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Old 30-11-2007, 04:30   #16
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The compression numbers don't bother me too much. Get the repitch done and see how performance is. I'll bet the rings on the 2 low cylinders have light tension or the walls are starting to glaze. It's common to have an engine with low hours to be like this. Usually it's owner abuse, or better not proper use. I'm starting to call it lazy engine syndrome. My guess is the PO babyed it. probably never went much over 2500. Let it idle 10 min to warm up and cool down, only motor the minimum necessary to get out of the marina. If you had said it was a 1996 with 200-500 hours on it. I'd be content in my diagnosis. 1500 I'm not so much.
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Old 30-11-2007, 11:27   #17
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A very accurate test is a differential pressure test. You use compressed air which is passed through a calibrated orifice.
Yeah Dan, that's what I was refering to as the "Leakdown" test. Sorry, I didn't know you guy's had a different term for it.
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Old 30-11-2007, 11:58   #18
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Alan,
We do refer to it as a leakdown test here also.
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Old 30-11-2007, 18:42   #19
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A wet test is where you put a small amount of oil into the cylinder
This would be done IMHO if the results of a dry test were not within spec.
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Old 01-12-2007, 00:28   #20
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I don't think that you have an engine problem. Sounds more like prop pitch problem to me too. Those high-RPM diesels don't like to be over-proped. They smoke like the dickens due to over injection of fuel that can't be burned. Me dost think that you may be over-thinking this thing.

Take the most obvious and easiest step first (prop pitch). If that doesn't fix it (I think it will) then look for other solutions.

However, I would make sure that you check your valve clearance again at .008 inch. You don't want to solve one problem and create another.
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Old 01-12-2007, 05:51   #21
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and they said AMEN. Many Many thanks to you all. Most is what I thought also. I will set valves and follow up with the TEST and post results. It may be spring, But I will be back.
Again THANK YOU for your insite and concern. sailors are the most wonderfull people. Some day in some chow line, we will meet. Thank You
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Old 25-03-2008, 13:21   #22
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Usually the black smoke while under load is an indicator of over loading ie to much prop pitch. However if it didn't smoke before and does now then something has changed. It may be something as simple as a clogged air filter. Pop off the Air filter cover. Inside you will find a Conical sponge filter that is supported with a metal screen. Just remove the sponge and clean it. Then reinstall and try it again. Remember the Black smoke is really not enough air for the amount of fuel being injected. This usually is overload but if you restrict the air supply you will get the same result. The basic formula for trouble shooting is always start at the most simplest cause and work towards the most complex. Good Luck
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Old 25-03-2008, 15:16   #23
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Don't worry about doing anything until you change the pitch of the MaxProp. Once you are able to get to your specified maximum rpm, if you are still getting smoke, then check the other things. I wouldn't be overly concerned with your compression readings unless the engine is hard starting, and if it is hard starting or smoking, I'd check the injectors or the fuel pump first.
But, I wouldn't doing ANYTHING until I got the MaxProp pitched correctly (they can be very tricky)!
Brian
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Old 25-03-2008, 17:23   #24
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As a Yanmar dealer,over proping is a common problem. The first thing we look for is can it hit 3600 rpm. Get me your gear ratio, water line length, gross weight, prop size, how many blades
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Old 25-03-2008, 20:11   #25
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It will go 3600 but not in gear. I have to check on the gear ratio, 27 at WL, 11k and three blade on a one inch shaft and I have to check the size. I called max prop when I had it hauled out. I have several settings they gave me. I will be reseting in the next week or two. If the settings they gave are the same as what it is set at, I will post more questions. Thanks for checking on me
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Old 26-03-2008, 08:02   #26
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Originally Posted by Badsanta View Post
It will go 3600 but not in gear.
LOLOLOLOL...
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Old 26-03-2008, 09:03   #27
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It will go 3600 but not in gear. I have to check on the gear ratio, 27 at WL, 11k and three blade on a one inch shaft and I have to check the size. I called max prop when I had it hauled out. I have several settings they gave me. I will be reseting in the next week or two. If the settings they gave are the same as what it is set at, I will post more questions. Thanks for checking on me
it's overloaded, simple as that. There is a way, way outside chance the engine is down on power, but I doubt it. Get the prop dialed in and then we can talk about questionable engine problems.
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Old 26-03-2008, 16:14   #28
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And just in case you missed the comments from several, I suggest you have a simple over propped issue. If the engine can run at 3600 in neutral, it must be able to get within at the very least, 10% of 3600RPM in gear. So 3300RPM would be about spot on. You won't operate that hard, it just has to be able to get there if you opened the throttle.
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Old 01-04-2008, 11:49   #29
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And just in case you missed the comments from several, I suggest you have a simple over propped issue. If the engine can run at 3600 in neutral, it must be able to get within at the very least, 10% of 3600RPM in gear. So 3300RPM would be about spot on. You won't operate that hard, it just has to be able to get there if you opened the throttle.
Alan, with all due respect, it is crucial (IMO) that the engine be able to reach max RPM (and maybe 5% more) under ideal conditions.

If you look at a power curve on that engine (as on most engines), I think that you may discover that peak HP is reached at about 10% below max RPM. If the engine can merely attain 10% under max RPM during ideal conditions, it may well fall far short under demanding conditions because it will never be able to reach it's intended potential.

If the rated HP is 28 @ 3300RPM and the engine is only able to attain 2500RPM (or less) under demanding conditions, the engine may only be developing 1/2 of it's potential. The max RPM under demanding conditions will deteriorate rapidly due to the lessened available HP, which in turn will hinder it's capacity even farther.

It is far safer to be slightly under-propped (IMO) than over-propped. That way, you will be assured of maximum available HP when it is needed most.
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Old 01-04-2008, 12:50   #30
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Alan, with all due respect, it is crucial (IMO) that the engine be able to reach max RPM (and maybe 5% more) under ideal conditions.
No, you have to understand the different terms being used and sadly, not ALL the story is told in the specs with some. But youy specs shoudl tell you several different key points.
Max RPM is a short term unloaded rating. It is the Maximum RPM that the engine will rev to before the Govoner cuts in a limits the engine from going any further. This speed is not something you want the engine to be able to achieve normaly. You then have a "short term" maximum rating. This is where the Power peaks on tha Graph and is what most manufacturers will use as the HP rating. But this RPM is still not a continuous rating. The continuos rating is the RPM where the engine will happily run all day every day with out over heating the engine. Which spec is being used, depends on the engine manufacturer.
So the easiest way of determining all this is a simply industry rule of thumb. Reve the engine unloaded and see what the rev counter tells you. Place in gear and do the same. The max differnce should be around 10% by rule of thumb. If you sit within 10%, the bet is you are pretty close to spot on. It's not me that came up with it. It is a general inudstry recognised rule of thumb that brains bigger than mine have used for years.
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