Engine running rough after injector cleaning

[sv_isara]

Hey all, so in a fit of madness (and because i have persistent white smoke and a slightly lumpy idle when cold), I removed all 4 injectors from my yanmar 4JH2E and cleaned them - just soaked in injector cleaner and wiped off carbon.

Then here's what happened: I reinstalled. Engine ran lumpy with cylinder 4 leaking diesel (rear cylinder). I removed and reinstalled the injector. No leak. Ran quite smooth for maybe 30 seconds, and then very very lumpy, and maybe knocking. It actually died when left at idle. Still smoke, maybe even moreso.

Now, I didn't have new copper orings which are on the way from ebay (who knows how long to ship). What would be my next steps here? Take the >$1k plunge for new injectors? Get a shop to rebuild them? Run the engine longer? I'm trying to leave in a few weeks...

Thanks for any help.

[GreenWave]

I have heard that new orings are critical. Of course torque values too. Report back after placing new rings

[sv_isara]

it's hard to hear the potential knocking and unevenness in this recording.

https://youtu.be/fuP630Ho32k?si=t0ogDv9aIGEJ-TGw

Video notes:

starts up fine, idles initially ok.

Then I rev up to 1200 or so, the RPMs are wavering a bit.

Then I rev up higher, I can feel/hear the RPMs vary with small dips or unevenness

Then I go back to idle and it stalls

[s/v Jedi]

You can make the copper rings good as new, just heat them by holding in a flame until red hot then drop in water. This is how copper is annealed.

[sv_isara]

FALSE ALARM!



Fuel filters were turned off!

[cjheath]

SV Jedi, interesting.. i thought the quenching immediately after heating would not anneal the copper? I was under the impression that the copper rings would need to cool slowly but my background is electricial; I'm not a metals/materials guy. I'm certaily open to some education/learning here from someone qualified to comment.

[skipperpete]

Originally Posted by sv_isara

FALSE ALARM!







Fuel filters were turned off!

Really happy that you found the problem.
Not sure about the “copper orings”that you mentioned, the usual nozzle to cylinder head washers on 4JH and 4LH engines aren’t copper and fit over the heat protector sleeve. Older washers only fitted the one way on the sleeve but the more recent ones seem to fit either way and require no intervention other than perhaps a light polish with 600 wet or dry paper on a flat surface. Its important to record which cylinders have the washers and sleeves if they stay behind when the injectors are removed ….to avoid putting a washer and sleeve into an occupied injector socket.

[s/v Jedi]

Originally Posted by cjheath

SV Jedi, interesting.. i thought the quenching immediately after heating would not anneal the copper? I was under the impression that the copper rings would need to cool slowly but my background is electricial; I'm not a metals/materials guy. I'm certaily open to some education/learning here from someone qualified to comment.

I think you have ferrous metals in mind. For copper annealing, you quench it in water

[Jim Cate]

^^^^^

Nick, I think that you will find that copper is unusual in that one can anneal it either way: quench or slow cool. I've done it for years by sooting up the item , heating until the soot burns off and then slow cooling as instructed by an older machinist. I was surprised to find that I could get similar results by quenching which iss much faster.

Jim

[Wotname]

Jim is correct. Copper can be annealed with quenching or with slow cooling. I have used both and could never tell any difference in the resulting 'softness'. Obviously quenching is quicker and requires less cleaning.

FWIW - About 50 years old, an old retiring sheet metal instructor advised us that slow cooling resulted in slightly more malleable copper. I dunno if he was correct.

[s/v Jedi]

Originally Posted by Jim Cate

^^^^^

Nick, I think that you will find that copper is unusual in that one can anneal it either way: quench or slow cool. I've done it for years by sooting up the item , heating until the soot burns off and then slow cooling as instructed by an older machinist. I was surprised to find that I could get similar results by quenching which iss much faster.

Jim

Originally Posted by Wotname

Jim is correct. Copper can be annealed with quenching or with slow cooling. I have used both and could never tell any difference in the resulting 'softness'. Obviously quenching is quicker and requires less cleaning.

FWIW - About 50 years old, an old retiring sheet metal instructor advised us that slow cooling resulted in slightly more malleable copper. I dunno if he was correct.

Your experiments show the results but every source one can find says to quench it in water. I guess you should send your results to someone (?) to update the instructions, especially if it has superior results!

[Wotname]

Originally Posted by s/v Jedi

Your experiments show the results but every source one can find says to quench it in water. I guess you should send your results to someone (?) to update the instructions, especially if it has superior results!

Lots of stuff on the 'net is wrong and lots of stuff passed on by old machinists was also wrong but no need to correct the record elsewhere now the truth has been revealed on CF. AI will be all over within a few days!

The bigger issue was the old machinists didn't ever get a big audience while the stuff (right or wrong) on the 'net travels all around the universe in a matter of hours!

Nevertheless I did find some interesting (?) stuff about hardening copper. One guy from the University of Washington states that quenching at rates above 10 million degrees per second will harden copper. See https://www.materialseducation.org/e..._of_Copper.pdf

This one from the gov (so it must be right) is historically interesting https://www.govinfo.gov/content/pkg/...e771dfed3a.pdf

And this guy was issued a patent for a lost way of hardening copper by quenching but I suspect his process made (unintentionally) a copper alloy. https://patents.google.com/patent/US1359810A/en#

[Jim Cate]

Originally Posted by s/v Jedi

Your experiments show the results but every source one can find says to quench it in water. I guess you should send your results to someone (?) to update the instructions, especially if it has superior results!

Hmmm... one of the first citations I found was the following article:

https://mellowpine.com/blog/copper-annealing/

and within this lengthy treatise the following summary is quoted:

"Generally, the slower the cooling rate, the better the ductility of the workpiece.Therefore, quenching of the copper workpiece after annealing is not recommended for applications that require extensive cold working of the workpiece."

Seems at odds with your claim and to support the process that Wottie and I have used. Guess we don't really need to offer the experts our advice after all.

Jim

[jamhass]

The bit Jim quoted says a lot.

"extensive cold working" is for protracted forming operations. For example, forming a copper goblet on a lathe from a flat sheet. every bit of the copper gets manipulated many times.

However, our (injector) applications really only need the copper to be soft and malleable once, on initial (properly done) assembly. Yeah, a few caveats there, but even then, re-annealing is possible.

So, IMHO, go ahead and quench, especially if in any hurry.

[Jim Cate]

Originally Posted by jamhass

The bit Jim quoted says a lot.

"extensive cold working" is for protracted forming operations. For example, forming a copper goblet on a lathe from a flat sheet. every bit of the copper gets manipulated many times.

However, our (injector) applications really only need the copper to be soft and malleable once, on initial (properly done) assembly. Yeah, a few caveats there, but even then, re-annealing is possible.

So, IMHO, go ahead and quench, especially if in any hurry.

Well, yes, I reckon that is reasonable advice. However, the "slow" cooling required for an injector copper washer seal takes all of 5 minutes, sitting on a bit of (gasp) asbestos or other heat resistant stuff. And, IMO, the softer and more malleable the better in such applications.

Each to his own!

Jim