also remember to read somewhere about checking precup condition every X Miles... i just don't remember for wich enginr was...
I know that they fail in the 4 valve engine more often than in 2 valve . Never heard of a fail in 616/7.
I'll ask the suplier again.
RE: Pre Chamber discussion - TE27Levin - 02-26-2022
(02-24-2022, 03:28 AM)barrote Last time i checked our the suplier did not had any in stock.
Since we just needed 2 we searched the wreck bin and found 2 ball's in good shape. Costumer did not came back .
I also remember to read somewhere about checking precup condition every X Miles... i just don't remember for wich enginr was...
I know that they fail in the 4 valve engine more often than in 2 valve . Never heard of a fail in 616/7.
I'll ask the suplier again.
Very interesting. My engine has relatively low kilometers. I am under 200 000. But it was run with poor injectors in its previous life. I did put in, injectors with new nozzles and pop tested to specification.. I just want to have some chambers ready to go in case I happen to have a bad one or two when I pull everything apart to check them. It does have a lot of weird nailing from time to time. I noticed switching to shell V-power diesel + wurth diesel fuel additive made it a lot smoother. Which could be just masking the problem.. Inconel HX is going to be pricey perhaps it is overkill? Not sure how it handles vibration...
RE: Pre Chamber discussion - barrote - 02-28-2022
In case u have nailing u have to check it out...
I know cases where the shrapnel goes down the tip and destroy the cylinder.
Good luck.
RE: Pre Chamber discussion - TE27Levin - 03-01-2022
(02-28-2022, 03:04 AM)barrote In case u have nailing u have to check it out...
I know cases where the shrapnel goes down the tip and destroy the cylinder.
Good luck.
That is my worry sir!
Well I just heard back from the machinist. Inconel is going to be pretty difficult for them to machine such small pieces of the stuff.
Anyone have any ideas for a material to use that is equivalent or superior to the stock stuff but is a tad bit easier to machine?
RE: Pre Chamber discussion - Austincarnut - 03-01-2022
(03-01-2022, 11:32 AM)Try unobtainium.TE27Levin(02-28-2022, 03:04 AM)barrote In case u have nailing u have to check it out...
I know cases where the shrapnel goes down the tip and destroy the cylinder.
Good luck.
That is my worry sir!
Well I just heard back from the machinist. Inconel is going to be pretty difficult for them to machine such small pieces of the stuff.
Anyone have any ideas for a material to use that is equivalent or superior to the stock stuff but is a tad bit easier to machine?
RE: Pre Chamber discussion - barrote - 03-03-2022
Mb sells precups !!! They're expensive but so are those fancy solutions...
Usually junk yards have solutions...
If u're in dificult i can send u some cups...
RE: Pre Chamber discussion - TE27Levin - 03-03-2022
(03-03-2022, 06:29 AM)barrote Mb sells precups !!! They're expensive but so are those fancy solutions...
Usually junk yards have solutions...
If u're in dificult i can send u some cups...
Well I am looking for a sustainable solution Mr... I have the Cad drawings now. Just need a material to select then I will pull the trigger to have them done.
What metal to use?? I am no metallurgist. But I will probably tell the machinist to put a broken precup to the grinder to see what colour the sparks are and then go from there... Well not exactly.. Hehe.
RE: Pre Chamber discussion - barrote - 03-05-2022
Hum hum , cad hein !!!
What ever material they used was forged.
But i can tell u that those are made of some sort inconell alloy.
So as the cups wich are chromolly, and the tips are diamond hard... but by heat treating...
Good luck.
RE: Pre Chamber discussion - TE27Levin - 03-06-2022
Perhaps there is some sort of inconel alloy that is magnetic as a magnet is attracted to these... I am thinking they are a lot less exotic than inconel. Just looking for a proper material to use. ..
Edit:
And also to ad. What are the differences in the Pre-chambers with part numbers 606 010 02 52 and 606 010 04 52 ?
