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Go Back   SailNet Community > General Interest Forums > Gear & Maintenance > Engines > Diesel
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Diesel This is a new forum dedicated to diesel engines and their applicable accessories.


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  #21  
Old 05-10-2012
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Re: Runaway Yanmar 2qm15 HELP!

Quote:
Originally Posted by miamiz View Post
Thanks Paul for your help. The 2QM15 is a pretty simple engine..no glow plugs or turbos or anything. Just fuel, air and combustion (which makes this that more frustrating!). I did take the injector pump and have it rebuilt. Also I did do a garage analysis of the oil. Poured it into a glass jar and let it sit for a few days. There was no visible separation but there was muddy (cabon I assume) at the bottom when I dumped it out. Checking the crank case ventilation hose & housing is on my list of things to check. I'll try running disconnected. Just bought an oil pressure gauge so I'll get some reading on that too. Will also make some temporary injector shims to see if adding additional space will have any impact. I will also pull the head and drop the intake valves to see if I can see any oil residue. Theoretically, it should be dry right? Also ordered a new head gasket. The thought of pulling the engine the third time makes me want to learn to actually "sail" my boat! LOL
Depending on the condition of the engine some blow-by vapors may condense
and be visible in the intake manifold but I wouldn't think there should be puddles of oil anywhere. Intake valves should be fairly clean. If the pump/ governor assembly is all in one housing I guess you can assume it was properly re-built?? If you took out the cam maybe it wasn't re-installed in the right position although some cam drives I have seen are off center so you can only install them in the correct position but the cam marks and crank marks need to be aligned. I think that if the timing was very far off it wouldn't run
at all. The 3 to 4 second "breathing" thing has me puzzled? So far all I can think of is:

1. Bad pump/governor
2. Timing way off
3. Lube oil getting into the intake tract, if that is happening I think the engine would go beyond 3,500 RPM and eventually scatter. If it stops at 3,500 I would suspect the governor/"throttle" linkage or assembly is stuck on "full open"

If you don't have a really good detailed shop manual you should get one, well worth the cost. Let us know what you find. You may have too much faith that the pump was properly re-built? Just a thought?

Paul T
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  #22  
Old 05-10-2012
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Re: Runaway Yanmar 2qm15 HELP!

You guys are great troubleshooters! However a truly seasoned mechanic would ask the the most relevant questions first. Which should be..........wait for it........ "are you Polish by chance?" which I would respond "why yes I am! How did you know?" Because you have a 2 cylinder engine and you have a 50/50 chance of getting TDC right. Which would be the flywheel side and not the front you idiot!

Yeh I haven't verified it yet but I aligned timing marks on the crank gear with the cam gear based on forward cylinder being #1. It's the rear (flywheel cylinder)! Feeling really stupid at this point but to my defense the Yanmar manual only mentions the TDC orientation once in the entire manual and it's buried inside a paragraph in the middle of the book! I have to say that I have a new new found respect for Yanmar's if they would even start in this scenario! Let you know how it turns out this weekend. Thank god Paul is in California he can't come down to Miami to kick my Ars for waisting 2 two hours of his life!!!
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Re: Runaway Yanmar 2qm15 HELP!

Good on ya, Paul T/Dabnis.. nice job.
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Old 05-11-2012
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Re: Runaway Yanmar 2qm15 HELP!

Quote:
Originally Posted by miamiz View Post
You guys are great troubleshooters! However a truly seasoned mechanic would ask the the most relevant questions first. Which should be..........wait for it........ "are you Polish by chance?" which I would respond "why yes I am! How did you know?" Because you have a 2 cylinder engine and you have a 50/50 chance of getting TDC right. Which would be the flywheel side and not the front you idiot!

Yeh I haven't verified it yet but I aligned timing marks on the crank gear with the cam gear based on forward cylinder being #1. It's the rear (flywheel cylinder)! Feeling really stupid at this point but to my defense the Yanmar manual only mentions the TDC orientation once in the entire manual and it's buried inside a paragraph in the middle of the book! I have to say that I have a new new found respect for Yanmar's if they would even start in this scenario! Let you know how it turns out this weekend. Thank god Paul is in California he can't come down to Miami to kick my Ars for waisting 2 two hours of his life!!!
Miamiz & Faster, thanks. I hope that is the problem, easy to fix. It is amazing to me that it would even run that way, let alone run up to 3,500 RPM. Not a waste of time at all, one can always learn from other's experiences. Let us know how it works out.

Paul T
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Re: Runaway Yanmar 2qm15 HELP!

