Yanmar injectors

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captrick	Yanmar injectors		Lead	[-]
Posts: 198 04/04/06 07:49:54	Tags : None My 4JH3E engine seems to need more than it's usual share of TLC this season. At 1600 hrs I replaced the exhaust riser no problem, but with my head in the engine compartment, I notice an unusual ominous rattling noise out of gear at idle. Seems to be coming from under the valve cover but not typical valve/injector noise. Not water pump or alternator bearings. Yanmar thinks I should pull and test the injectors. That requires a special tool and is big, expensive job. My questions: 1. Anyone have an opinion on the noise? 2. Has anyone pulled the injectors and if so at what hours? Rick 704-3
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yorkrose	Re: Yanmar injectors	#1	[url]	[-]
Posts: 267 04/04/06 11:12:53	Rick, A couple of questions in response. Does the same noise persist when in-gear at idle? Is the engine hot or cold when the noise is heard? Any change in sound from cold to hot? Does the engine generally run OK, with adequate power, no smoke, etc? Two possibilities that have nothing to do with the injectors are: Some external part is rattling. The sound would depend on the vibration of the engine, which would be different in gear vs. out of gear. Something is loose under the valve cover. It seems unlikely, but possible. Loose baffle, broken valve spring, etc. It is not very difficult to remove and replace the valve cover. This should have been done already to adjust the valves. Regards, Gene Fuller Yorkshire Rose, C42 #870
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nickwigen	Injectors and Rattle	#2	[url]	[-]
Posts: 218 04/04/06 11:22:11	Hi Rick, I don't know if the injector could cause the rattle but they should be inspected and set, especially if they haven't had any attention in 1600 hrs. There is no special tool required. Disconnect the high pressure line and the rubber leak-by hose. Then loosen the nut that holds the fork-shaped injector retainer. The injector should come out fairly easily. I took ours to a local diesel service shop for cleaning, testing and adjusting. The cost was about $30/injector. I heard a story about the rattle that I haven't verified. There is a sheet metal fan attached to the aft side of flywheel with 3 bolts. If the bolts are loose the fan can rattle until it comes off and makes a big noise, smoke and panic. I can't tell from the pictures in my Yanmar shop manual if you can check the bolts and fans through the timing mark hole.
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captnron	Injectors and Rattle	#3	[url]	[-]
Posts: 51 04/04/06 13:50:49	Nick, When you replaced the injectors did you need to add any new gaskets or packing? Ron 1990 -3 cabin
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nickwigen	Re: Injectors and Rattle	#4	[url]	[-]
Posts: 218 04/04/06 14:06:44	Not as I recall. The tapered cone of the injector seals to the cylinder head metal to metal. My manual shows at teflon heat shield cylinder that fits into the head or around the nozzle but it's been about 4 years and I don't recall doing anything with it. Maybe it stayed in the head. I do know I didn't buy any parts or gaskets. To do it right you need to loosen the flare nuts at both ends of the high pressure lines. The 4 on top of the injector pump are difficult to get a wrench on and turn. I borrowed a crow foot wrench. You can Google "crowfoot wrench" and they pop up. Hope this helps.
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captrick	Re: Yanmar injectors	#5	[url]	[-]
Posts: 198 04/04/06 15:59:49	Gene/Nick, Thanks for the comments. Noise is same warm/cold, in/out of gear. Idle seems a bit rough. I looked for external rattling but see nothing. I think engine runs ok, could be light on hi-end power. Some soot on transom. Flywheel fan is interesting. Think I'll lift the valve cover and take a look there too. Nick, thanks for the encouragement on the injectors. Yanmar made it sound like not a DIY job. Of course, they wanted $95/hr+travel to look at it. I think the idea behind injector problem is they may cause misfiring and piston slap/pinging. Don't have enough experience to know if that's possible.
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mjk	Yanmar Injectors	#6	[url]	[-]
Posts: 43 04/05/06 15:43:52	I'll add to the ease of pulling the injectors...I do it every year or so and clean off the carbon that builds on the tip from low speed running thru our canal system to reach open water. It is easy to do as described by Nick and takes no more than a half-hour. I pay about the same - $25-$30 each to have them thoroughly cleaned and reset. First time i pulled them - back in '92 the local diesel shop recommended that they be numbered and replaced in the same cylinder to assure a tight seal and wear match. The stamped them 1 2 3 4 and I've replaced them in the same cylinder every time. At 1200 hours I've had no problems with the injectors. I had a Yanmar dealer tell me it was cheaper and better to replace the injectors every 1000 hours rather than have them cleaned and reset as they wanted $120 per injector to perform the service!! Too bad that dealer blew away in Hurricane Charley. MJK Splash Dancer II #94
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captrick	Re: Yanmar injectors follow-up	#7	[url]	[-]
Posts: 198 04/07/06 14:46:03	Injectors came our pretty easy. I was surprised to see they are just press fit into head. Hardest part was disconnecting the return hoses but heat gun solved that. Tips had heavy carbon coating and some rust on body. Took them to local engine shop and they cleaned and spray tested them for $85. They went back in OK and after some cranking engine started right up. Idle is noticeably smoother and engine sounds "normal". This was biggest engine job I've attempted other than changing oil and filters. Thanks all for the advice and comments. Rick 704-3
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