RE: Pre Chamber discussion - barrote - 03-07-2022
At least hole size.
02 in N/A
Usually id by number 04 or 06 in the cup neck.
RE: Pre Chamber discussion - TE27Levin - 03-08-2022
Well I also asked if Nimonic 80A would be possible, and my machinist said any nickle alloy of a part that small would be too difficult to machine... The rod is also $1000 CAD a meter... 303 stainless was suggested. But I am worried about that material cracking due to vibration and also its heat rating would not be hot enough.
I am not an engineer or metallurgist clearly. Any one have any ideas?
RE: Pre Chamber discussion - TE27Levin - 04-01-2022
Well there they are. Looks like they fit. Went with 17-4
RE: Pre Chamber discussion - vica153 - 04-03-2022
Looks good. Now just need to test them out!
We are probably over thinking the material. Between the contact with the prechamber body and constantly being sprayed with fuel I think that little part isnt getting terribly hot.
RE: Pre Chamber discussion - nastala - 05-10-2022
(04-03-2022, 02:14 PM)vica153 Looks good. Now just need to test them out!
We are probably over thinking the material. Between the contact with the prechamber body and constantly being sprayed with fuel I think that little part isnt getting terribly hot.
The om617a prechambers were made from nimonic 80a because they hit 900C on the inside. (pic from om617a sae paper)
![[Image: om617aprechamber.jpg]](https://i.ibb.co/k5Qrg8v/om617aprechamber.jpg)
RE: Pre Chamber discussion - TE27Levin - 08-29-2022
Well time for an update!!
I took the time to yank my injectors and pop test them. My firrad sd314s were all popping too early if they were popping at all. They were more like "garden hosing". I cleaned them and set the pressures all higher. But before I put them in. I inspected two pre chambers that had the worst injector performance as measured with my pop tester.
There was cylinder five and number one. Cylinder number five had a heat shield that had a hole burned in it and it blasted carbon all the way up the circumference of the nozzle body. Just to remove the nozzle, I had to use pieces of plastic to press on the tip and progressively add more plastic to press against it as I screwed in the vice. It took some buggering around but I got it out.
I used my mercedes pre chamber slide hammer tool to remove number 5 chamber first. The tip of the pre chamber was pink from heat and had some pitting. It looked like a stone. I popped the chamber ball out and it looked fine. I then removed number one. I cleaned it up and tossed it into number five as it was near perfect.
Cylinder one got the prototype prechamber ball in 17-10 stainless. I zipped everything back together. Changed the fuel filter and filled it with diesel purge. Fired it up and it ran awesome because of the purge but was noticeably quieter and ran way nicer after the purge cycled into the tank.
The next day I drove it to the next town and back for a good test. Had a small leak on a pump fitting for number one. Cranked that tighter than i drove it 600 km.
I was noticing the longer I drove it. The more nailing returned. Especially at 2200-3400 rpm in low boost partial throttle.
So I decided to order proper sd310 nozzles as per Barrote's instruction.
I ordered them from diesel truck parts www.dtp-motoreile.de out of Schwarzenbek Germany. Not bozzios but hey they are made in Germany. So why not? They showed up in less than a week along with the shims. Oh they got all of the sizes.
So I took the injectors out again. And re checked them. They were not the same as I put them in on three out of six. So I wrote down the numbers and set up the new nozzles. All as close to 150 bar as I could get. Installed them and such a huge difference. I checked my timing with a piezo pick up and I was at 10 degrees btdc. Seemed to boost early and was quiet so I ran with it on a 1200 km trip.
It had less get up and go but it was decent on fuel.. So I decided to try my luck and advanced it to 16.5 btdc. It ran terrible and smoked fierce black out of the hole and insane turbo lag. I am now at 12.5 btdc but I may go back to ten.
So in closing, check your injectors and your chambers will remain happy. My proto type is working out so far but it is nice to know I have a supply of pre chamber balls if I need them.