Yanmar 1GM

[copaco]

I cannot retrace where I read that if the engine does not start, cooling water could accumulate and when the engine would run a damage (gasket) would blow.Is this the head gasket?

[Compass790]

Originally Posted by copaco

I cannot retrace where I read that if the engine does not start, cooling water could accumulate and when the engine would run a damage (gasket) would blow.Is this the head gasket?

it COULD blow head gasket if water can back up enough to go down exhaust valve.
I see you said you need an exhaust elbow. My advice is to buy or make a stainless steel one. Google exhaustelbow.com if you are in the USA & want to buy. The Yanmar cast iron ones are not good & waaay overpriced.

[copaco]

On thé ´´throtel’´ there is also a very small screw facing aft.I presume that it is for final ajustement of idle?

[copaco]

I cannot find how to post a new thread.I would like to know if the counter-clockwise compas rose used in adjusting a compas by Compas adjusters .com Australia can be used elsewhere than in east longitude location?Can the sun shadow method be used everywhere?

[Wotname]

Originally Posted by copaco

I cannot find how to post a new thread........

Go to the "FORUMS" tab near the top left sideof the screen. At the bottom of the pull down menu there is a green button labeled "+ Start a Discussion".

Click on this green button and follow the prompts to start a new thread.

[copaco]

At idle the rpm on my sb 8 varies ,almost stalls (there is name for this).The regulator arm only has 2 springs.Is the idle rpm ajustable.Could their be a problem in the governor?

[Pegu Club]

Our old Yanmar SB-12 did not have an oil filter, it had a strainer type of thing, that one removed and cleaned then reinstalled when doing oil changes.
Stout little single cylinder engine, loud as hell though, shook the whole damn boat when it was running.
It came stock on our 1977 Bristol 29.9, we have since replaced it with a Beta 16.

[Halifax Sailor]

I also have a ysb8, circa 1978. have attached similar pic of mine, does not have oil filter, just the screen that you twist. Have also attached shop manual that i have found very helpful. My ysb moves my 1980 Mirage 27 at 5.8 knots into waves and wind while burning a measly .6 lt an hour. Yes loud but calms down at about 2500-2700. always starts, very simple and very easy to work on. 3 oil changes a season (1 lt per) and I flush it with descaler and then winterize at end of season. As the motor did not come with air filter found one from K&M filters thats fits and works well.

[Halifax Sailor]

so file for manual is too big to post, I can send thru email if you want it.

[Wotname]

Originally Posted by copaco

On thé ´´throtel’´ there is also a very small screw facing aft.I presume that it is for final ajustement of idle?

Originally Posted by copaco

At idle the rpm on my sb 8 varies ,almost stalls (there is name for this).The regulator arm only has 2 springs.Is the idle rpm ajustable.Could their be a problem in the governor?

I don't have a definitive answer you but I can explain the idle "adjustment" works on my YSE 8 and I believe (95% sure) that your SB 8 will be the same especially as they share the same injection pump. I also note that every service manual I have read for all of this family of engines are strangely silent on the throttle / idle / stop arrangements. There is plenty of detail on how to set up the regulator arm and the injection pump but none the throttle linkage.

So I hope the following helps.

There is no direct idle adjustment.
There is no seperate stop lever on the injector pump.
There is only one lever on the injector pump (regulator arm) to control everything from stop to idle to full power.
Therefore the remote (cockpit) throttle lever must have enough range to move the regulator arm on the injection pump though all these positions but it does it indirectly (by moving the governor arm).
There are two springs on the engine mounted throttle linkage - one connects to the governor arm and the other the engine block.
The heavier spring (that is connected to governor arm) allows for the throttle to set the RPM (from 0 to idle to maximum).

The lighter spring (attached to the block) is more curious. On some installations I have seen it set so it maintains some tension on the governor arm to maintain idle speed and it's tension has to overcome to stop the engine. On other installations it is simply there to remove slop from the remote throttle components and in these instances, idle is achieved by careful manipulation of the remote throttle lever. I don't know how Yanmar thinks it should be used as the manuals I have seen do not describe it's functions or setup.

It would be helpful if any YSE/YSB/SB 8 (or 12) owner can elaborate on how it works in their installation or have any written Yanmar data describing the setup of this spring. Please note, YSM has a different injector pump and I presume a slightly different throttle arrangement to achieve the stop / idle / full power functions.

[Wotname]

Originally Posted by Wotname

I don't have a definitive answer you but I can explain the idle "adjustment" works on my YSE 8 and I believe (95% sure) that your SB 8 will be the same especially as they share the same injection pump. I also note that every service manual I have read for all of this family of engines are strangely silent on the throttle / idle / stop arrangements. There is plenty of detail on how to set up the regulator arm and the injection pump but none the throttle linkage.........

OK, after a photo of the OP's engine, my above post is off the mark, it fell into the 5% area

So for a better explanation of the idle arrangement on the OP's SB8, see post 9 here Yanmar SB8 clutch control - Cruisers & Sailing Forums