dantheman
Member
Vibration (inboards)
I'm getting some vibration that happens around 3k rpm and up, it doesn't happen when driving slow. My previous boat, a 1984 33 Ft Chris had a similar vibration that was resolved by installing the spare props, So I jumped in the murky waters with Scuba and a gear puller, removed props, had them reconditioned, sadly, it didn't totaly fix the problem, I thought the boat seemed smoother at low speed and the vibration at 3k rpm and up only felt slightly better.
So I started poking around in the engine compartment and decided checking the alignment might be the next step. I put a dial indicator on the shafts near the packing nut and found the stbd shaft running out .005 and the port was out .008. Next I unbolted the couplers and found something I think is unusual. When using feeler gauges I found that both engine alignments are out an equal amount and it's a lot. The widest difference in gap was at the stbd side of each coupler and was .025. I took a number of measurements, I turned the shafts and trannies and still have the same gap at the stbd side of each coupler, I then indexed the shaft 180 degrees from the tranny and took measurements with same results.
One other thing that I did before unbolting the couplers was to pull on the shafts while watching the dial indicator and I could make the dial move, I don't recall exactly how much it moved but roughly .008 to .010.
At this point, I haven't done anything that could make things worse, I had a friend look at it, he basically told me how to gauge it with the feeler gauges. Then I got on the internet and read for hours about alignments. I know from what I read that it's a very tedious process, but from I see, it looks as though the engines need to move to the stbd to reduce the gaps.
To me it seems strange and almost makes sense at the same time that both engines would be out of alignment the same amount. They both turn in the same direction and it could be the setteling of the boat effected both engines equally, or maybe tourque has effected them the same, oh yeah, I put a wrench on the motor and tranny mounts and they were not too tight, they weren't loose, but it didn't take too much effort to break them loose.
So I scribed lines all around the motor mounts for a reference point, loosend the engine and tranny mounts, leaving the port side tranny mount a bit tighter, hoping that I could pivot on the port tranny bolt as the front of the engine moves to stbd. They say to use a heavy hammar to rap the motor mount and slide the engine over. This is where I'm stuck, I don't want to hammar a hole in the side of the block. I'm not too worried about making the alignment worse because I can hire someone if I mess up. I gave the motor mounts a few blows with the hammar (not too hard) and nothing happend. Maybe the mounts are at the end of their travel on the side that I haven't seen yet. But anyways, I was wondering if someone with more experience could comment on my findings. (straight through trannys) Thanks for reading this and I really value/appreciate your help. Dan
I'm getting some vibration that happens around 3k rpm and up, it doesn't happen when driving slow. My previous boat, a 1984 33 Ft Chris had a similar vibration that was resolved by installing the spare props, So I jumped in the murky waters with Scuba and a gear puller, removed props, had them reconditioned, sadly, it didn't totaly fix the problem, I thought the boat seemed smoother at low speed and the vibration at 3k rpm and up only felt slightly better.
So I started poking around in the engine compartment and decided checking the alignment might be the next step. I put a dial indicator on the shafts near the packing nut and found the stbd shaft running out .005 and the port was out .008. Next I unbolted the couplers and found something I think is unusual. When using feeler gauges I found that both engine alignments are out an equal amount and it's a lot. The widest difference in gap was at the stbd side of each coupler and was .025. I took a number of measurements, I turned the shafts and trannies and still have the same gap at the stbd side of each coupler, I then indexed the shaft 180 degrees from the tranny and took measurements with same results.
One other thing that I did before unbolting the couplers was to pull on the shafts while watching the dial indicator and I could make the dial move, I don't recall exactly how much it moved but roughly .008 to .010.
At this point, I haven't done anything that could make things worse, I had a friend look at it, he basically told me how to gauge it with the feeler gauges. Then I got on the internet and read for hours about alignments. I know from what I read that it's a very tedious process, but from I see, it looks as though the engines need to move to the stbd to reduce the gaps.
To me it seems strange and almost makes sense at the same time that both engines would be out of alignment the same amount. They both turn in the same direction and it could be the setteling of the boat effected both engines equally, or maybe tourque has effected them the same, oh yeah, I put a wrench on the motor and tranny mounts and they were not too tight, they weren't loose, but it didn't take too much effort to break them loose.
So I scribed lines all around the motor mounts for a reference point, loosend the engine and tranny mounts, leaving the port side tranny mount a bit tighter, hoping that I could pivot on the port tranny bolt as the front of the engine moves to stbd. They say to use a heavy hammar to rap the motor mount and slide the engine over. This is where I'm stuck, I don't want to hammar a hole in the side of the block. I'm not too worried about making the alignment worse because I can hire someone if I mess up. I gave the motor mounts a few blows with the hammar (not too hard) and nothing happend. Maybe the mounts are at the end of their travel on the side that I haven't seen yet. But anyways, I was wondering if someone with more experience could comment on my findings. (straight through trannys) Thanks for reading this and I really value/appreciate your help. Dan
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