I have a 1978 Hunter 27 powered by a Yanmar diesel. The boat appears to be losing power through the propellor. My speed has dropped below 5 knots. The engine runs fine and I replaced the head and checked the compression rings. Also, I have completed the following: cleaned the prop, checked the compresson, set the valves, pop tested the injector, added new fuel and additive. The cutlass bearing has some play in it and I plan to have it changed when the boat is hauled. Have I missed something in the engine? Does the transmission have clutches that need adjustment? If so how is this done? How long between transmission oil changes? Has anyone experienced this problem? Thanks for the help.
Loss of speed
- Thread starter Calvin1Calvin
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What's the condition
of your bottom? In this area (Chesapeake) it is quite common for boats to "slow down" toward the end of our season as many may be carrying a lot of extra growth on the bottom. A short haul and power wash may be what your boat needs. You, or a diver, may want to take a look before blaming your lost speed on the engine.
of your bottom? In this area (Chesapeake) it is quite common for boats to "slow down" toward the end of our season as many may be carrying a lot of extra growth on the bottom. A short haul and power wash may be what your boat needs. You, or a diver, may want to take a look before blaming your lost speed on the engine.
I agree...
This sounds like barnacle growth on your prop. Or maybe weed growth on the hull. Heavy barnacle growth happened to a friend of mine who didn't use his boat enough this season. A quick haul and powerwash solved the problem. Andy
This sounds like barnacle growth on your prop. Or maybe weed growth on the hull. Heavy barnacle growth happened to a friend of mine who didn't use his boat enough this season. A quick haul and powerwash solved the problem. Andy
There are some barnacles on the hull and rudder not many. The prop and shaft were cleaned two months ago and again Monday. I have not used the boat since Sunday, October 8, 2006. The boat was hauled, sanded and new bottom paint applied approximately 2-3 yrs ago. It is due for a bottom job. Our water is not that salty and 3-5 yrs between bottom jobs is normal. I still have the original 2 bladed Federal prop that was standard on the boat and it is in good condition. I use the boat every weekend.
Servo clutch
You may be ready for the servo clutch in the tranny to be replaced. If this did not suddenly occur and has been slowly getting worse I would bet thats what it is. If you do not notice the same loss of power in reverse and if you can feel the clutch grab a little more with increased rpm in forward you know it's the clutch. The gearbox on the 1gm is pretty simple, when you break it down and inspect the clutch don't be surprised if it looks like it's not worn out. The tapered ends of the clutch lock into the forward and reverse gears and if you drop the reverse end of the clutch into the forward gear while you have it on the bench and more of the shoulder shows the clutch is worn out. Watch your shift cable adjustment when you re install the gearbox so that the shift lever is not loaded when in either forward or reverse. Good luck.
You may be ready for the servo clutch in the tranny to be replaced. If this did not suddenly occur and has been slowly getting worse I would bet thats what it is. If you do not notice the same loss of power in reverse and if you can feel the clutch grab a little more with increased rpm in forward you know it's the clutch. The gearbox on the 1gm is pretty simple, when you break it down and inspect the clutch don't be surprised if it looks like it's not worn out. The tapered ends of the clutch lock into the forward and reverse gears and if you drop the reverse end of the clutch into the forward gear while you have it on the bench and more of the shoulder shows the clutch is worn out. Watch your shift cable adjustment when you re install the gearbox so that the shift lever is not loaded when in either forward or reverse. Good luck.
The prop and shaft were cleaned, there are some barnacles on the rudder and a few on the bottom. The boat was pulled and a bottom job done approximately 2-3 yrs ago which is common for our area. Very few barnacle problems where the boat is docked. The mixing elbow was changed last year and the exhaust ports on the engine were cleaned. The boat requires a small amount of throttle in reverse and a large amount when in forward. There appears to be a minimal slowing of boat speed in the last two months which leads me to think I need to look at the clutch in the transmission. I am trying to cover all bases before I pull the engine.
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