OK, I think I have got it? If you used #2 piston for TDC the timing is 180degrees retarted. Every engine, gas or diesel, that I have worked on uses Piston #1 for TDC settings. Which means:

1. The real intake stroke becomes the power stroke
2. The real compression stroke becomes the exhaust stroke
3. The real power stroke becomes the intake stroke
4. The real exhaust stroke becomes the compression stroke

So what, you ask? The fuel is being squirted in on the intake stroke and eventually accumulates to the point of being enough to ignite on the compression stroke. As the fuel is not all being burned because of the mixed up strokes more accumulates and the engine starts to run away.

I think

Anyway the timing thing is easy to fix, let us know.

Paul T
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Old 05-11-2012
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Re: Runaway Yanmar 2qm15 HELP!

Quote:
Originally Posted by dabnis View Post
OK, I think I have got it? If you used #2 piston for TDC the timing is 180degrees retarted. Every engine, gas or diesel, that I have worked on uses Piston #1 for TDC settings. Which means:

1. The real intake stroke becomes the power stroke
2. The real compression stroke becomes the exhaust stroke
3. The real power stroke becomes the intake stroke
4. The real exhaust stroke becomes the compression stroke

So what, you ask? The fuel is being squirted in on the intake stroke and eventually accumulates to the point of being enough to ignite on the compression stroke. As the fuel is not all being burned because of the mixed up strokes more accumulates and the engine starts to run away.

I think

Anyway the timing thing is easy to fix, let us know.

Paul T
Forgot the 3 to 4 second "breathing" thing. Could be that with the valve timing being so far off that on either the intake or compression strokes a valve is partially opening or closing allowing the intake or compression gases to escape very slowly, I think?

Paul T
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Old 05-13-2012
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Re: Runaway Yanmar 2qm15 HELP!

miamiz,

If you are still out there I am curious to know what you found and how it all came out?

Paul T
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Re: Runaway Yanmar 2qm15 HELP!

Hey Paul. I keep my boat on a city moring. Went out there on Saturday but they shut down the shuttle boat that takes residents to their boat. 15MPH winds and 1 foot swells and the guy has the nads to call himself a captian! Yeh I chomping at the bit to get out there. Promise to post a followup. EZ
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Old 05-14-2012
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Re: Runaway Yanmar 2qm15 HELP!

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Originally Posted by miamiz View Post
Hey Paul. I keep my boat on a city moring. Went out there on Saturday but they shut down the shuttle boat that takes residents to their boat. 15MPH winds and 1 foot swells and the guy has the nads to call himself a captian! Yeh I chomping at the bit to get out there. Promise to post a followup. EZ
He is probably afraid of being sued if someone got some spray on them
Hope it is the timing thing, easy to fix.

Paul T
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Old 05-15-2012
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Re: Runaway Yanmar 2qm15 HELP!

Great discussion. Miami, hope things get sorted out for you, and the re-timing solves your problems.

A couple of comments based on my own experience with my 2QM15 last year...
First, those shims under the top of your fuel injection pump are critical to its proper operation. If it's shimmed too low, the stroke will be way too long on the pump and it will pump a LOT of fuel at idle. My installed engine's pump has three shims stacked under the top. My spare engine has two shims. Total thickness is 15-20 mils, but that is a high percentage of the total stroke on the pump. If they have been tossed, and not reinstalled, you need to replace them with enough stack height to get the engine back to idle speed with the throttle at idle.

Second, the governor attachment to the fuel injection pump is a PITA and you gotta make sure to get it done right. When I replaced an injection pump last year, it took me about three hours to sort how to hook it up and get it hooked up right. The rack on the pump is a finely tuned, low friction mechanism and if it isn't exactly right, the throttle control and governor will bind, prevent throttle control, and could cause engine speed to run up to max. If I hadn't had the tech manual to puzzle over, I don't think I would ever have gotten it hooked up right. You can't get the governor connected to the rack properly without the top of the fuel injection pump lifted, and you have to settle the top of the pump into place with the rack and governor in the proper position. Once they are in place, you can tighten the top of the pump down, being careful that the governor-rack orientation doesn't shift. Also, did you check the rack adjustment for maximum "throw" and make sure it was properly set?

Won't take but a few minutes to pull the governor inspection cover and check out the governor and injection pump rack. Move the throttle through full throw and see that the mechanism pushes the fuel rack forward smoothly, and that it returns when the throttle is released. I know you had to have the cover off to reinstall the injection pump (didn't you?) and get it hooked up when you replaced the pump, but it might be worth another look.

Good luck.
Will
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