| |
 | |
|
Originator: Robert
|
Guest
|
Date:
07 November, 2009 - 03:45 PM
|
Yanmar SB8 won´t power sailboat at low RPMs (less than 1500 RPM)
I have a Yanmar SB8 in a Hunter 27 Sailboat.
Problem: Engine will not continue running with prop shaft engaged at less than 1500 RPM (Tach Measured). The Engine will idle down to around 750 RPM if the prop shaft is disengaged (in neutral). But if transmission is engaged while at idle, it will lug down and halt. This is particularly annoying during docking maneuvers.
To maintain a low speed, I must engage the propshaft, begin coasting, then disengage the prop shaft so as not to go too fast.
One of the spring tension mounts in the governor linkage wore out and had to be repaired, and we did follow the Governor linkage adjustment as given in the Yanmar SB8 Service Manual, but I wonder if there may have been changes which were not incorporated into the manual?
The engine was rebuilt at a qualified Yanmar area distributor site in 2002 (Mack Boring, in Massachusetts), so I am confident the job was done right.
I currently have 374 hours on the engine, and did have the Mack Boring Intro to Diesel Course (Diesel Engines), so am familiar with the engine.
The engine Maxes out (on Tach), to 3000 RPM, so the range seems correct (should be 3200 but Yanmar says not to run it there except as a test).
Prop shaft turns easily by hand with transmission in neutral, and out of water, the prop turns slowly with the engine running if not restrained, so the transmission seems correctly adjusted.
Any ideas on where to go from here?
Change Governor link adjustment? If so, in which direction?
I realize the governor link is set to enable the engine to run in accordance with the throttle setting, but ought not the engine also increase power if the prop tends to slow down the engine, much as as 2- stroke lawn mower or snowblower might when loaded?
Thanks for your suggestions and / or insights,
Bob |
| |
|
|
|
Response #1 from: Ed
|
Level 1 Member
|
Date:
07 November, 2009 - 07:00 PM
|
|
(Archived Message - Members Only) |
| |
|
|
|
Response #2 from: Ski in NC
|
Level 3 Member
|
Date:
07 November, 2009 - 07:11 PM
|
|
(Archived Message - Members Only) |
| |
|
|
|
Response #3 from: hugh C. Brock
|
Level 1 Member
|
Date:
08 November, 2009 - 08:39 AM
|
|
(Archived Message - Members Only) |
| |
|
|
|
