Yanmar SB12 Using Oil

[Homer Shannon]

Compass - [B]I'd [B]like to know if the engine is OK, but in reality I won't know how it is really doing until it's been run for ten hours or so. So, I won't learn anything by running it now other than that it seems to be properly reassembled. (If it won't run, I'm not going to try and diagnose the issue until spring.) I'll just feel a lot better when I button up the boat for winter that the motor is in running condition.

I sure do appreciate all the help you and Wotname and some others have provided. You've give me confidence to move ahead when I got into areas I was not fully versed in.

[Homer Shannon]

I received all the parts I needed to finish the conversion to an off-motor filter a week ago but it was too cold to bleed the fuel and try to start the motor. Finally today it got to about 40 degrees and that was good enough.

I finished assembling the fuel system and bled it. Then I gave the engine a test run. The motor started pretty quickly, though not instantly, and runs nicely. I didn't run it long or hard as it has no cooling water connected to it and the 30 weight oil is going to be pretty thick at this temperature. But, it ran nicely and idled much smoother than in the past - for what that's worth.

The only remaining mystery is the diesel return line coming off of the fuel injector. I expected this to expel a stead, if small, dribble of fuel. No fuel seemed to come out of it at all. Perhaps the engine has to run longer or harder for this to start to run?

Completing this, I finished snugging up the winter tarp and put the ladder away. I'm done 'til spring. Oh, I left the piston at TDC

[Wotname]

Congratulations on getting it back together and running. Let's hope your original problem has been fixed.

I'm looking forward to an update next spring / summer after you have run it for awhile.

[Compass790]

don't know if I'd expect an instant start in that temp especially with unbedded rings. I'm no injection pump expert having only done up 1 but when ours wasnt going too well it wouldnt flow anything from rtn line either. Injection shop said pump was worn out but I didnt trust that shop ( long story) altho having said that I know it had water thru it so it's likely that was true. After i put new plunger & barrel with a delivery valve in injection pump it did flow fuel thru rtn line. However you havent run yours for long so i wouldnt panic yet.
Maybe someone who actually works on injection pumps will chime in.
Glad the project sounds like an upgrade success so far.

[Homer Shannon]

I didn't expect it to start quickly either and actually just hoped it would "kick", showing some intent to start some day, probably later in the spring when it was warm. However, with some cranking it did start and ran well. As for the return fuel line, I found some indications online that the Yanmars don't actually return much to the tank. So little in fact, in some cases it did not seem to return any. I think I'm in that group but I'll find out more when I run it hard next season.

[Homer Shannon]

Well, the cover is off - just a bit late this year - and I ran the motor for a while. It started fairly easily and ran well with little smoke or other issues. My only concern is a significant amount of oil I found floating in the bilge when I checked things before starting. I'd estimate there was a cup to a pint of oil floating. There is no evidence of leaking anywhere on the motor, but if it has been weeping out of the oil pan gasket until it reached the gasket level, this would all have dripped away long ago. The level on the dipstick looks about right to at the gasket line. I didn't fill the oil all the way last fall, so I don't have a good way to know how much really leaked out.

I guess I'll have to fill the oil up and put some cardboard under the motor to try and see where it is leaking from. I noted last fall that the oil pan holds two quarts. Normally a top-up takes four quarts. I assume this means that the gasket is normally "underwater" and will leak profusely if there is a problem with the gasket. Something else to figure out.

My other main problem to solve before launch (in addition to normal items) will be to square away the prop shaft cutlass bearing. The old bearing was heavily corroded, probably because it is not bonded to the rest of the boat. I have a new one that is made out a fiber material instead of bronze. There is no way that the three dinky and pretty stripped set screws in the prop shaft tube are going to hold this thing. I'm thinking about some new set screws, set further forward where there is more material. If I drill the cutlass bearing a bit, I can run the set screws through the bearing all the way to the shaft and then back them out a bit so that they remain in the bearing but not touching the shaft. Any suggestions on this?

