I have a 2001 250hp ox66 Yamaha. It has 225 hours on it. Last week I took it out and while running at 4200rpm's thought I hit something soft (like some floating grass, algae, or a crab trap line). The rpm's fluctuated a bit so I brought it back to idle. It stalled.
I ended up checking the prop and all seemed fine. It ran perfectly all day long. However, by the end of the day I noticed a "tapping" sound. It is very evident at idle and low speeds. After searching this site and hulltruth I decided to check/clean the O2 sensor and VST filters. The O2 draw tube had a ton of carbon / oil buildup on the outside. However, after a thorough cleaning and replacing the draw tube it did not solve the problem. I checked compression. 110-120 all cylinders. By the way, the motor is running great.
After searching this site thoroughly I noticed that many are experiencing this same "tapping noise". Unfortunately, the "fix" has not been posted.
Obviously I am concerned about major engine issues (broken ring, wrist pin, etc). However, I do not believe that this problem is that serious. Could it be related to the drive shaft? Noisy fuel pump? DO YOU GUYS HAVE ANY OTHER IDEAS??
I am taking it in to the Yamaha shop within a couple days. If I figure this out I will post. Hopefully others will benefit.
I ended up checking the prop and all seemed fine. It ran perfectly all day long. However, by the end of the day I noticed a "tapping" sound. It is very evident at idle and low speeds. After searching this site and hulltruth I decided to check/clean the O2 sensor and VST filters. The O2 draw tube had a ton of carbon / oil buildup on the outside. However, after a thorough cleaning and replacing the draw tube it did not solve the problem. I checked compression. 110-120 all cylinders. By the way, the motor is running great.
After searching this site thoroughly I noticed that many are experiencing this same "tapping noise". Unfortunately, the "fix" has not been posted.
Obviously I am concerned about major engine issues (broken ring, wrist pin, etc). However, I do not believe that this problem is that serious. Could it be related to the drive shaft? Noisy fuel pump? DO YOU GUYS HAVE ANY OTHER IDEAS??
I am taking it in to the Yamaha shop within a couple days. If I figure this out I will post. Hopefully others will benefit.