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Discussion Starter · #1 ·
Has anyone cleaned their injectors before and what were the results? I just pulled out the injectors on my 1991 Yanmar 3GM30F as the engine was becoming quite hard to start when cold (otherwise ran ok). Several shops said it "probably" is the injectors. I had read it could be quite difficult to remove them so I was prepared with an array of tools, liquid loosening agents and pry bars. All three were out in about 5 minutes!! Very simple. Each had carbon sludge built up around the nozzle so I took them apart, cleaned with a toothpick the valve case inside and out and also the nozzle tip. No big deal at all. I did not get into the spring stuff- looked ok. So you "gotta fix everything myself types" like me, what success have you had doing this on the way the motor runs and starts??

Thanks!
Dave
 

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Corsair 24
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remember to install them correctly do these use shims?

edit: found they are supposed to use 2 shim washers per injector

cheers
 

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Mechsmith
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Now you have them out I would prefer to take them to a diesel injection repair shop or read the test and spray proceedures from a shop manual. They are all more or less similar but a common problem is erosion at the tip which messes up the spray pattern. Water in the cylinder is the main cause of this.

But if it was me and my own I'd probably put them back in and see if I gained anything.

If you have pre heaters test them with an ohmeter. They go bad much oftener than the injecters. If they are bad they will be "open".

Be very careful with cleaning out the holes in the head. They must be very clean. A speck of carbon will make the needle run out of true and that will mess up your spray pattern or worse. Bad spray pattern means smoke, especially when cold.
 

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美国华人, 帆船
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Now you have them out I would prefer to take them to a diesel injection repair shop or read the test and spray proceedures from a shop manual. They are all more or less similar but a common problem is erosion at the tip which messes up the spray pattern. Water in the cylinder is the main cause of this.
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I would definitely send out to be cleaned and tested or DIY if you have a ultrasonic cleaner.
 

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Discussion Starter · #7 ·
Thanks you guys! Yes I could have sent them out to be done but I have found that the cost for a pro rebuild was almost as much as new ones. So I thought I'd try this first. I don't believe any harm could be done as I only used (as recommended) wood toothpicks to clean with. For those of you considering doing the same, unless you are going to get into the actual injector valve where the little parts are, this cleaning I did is something we most all could do. I will have them pop tested to see if the springs are correct and also if the pattern is correct after my cleaning. If you folks are interested I will reply back after I put them back in the engine with the results of my cleaning project.

Dave
 

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Courtney the Dancer
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What commonly happens to injectors is the tip which controls the spray pattern gets corroded or just worn with the result being fuel dribbling out instead of spraying a fine mist. An injection shop can easily test them and rebuild as necessary.
 

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Discussion Starter · #10 ·
So here is one update to my cleaning the injector post. So even though I cleaned my injectors as stated, I decided to acquire a new set just in case. That new set cost almost $600 after related parts were added... YIKES! Well yesterday I took my new cleaned injectors down to a injector shop and they pop tested them. In 20 minutes they has adjusted the pressure, checked the spray and given them all a positive bill of health...... for $59.00!!!!! They said they should function as new. Well I still need to put them back in the engine to see what happens but I learned an important lesson so far that a bit of my efforts can go along way to saving serious cash, which hopefully now could go towards a spinnaker roller furler:D. Will get back about with the in-the-engine-trial.

Dave
 

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Irrationally Exuberant
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An excellent lesson for us all Dave! Looking forward to your final results.
 

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You say you bought new injectors. Can you return if the old ones work ok?

I have a 3gm. Can you tell me how you pulled the injectors? It looks like you just remove the two hold down nuts and pull off. But looking at the Yanmar drawing there is a lot of parts that fit between the injector and head, like washers and insulators. Do these get disturbed, or do these just remain in place?
Regards
 

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Discussion Starter · #13 ·
Hi Casey, pulling the injectors took only minutes for me but I have heard that other folks have had a terrible time.

After disconnecting the fuel lines you will need to remove the two nuts that hold the bridge piece, that puts pressure down on the injectors to keep them in place and tight. Once those "bridges" are taken off twist the injector body back and forth a bit to loosen it and then pull injector straight up and out. Again, mine were the originals from 1991 but were no problem. If they don't want to come out then I would apply some liquid wrench stuff, let them sit for a couple of days, then again and maybe with a wrench, try to twist them a bit first and then pry them up. I read somewhere that one guy had to get a slide-hammer to get them out :-((.

