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Discussion Starter #1
Hello everybody who is nice enough to be reading this, thank you!

So a few months ago I turned my once submerged, recently rebuilt, 1978, engine on. As usual she started up great with a loud roar, but when I went to throttle her down she just continued reving. I shut her off manually by pushing on the linkage that attaches to the injector pump.

My diesel car engine mechanic buddy thought it could be the pump its self, said it would probably cost just as much to rebuild as to buy new, so a month later one came from Japan. We installed it but failed to get it to do anything but idle high or shut off completely. Just like before.

Some other engine savvy buddies spent a couple hours scratching their heads at it and suggested it could be a spring or something located internally that regulates the throttle linkage.

Before this she also had a tendency to spit black sooty water out of her cooling system but I've gotten used to this. I switched out my prop and replaced the mixing elbow which helped a little.
Any thoughts?
:confused:
 

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Did you get the mechanic to set up the timing on the new pump? Was it the injector pump you changed?

Some say it's possible for an engine with a lot of blow-by to 'run on' on its own crankcase fumes but a recently rebuilt engine shouldn't have that problem. Good news is your fuel cutoff still works.

Does there seem to be a lot of pressure at your oil fill cap when it's running? You'd have to start it without the cap on to see.. There should/may also be a crankcase vent fitting that shouldn't be plugged ..
 

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I'm with Faster on this one -- more troubleshooting is in order.

If you replaced the injector pump with a new unit (or had the original rebuilt at a good shop), then I'd be very surprised if the pump is your problem.

I am not familiar with the YSE 8, but as Faster said it may be timing related. If you have a shop manual, read that section and check your engine against it.

What was actually done when the engine was rebuilt? Was any machining done or was it just a parts replacement exercise? If they didn't hone your cylinder you might be getting excessive blow-by, even with new rings.
 

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Discussion Starter #4
I tried to Check the oil while my engine was running once and it sprayed in my face. Is this what you mean by excessive pressure? By recently rebuilt I mean in the last two years. The mechanic who installed the pump didn't really know how to time a marine engine. I also agree the pumps not the issue so then what is? Yes it could be timing. My manual suggests installing shims to adjust the timing but I have no idea where to begin in doing this.
 

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Also what is blow-by?
"Blow by" is when you don't have a good ring seal, and the high compression in the cylinder leaks by, pressurizing the crankcase. This is why I asked about having the cap off while running.

The crankcase is normally vented via your 'positive crankcase vent (PCV) back into the air intake to keep the smell and fumes down. If you have blowby it's possible that there's enough 'fuel' in the fumes that the engine keeps on running, or 'runs away' despite the governor's best efforts.

The one thing in your scenario that points away from that problem is that you were able to stop the engine with the fuel cutoff - which likely wouldn't have worked if you were in fact running on fumes. In that case the only way to kill the engine is to block the air intake.

Hopefully it was rebuilt by pros, but these are not complicated engines and a good mechanic should be able to sort things out in short order.

Good luck..
 

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I tried to Check the oil while my engine was running once and it sprayed in my face. Is this what you mean by excessive pressure? By recently rebuilt I mean in the last two years. The mechanic who installed the pump didn't really know how to time a marine engine. I also agree the pumps not the issue so then what is? Yes it could be timing. My manual suggests installing shims to adjust the timing but I have no idea where to begin in doing this.
If the oil sprayed in your face it is an indication that there is very high pressure in the crankcase. Maybe the engine oil is over filled? You might try blowing back through the crankcase breather hose from where it goes back into the intake manifold. Or if there is a PVC valve blow back from there. There should be littlt to no resistance. If there is, I suggest you replace the hose and PVC valve, if there is one. If there is oil leakage at the fromt or rear main bearing seals that may be another indication of excessive crankcase pressure.

Sounds like the injector pump may be faulty or not timed properly?

Black sooty water in the coolant may be from a blown head gasket? Perhaps another cause of high crankcase pressure?

If you don't have some experience with all of this a GOOD diesel mechanic may be a good investment. I think you said your original mechanic said he didn't know how to time a marine engine? That is a pretty basic skill for ANY diesel mechanic to have. Let us know what you find.

Paul T
 

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The mechanic who installed the pump didn't really know how to time a marine engine.
I humbly suggest you find another mechanic -- timing has nothing to do with intended application (whether automotive, marine, industrial or agricultural.) If he thinks there is a difference, then he's not the guy you want poking around on your engine.
 

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Here is another manual:

http://sailingboatefaki.gr/Engine Manuals.htm

Look at page 18. I cannot quite follow what they are talking about but looks like some speed governor parts can fall out or be damaged when removing the fuel pump. Maybe some parts of the governor system are now damaged or even missing.

Note page 39 and 40 of above manual talk about using shims on the fuel injection pump to set the engine timing.
 

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Good work, casey!
 

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http://sailingboatefaki.gr/Engine Manuals.htm

On Zip File 4 (Parts List) of above link (pages 27a and 29b) you will find the diagram of the governor system. Check the external springs for throttle return are all on your engine and working. Could be a problem with the internal governor as shown on the diagram.
 

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Discussion Starter #13
Hey it has been a while since I posted anything on here.
Anybody still following the thread, the mechanic who recently rebuilt my engine didn't tell me explain the details, just that it was submerged partially and he kicked it back to running. It ran great for a year or so with the exception of the black sooty water out the cooling system. I replaced some of the pipes and this seemed to help a bit. It doesn't seem there is a cracked head gasket as of now because I run it extensively without any explosion. It has spit diesel and oil out from somewhere and its oil leaks do seem to be increasing. I have a few folks take a look at it and nobody has been able to diagnose the issue but could be there is an internal linkage regulator issue.
I'm taking it to a pro tomorrow so we'll see how it goes...
 
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