[a64pilot]

Cutlass bearing is supposed to be a press fit.
Mine is looser than it should be, so I “spot” mine, that means remove the set screw and mark center of bearing with an automatic center punch, then drill a small pilot hole not all the way through the metal, then drill with as large a bit as is possible without hitting the threads in the tube, then install set screws and lock with blue loctite.

[daletournier]

You can also use some epoxy to hold it in place. Only smear it on half the bearing. It can removed down the track using a heat gun.

[Compass790]

Hope my tip about using silicone on yr sump gasket isn't the cause of your oil leak! I've used it for decades so am practiced with it & dont have problems but it's possible I guess. Keep us posted what you find & how engine is after you take it for a long run.

[Homer Shannon]

Thanks, guys. I'll get out and start working to figure out the details as soon as the rain stops.

On the cutlass bearing, I'm thinking that if I pull the prop shaft out again, which won't be hard - I still have good access to it, I can wax the bearing and then inject some epoxy to fill up the very loose fitting in the prop shaft extrusion. It will be a finagle, but I think I can make it right.

Compass 790, I DO suspect that the silicone gasket is my problem, but no worries about blame. I took your advice and maybe it didn't work right for me. Should have held off a waited for a gasket to come in... if that is the issue. I'll add a pint of oil and see where it starts coming out from. It is quite possible that this is just a very small leak; after all, it has had five months to leak out. If it's super minor, I'll just build a small pan to go under the motor. But, I think putting in a new gasket is probably the right fix.

[Compass790]

Compass 790, I DO suspect that the silicone gasket is my problem, but no worries about blame. I took your advice and maybe it didn't work right for me. Should have held off a waited for a gasket to come in... if that is the issue. I'll add a pint of oil and see where it starts coming out from. It is quite possible that this is just a very small leak; after all, it has had five months to leak out. If it's super minor, I'll just build a small pan to go under the motor. But, I think putting in a new gasket is probably the right fix.[/QUOTE]

Yes I'm feeling guilty now! but not panicking yet as maybe a little nip up may fix the leak if it is in the silicone seal. I await the verdict, hopefully i'll be exonerated.

[Homer Shannon]

The rain has stopped a bit, so I took a minute to go work on the oil leak part of my issues. I placed a piece of cardboard covered with a couple of layers of cut toweling under the motor and added about 1-1/2 cups of oil, which brought the level up to the top of the hashmarks on the dipstick, which is well above the block/oil pan gasket. No immediate problems.

I'll give this until this afternoon and then go and have a look at it again. Will I be surprised if there is no evidence of leaking at all? Not a bit. There are already plenty of mysteries in this old motor!

[Wotname]

Homer, do be aware that a single cylinder engine gives the crankcase a pulsating pressure effect when it is running which effectively puts some pressure on the oil in the crankcase. Due of course to the piston moving up and down in a semi sealed crankcase.

This MIGHT be causing the oil to be pushed out of the slightly failed silicone gasket.

Multi cylinder engines don't suffer from this (unless there is a lot of blow by).

[Homer Shannon]

I topped up the oil and placed a rag under the motor over two days ago. Today I checked the motor and there is no sign of dripping and the oil is still at the full mark. This totally exonerates Compass790 - the silicone oil pan gasket is NOT the culprit for my mystery bilge oil.

Of course, I still don't know the source of the bilge oil. I can only guess that it came from various and sundry sources as the water got into the bilge over the winter. At this point I'm confident I don't have a major issue and I'll delegate the problem to a watch status.

I started and ran the motor again today. It fired up on about the second revolution and ran well immediately. The new, in line fuel filter still is only half full, but it does not seem to create any kind of air bubble issues. I searched several forums regarding this concern and the general consensus is that these filters normally have some air in them and it is not an issue.

So, it's time to get on with other preparations for launching. I'm calling the hauler Monday to set a date in early June.

[Compass790]

Whew! I'm breathing a little easier now but still a little nervous ( see Wotname post #133 for anxiety increase theory )
Anyway hope you post again after a long run when you've splashed as you need to put under load to be sure.
Was oil in bilge same colour as oil in engine? I assume engine oil would be clean.