wi4x4man
Seaman
- Joined
- Aug 25, 2010
- Messages
- 55
Hi,
I would consider myself to be a diesel engine expert, but this one really has me completely baffled and I am wondering if anyone has ever heard of this happening.
Over the weekend my family and I had our 34' Mainship trawler out. She has a 6354 Perkins 200 Hp diesel with a BW transmission.
On Saturday, we were moving along at 7 knots (1350 RPM) when all of a sudden the engine increased in speed all by itself, and then dropped back down to 1350. I had initially figured that one of the kids had been messing with the throttle, and I gave my usual speech about not touching things.
Then yesterday while in some fairly choppy water less than a mile from the marina, it did it again. This time, I was certain that no one touched the throttle. It raised up by about 300 RPM, I felt the immediate acceleration, the turbo spooled up like usual, and etc. Confused, I backed down off of the throttle (figured maybe I did something). When I backed her off, she dropped below 1350. A few minutes later, the same thing happened again. This time I left the throttle alone. The engine returned back to 1350 on its own after a few seconds.
Given the fact that there was an associated thrust, it sounded like it was a loaded-increase (the engine was under load when the increase occured), and because it was such a large jump in engine speed ~ 300 RPM (give or take) I am ruling out the idea that the tranny is slipping, that I was seeing cavitation, and etc. The second time it happened actually caused my little girl (almost 2 years old, and still gaining her sea legs) to topple backward and yell at me thinking I was messing around with her (I have been known to do that, especially when we are in rough water and it is safe to do so).
Knowing what I know about diesels, the only thing that makes any sense to me is that the governor might be starting to give me fits. As I said, there was an immediate acceleration, so I don't think it was tranny slip. Plus, she is a trawler and the prop is pretty submerged, and with such a low speed (7 knots) she should not have cavitated. Even so, if there was cavitation or slippage, the governor droop should not have been as much as it was.
I am also kicking around the idea that perhaps something is loose and is pulling on the throttle cable just enough to cause it to happen, then flops back over (or some other odd event like this). As the wind was already blowing about 30 knots and the water was becoming more of a bear (especially with the waves coming right at my starboard side) to deal with, and with that squall line moving in out in the distance, I wasn't going to monkey around out in the middle of the water to find out what was going on, and decided to head in and just take refuge. Good thing too because when the storm hit it was blowing 70 - 80 knots.
Has anyone out there with a 6354 Perkins (or any other engine for that matter) ever seen this before? If so, what was the diagnosis. Thanks!
I would consider myself to be a diesel engine expert, but this one really has me completely baffled and I am wondering if anyone has ever heard of this happening.
Over the weekend my family and I had our 34' Mainship trawler out. She has a 6354 Perkins 200 Hp diesel with a BW transmission.
On Saturday, we were moving along at 7 knots (1350 RPM) when all of a sudden the engine increased in speed all by itself, and then dropped back down to 1350. I had initially figured that one of the kids had been messing with the throttle, and I gave my usual speech about not touching things.
Then yesterday while in some fairly choppy water less than a mile from the marina, it did it again. This time, I was certain that no one touched the throttle. It raised up by about 300 RPM, I felt the immediate acceleration, the turbo spooled up like usual, and etc. Confused, I backed down off of the throttle (figured maybe I did something). When I backed her off, she dropped below 1350. A few minutes later, the same thing happened again. This time I left the throttle alone. The engine returned back to 1350 on its own after a few seconds.
Given the fact that there was an associated thrust, it sounded like it was a loaded-increase (the engine was under load when the increase occured), and because it was such a large jump in engine speed ~ 300 RPM (give or take) I am ruling out the idea that the tranny is slipping, that I was seeing cavitation, and etc. The second time it happened actually caused my little girl (almost 2 years old, and still gaining her sea legs) to topple backward and yell at me thinking I was messing around with her (I have been known to do that, especially when we are in rough water and it is safe to do so).
Knowing what I know about diesels, the only thing that makes any sense to me is that the governor might be starting to give me fits. As I said, there was an immediate acceleration, so I don't think it was tranny slip. Plus, she is a trawler and the prop is pretty submerged, and with such a low speed (7 knots) she should not have cavitated. Even so, if there was cavitation or slippage, the governor droop should not have been as much as it was.
I am also kicking around the idea that perhaps something is loose and is pulling on the throttle cable just enough to cause it to happen, then flops back over (or some other odd event like this). As the wind was already blowing about 30 knots and the water was becoming more of a bear (especially with the waves coming right at my starboard side) to deal with, and with that squall line moving in out in the distance, I wasn't going to monkey around out in the middle of the water to find out what was going on, and decided to head in and just take refuge. Good thing too because when the storm hit it was blowing 70 - 80 knots.
Has anyone out there with a 6354 Perkins (or any other engine for that matter) ever seen this before? If so, what was the diagnosis. Thanks!
