Yanmar 6LP Preheater

[johnmurray]

I had an alternator failure in my engine and the cause was found to be a failure of the controller, relay in the preheating system. What happened was the engine would start with the glow plugs working at start-up, but they did not shut off after the engine was running. This, in turn, caused the alternator to overheat and fail. When the alternator was replaced, and the preheater system was disconnected the alternator worked as it should. Given the warm weather we have up here in the summer and no boating in the winter, the preheating system appeared redundant. However a Yanmar representative told me that the preheating system also was a necessary function in controlling engine carbon buidup and should be functioning on start up regardless of the climate.
Has anyone else had a similar experience.
John Murray Albin 30FC katieg, Ottawa Ontario

[Jkraft]

I had an alternator failure in my engine and the cause was found to be a failure of the controller, relay in the preheating system. What happened was the engine would start with the glow plugs working at start-up, but they did not shut off after the engine was running. This, in turn, caused the alternator to overheat and fail. When the alternator was replaced, and the preheater system was disconnected the alternator worked as it should. Given the warm weather we have up here in the summer and no boating in the winter, the preheating system appeared redundant. However a Yanmar representative told me that the preheating system also was a necessary function in controlling engine carbon buidup and should be functioning on start up regardless of the climate.
Has anyone else had a similar experience.
John Murray Albin 30FC katieg, Ottawa Ontario

I was told by a previous owner that the pre heaters stayed on and burned them up, but it didn’t kill the alternator. That problem was corrected since and they work great. When they turn off the alternator should bring the voltage back up. It’s a huge draw so if they are staying on I would think you would notice it on the volt meter. I like having mine, especially this time of year. It does help clear start up smoke faster as well. I am in the process of upgrading my alternator now but it’s not related to the heaters. I recall reading that the heaters were a optional item for cold climates, so I don’t totally buy that they are “required”. May be worth a call to Mack boring to find out

[Tree]

Later engines had them fitted. Earlier engines without. Mine does t have them or ever had them - I’ve used the port where the bolt blanks it off as my take off for my boost gauge.