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Old 17-12-2005, 19:17   #16
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Woody, here is another wee test to do. Start the engine and then remove (carefully) the oil filler on top of the rocker cover. Is there any pressure and any white fumes being blown out???
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Old 17-12-2005, 22:25   #17
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Good point Wheels, let me rephrase. Are the injectors new, or reconditioned?, and yes, checking the blow-by will be very telling.
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Old 17-12-2005, 23:55   #18
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Yeah I had been thinking along a similar line. Hey Woody, I hope it helps you in knowing, that some of us a thinking about this situation whiles lying in bed trying to sleep.
Anway's, I wondered if they were new, if anyone had actually set them? It could be that one is not atomising the fuel and just squirting it. It could also be that one has been dropped and had the tip damaged. It has to be a very low pressure squirt, but such would probably not combust. If there was any combustion at all, the smoke would imediatly turn black. Just one more thought.
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Old 18-12-2005, 07:40   #19
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The statement that is the most telling to me is...
The engine sounds great. Low vibration and no wierd sounds of pre/post igniton, pinging, etc. In fact a certified diesel large engine mechanic happend to walk by, saw the smoke (it really isn't that bad, but I do expect near-perfect I suppose) and declared that she sounded great.

I'm thinking he's never broken it in completly, even the first time.
Check the blow by with the oil cap. If you have the tools check the leak down.
If not...GO RUN THE STINKIN SNOT OUT OF IT, beat it whip it...make it write bad checks for at least an hour. Preferably 2 or 3 hours. then let it cool over night and see what happens.
It's imposible for you to overrev it intentionaly, the govenor will control it. The engine was designed to be cruised at 2800-3200 run it there and recheck.
I'm not trying to be harsh, I just don't write well.
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Old 18-12-2005, 10:24   #20
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Never Monday makes a VERY good point - breaking in a rebuilt or rebored engine. Until the rings seat in their grooves and polish the cylinder wall surfaces one can expect a lot of oil bypass, etc.
To speed the break-in process, use a *non-detergent* oil for a short time.
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Old 18-12-2005, 11:42   #21
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Yes I agree with Pat. I shouldnt' have come up with so many idea's. It is easy to get side tracked and mislead into areas that you need not go.
Run it in. Run it hard UNDER LOAD!!.
WATCH the temperature. A tight engine will get hot quick and you don't want to over heat it. You want to clock up a good 8 hrs under hard running, WATCH THE TEMP,and then change the oil.

Remember, when you start a deisel, you want to get it into gear as soon as you can and allow it to warm up under load. Don't allow it to warm up by idleing or higher RPM under no load. As you found out the first time.

Start engine, allow oil pressure to come up, place into gear and take strain on lines, then raise RPM to about 1/3rd for just a couple of minutes. This allows cylinders, valves and mainfolds to warm slowly and evenly and reduces the risk of cracking. Then raise RPM to 2/3rds and allow temp to come up to normal operating. Once you have reached normal operating, you can go to full power for about 5mins before shutting down. This should be done every two weeks or at least once a month.

If you are leaving the maina, just get it into gear and go.
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Old 20-12-2005, 10:52   #22
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Gentlemen,

I'm sorry I haven't responded to all of your thoughtful ideas regarding my rebuilt Yanmar but I've been called away to a family emergency and this has takedn me away through the Holidays (outa country actually.)
But qucikly:
1 - Brand new injectors had 20 h on them prio to rebuild. Were pop tested at injector shop with injector pump. Were good and no, not dropped.
2 - White smoke may? smell like diesel but hard call. Certainly leaves sheen on water and not blue and not steam (so not water mixing)
3 - 3 hrs now on rebuild and I will follow hard break in as suggested (and of course get her up on temp first) and under load.
4 - May well be just need break in period. I put the pistons in and they were tight ! Who knows, diagnosis may result in cure.
5 - I will recheck that injectors are firing and pattern is to spec.
6 - I'll recheck valve gap after break-in.

thanks to all, I'm gone for a week, Happy Holidays, Woody
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Old 08-02-2006, 19:40   #23
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So Woody, it's been a few weeks, any success?
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Old 18-02-2006, 14:10   #24
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Hi,
I've come across this problem about 3 times now, in 3 cylinder yanmars, but they were used as generators, although plus or minus it's the same motor as a 3JH.

I think you've got a bent con rod. It was white smoking before you pulled it out. Sounds like you did a top overhaul job, but it still white smokes.

If you try and start these engines when they hydraulic lock due to Seawater getting in the exhaust ( antisyphon valve, big wave up the stern ?) they tend to bend con rods, and then white smoke. Due to low compression on the affected cylinder!

If you pull the inectors, you may be able to measure the piston height at TDC by putting a rod down the injector port at comparing one piston to the other.

Hope it's not a con rod, but sounds like it to me.

Regards
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Old 13-04-2006, 18:01   #25
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I just rebuilt the upper end of a Volvo MD17D. It is 20ys old and has around 4000 hrs. It was producing too much smoke.

Getting it started in the cold winter after the rebuild was very difficult, but when it did start up it threw lots of white smoke decreasing as the engine temp made its way up to operating temp and then the smoke is very light, but it is there... almost unnoticeable.

The upper end rebuild (new heads) along with a new fuel pump and raw water pump has the max engine RPM up where it is supposed to be. I also cleaned the exhaust bend and replaced the exhaust hose. Compression seems good, but cold air is a hard one for this engine. I suspect the white smoke is coming from the rings/pistons which are original.

The rebuild has definitely improved the engine performance, lessened the smoke, but there remains a bit of oil slick.. un burnt diesel in the exhaust... which I attribute to the lower end.

Having a large clear unrestricted exhaust hose with no kinks seems to be important as well. Let's see how this works out when we sail this season...

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Old 16-04-2007, 20:07   #26
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Hmm, wonder what ever happened to Woody?
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