FYI, I am trying the engine out this evening to see how the repaired injectors work. If good, then I will not need the new ones I bought. If thats the case I will either return them or sell them here etc. Let me know if interested. I paid about $130 each but they were a bit difficult to find.

Dave M.
 

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Thanks Dave for reply.

My engine is very rusty (I plan to clean it and paint in the near future). I have herd one problem is having any debris fall into the cylinder on removal of the fuel injector. Was you engine clean where this would not be a problem? For me, even if I clean and paint, looks like I have corrosion well into the fuel injector area- I can imagine rust falling in when I pull out an injector.
 

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Senior Smart Aleck
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... as the engine was becoming quite hard to start when cold (otherwise ran ok). Several shops said it "probably" is the injectors...
I am surprised the shops would say that, when it could be any number of things, such as the ignition switch, the solenoid, the starter, your batteries, connections, glow plugs (if you have them), etc. If the injectors work when the engine is warmed up, why wouldn't they work when cold?

In addition to the good advice on this listserv, you might want to buy one of the diesel engine troubleshooting guides, like Peter Compton's "Troubleshooting Marine Diesels", which is also contained in Don Casey's "Complete Illustrated Sailboat Maintenance Manual" or Nigel Calder's "Boatowner's Mechanical and Electrical Manual". Those will organize you in the right direction toward the components causing the problem.
 

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Discussion Starter · #16 ·
Casey, that other comment about having some form of a manual is a good idea! But, yes you might have a problem... I guess you will find out when you get to work. As far as crap falling into the cylinders, well I guess you could turn the motor upside down while you are pulling out the injectors! Or, clean up well around the injector holes before pulling and also have a shop vac sucking while you are pulling. In the end, what really could fall in? Junk which should get blown out when you start the motor the next time. Mechanics will yell at me about that one!! Don't obsess too much, get directions and input and get-er-done.
Dave
 

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Dave,
When you say "hard to start" can you tell us what happens when you try to start the engine?

My 30 year old yanmar 3gmd has at times been hard to start. This is what I found to be the problem:

1. Once I found a poor connection from the positive lead from battery to the starter. The engine would turn over, but not fast enough to start easily. Also check your ground connections.

2. Same problem as #1 above but starter battery was getting old.

3. To start I give full throttle and then start the engine- imediately go to idle when engine starts. Note this is how yanmar says to start engine.

4. I have found too low of an idle adjustment can lead to stalling- set idle to specs.

5. Make sure air filter and fuel filters are clean as well as the fuel pick-up in fuel tank. Also check no air getting into fuel system.
 

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Casey, that other comment about having some form of a manual is a good idea! But, yes you might have a problem... I guess you will find out when you get to work. As far as crap falling into the cylinders, well I guess you could turn the motor upside down while you are pulling out the injectors! Or, clean up well around the injector holes before pulling and also have a shop vac sucking while you are pulling. In the end, what really could fall in? Junk which should get blown out when you start the motor the next time. Mechanics will yell at me about that one!! Don't obsess too much, get directions and input and get-er-done.
Dave
Good idea on the shop vac. I do have a manual- but it is not clear as to what needs to come out when the injector is pulled. I agree on debris falling in- must be a lot of worse stuff that gets sucked into an engine only to get spit back out.
 

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Discussion Starter · #19 ·
Casey, I've looked at most everything including what you mentioned. Everything about and around my engine is like new as the previous owner(s) was/were fastidious about rust and grime. As before my engine runs fine when running and starts fine when warm. The local mechanic(s) suggested I work on the injectors first. If that does not help then we start looking at compression and other stuff. I did the injector cleanup because it was easy, cheap and can be the cause- not getting a good spray when at a cold start. I was told that this issue diminishes with a warm engine. They also said the problem diminishes with a warm engine because of tighter tolerances and thus higher compression. PRAY it is not a compression issue... it should not be as I only have about 2000-2500 hours on it and these with proper care should go 7000 hrs.

I'll get back to the forum soon about my startup!

Thanks,
Dave
 

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