My 3GM30F had a similar issue. Kanzaki transmission. I can only assume that you did the alignment procedure correctly which is kind of a big assumption. It's not super easy. After eliminating all other possibilities and exhaustive research I learned that the transmission is known for hammering when the clutch slips. In my case, it only did it in forward gear and it was much worse when the boat was actually moving through the water as opposed to running in the slip. My suggestion is to eliminate everything else: alignment, shaft straightness, etc and then look at a transmission rebuild.
yanmar 1gm10 engine and shaft alignment
- Thread starter John6275
- Start date
Made it back to the boat today. Tried some more adjustments as well as many suggestions I received here. Shaft seems to turn freely by hand. Engine runs well and smooth when not in fear.
When shaft was disconnected it was very smooth and placed in gear.
After adjustments I did notice a bit of a difference but still thumping.
Discovered If I put forward pressure on the engine when running and it is it in forward gear it smooths out. Unfortunately there are no adjustments that I'm aware of to move the engine forward.
Hoping someone might know what the problem could be and possibly a solution.
Thanks
When shaft was disconnected it was very smooth and placed in gear.
After adjustments I did notice a bit of a difference but still thumping.
Discovered If I put forward pressure on the engine when running and it is it in forward gear it smooths out. Unfortunately there are no adjustments that I'm aware of to move the engine forward.
Hoping someone might know what the problem could be and possibly a solution.
Thanks
The engine is adjustable in both the horizontal as well as the vertical plain. There will be (or better be) slots in the base of the mount which will allow for fore and aft movement.
You're exactly right (and I'm exactly wrong) about the fore/aft adjustment on the mounts. See this on a photo I pulled up. Fortunately I have not played with this adjustment for some time. Alignment checks have been good for many years.
Time to take the coupling apart and see how far back the shaft will slide and does it hit anything ? I would think you would be able to feel some contact at some point.
We're talking far out desperate measures for a desperate situation
.
Can't remember if you've inspected the underside of the boat while in the water. Any chance you've got a loose zinc which is rubbing against the strut ? From what you've described about the thumping noise, I don't think you want to run it for too long for fear of slowly eroding something to the point of destruction.
Time to take the coupling apart and see how far back the shaft will slide and does it hit anything ? I would think you would be able to feel some contact at some point.
We're talking far out desperate measures for a desperate situation
.
Well, I'll take a peak but going to get a little warmer here. 35 degree nights haven't helped water temp in addition to poor visibility in the lake. However, I will be check that. Mean while hoping someone else has an idea since I can't hall her out.You're exactly right (and I'm exactly wrong) about the fore/aft adjustment on the mounts. See this on a photo I pulled up. Fortunately I have not played with this adjustment for some time. Alignment checks have been good for many years.
Can't remember if you've inspected the underside of the boat while in the water. Any chance you've got a loose zinc which is rubbing against the strut ? From what you've described about the thumping noise, I don't think you want to run it for too long for fear of slowly eroding something to the point of destruction.
Time to take the coupling apart and see how far back the shaft will slide and does it hit anything ? I would think you would be able to feel some contact at some point.
We're talking far out desperate measures for a desperate situation
I actually didn't put shaft in. PO supposedly had shaft trued and he put it in and aligned and cutlass etc.
Not sure what you mean by forward pressure. It sounds like it way very well be a slipping clutch. Are you able to do the same thing while it is in reverse? What transmission is it? Kanzaki?
I'd be a little suspicious of the "trued" shaft. When the shaft in my boat got bent by wrapping a dock line, the shop said they could straighten it but could not guarantee it would stay straight. They recommended replacing it, which I did. Wasn't that much more expensive than attempting to straighten it.
what was the cost ? I haven't checked that yet plus believe it or not there is no easy way locally to haul this type and size boat out on the lake.
Update
Finally ended up getting a marine mechanic involved.
He checked shaft alignment and engine mounts and all look good. The prop was pulled and it and key and end of shaft were inspected and all looked good. While the prop was off the engine was ran in both gears. Everything was smooth. Alignment was checked with a straight edge against shaft and looked good. Strut and cutlass looked good and turned freely. This was with mechanic in boat and his diver in the water. Prop put back on and ran again and ran smoothly until a few gear changes and then it would start its knocking.
Mechanic is not sure unless it is transmission related.
This type of engine and sailboats not as common here so although he is a good mechanic and well thought of he is not sure. The other good thing , he is honest and not charging since he can't fix it. Thus someone I will take care of and hope between the two of us and some of you, we can get this fixed. So, looking for some guidance here.
Thanks
Finally ended up getting a marine mechanic involved.
He checked shaft alignment and engine mounts and all look good. The prop was pulled and it and key and end of shaft were inspected and all looked good. While the prop was off the engine was ran in both gears. Everything was smooth. Alignment was checked with a straight edge against shaft and looked good. Strut and cutlass looked good and turned freely. This was with mechanic in boat and his diver in the water. Prop put back on and ran again and ran smoothly until a few gear changes and then it would start its knocking.
Mechanic is not sure unless it is transmission related.
This type of engine and sailboats not as common here so although he is a good mechanic and well thought of he is not sure. The other good thing , he is honest and not charging since he can't fix it. Thus someone I will take care of and hope between the two of us and some of you, we can get this fixed. So, looking for some guidance here.
Thanks