"Sluggish" port engine shaft

[Superg]

When my boat was last laid up, I noticed that the port side shaft had a LOT more resistance to rotate than the starboard shaft, which rotated quite freely and easily (and without vibration or lateral movement by the way). Ok, but could be because laid up on stilts, the boat changes shape, puts pressure on shaft bearings, etc.

So now with my boat in water, the same thing. Rotating the port shaft faces VERY noticeable resistance => engine must do more work to turn it. Starboard shaft rotates freely and efficiently.

I was hoping this was just an issue with the cutlass bearing, but I know that was optimistic thinking. I really think the truth is that the resistance is coming from inside the port engine itself. Any thoughts? Hate to have to have this engine pulled out when the boat otherwise seems to run well. But I know that resistance must have an effect that the engine has to overcome.

270 Crusaders.

[bud37]

Have your engine/shaft alignment checked or read up and do it yourself if mechanically inclined ....could just be that simple but you will have to check it anyway to cross off other issues if they are there. Things move around over time, if it turns out to be out of alignment have a good look at the engine bed stringer/stringers in that area.

Could be bearing/shaft alignment as well.....what makes you think the bearing is ok ?

[km1125]

My guess is that unless it takes a wrench to turn that shaft, the engine isn't going to really notice it.

You could have a few things going on. There could be an alignment issue which is causing some binding. You could disconnect the coupling and check that, and while it's apart compare how each shaft turns (which would just have the stuffing box and cutlass as culprits). If the those are ruled out and you address any alignment issues, you could easily have differences within the reduction gears or transmission. You could have some freeplay in one and some bearing load in the other, or you could have some minor warping on some clutch plates. If it's the forward clutch plates that are warped, then that's not an issue at all once you're in gear, as those plates are locked together.

[plittle2005]

As km1125 notes, it could be misalignment, shaft problem or transmission. But something is definitely binding. They should rotate freely by hand for normal operation.

It is not due to blocking on land.

You have 3 parts in your drive train: trans, stern tube/stuffing box and cutless. Each can be checked separately. You must unbolt the flange at the trans.

If the trans-side flange rotates freely, it is good. This can be checked in the water. But if hard to turn, then a problem is developing within the trans and must be corrected by pulling and rebuilding.

But if the shaft itself is binding, then a short-haul is required to loosen the stuffing box gland and check the cutless and strut alignment.

If loosening the stuffing box reduces rotating resistance, then best to pull the prop and shaft out to check shaft seal surface condition and straightness and to replace the packing.

The cutless will be worn more or less, but if any detectable sidewise slop, it should be replaced. Easy to do at this point. (Good time to do the other cutless as well. This can be done shaft-in if the yard has the special puller. Most do.)

Methodical inspection will find the problem. I think serious problems could result from this condition, so you are right to address them now.

[bud37]

Ya the engine is not the problem IMO.....if it was it would not be quiet and smooth running. Actually another question.....how long after the boat was put back in the water did you check again.....it may take a good 24 hours to settle sometimes.

[Superg]

I checked mid season.. So definitely not hull flexion.
Well, I put it in a work order for the marina service department to address over the winter. I asked them to check and probably replace all the shaft bearings first, and if the issue is still there to look farther up the powertrain.

[plittle2005]

To reiterate the above, a warning: Something is wrong with your driveline, it could really be disabling while on the water.

Checking is simple: remove the 4 flange bolts at the transmission.

1. If the transmission flange turns hard, you've got a trans problem which will require removal and rebuilding. If let go, it would thoroughly trash the trans. Big $$!

2. If the shaft turns hard, you've got a bad stuffing gland seal or some other shaft alignment problem. The gland could fail and sink the boat.

Bottom line, you need to find out now, don't keep running until maybe big disaster!