jakwi
Petty Officer 2nd Class
- Joined
- Jan 7, 2019
- Messages
- 184
Hi all I have a 357 alpha 4v Mercruiser repower mated up to a Alpha 1 gen 2. We are down in the florida keys this week and ran about 40 miles up the gulf side from Marathon to Islamorada and then 6 miles out to alligator reef.
I run a 19p prop , and I have a spare 17 that I sometimes use if we are heavily loaded as it gets us up a plane a bit easier, but I believe the 19 is the correct prop for my setup, 24ft cabin cruiser.
Anyway on the run up on the gulf side everything was running great, about 4000rpm there was one moment when we touched the sand while up on plane but it happened so quickly that I wasn't able to trim up or anything. It was subtle enough that none of my family even noticed it happened.
We carried on with no apparent issues went out the inlet still on plane and then out to the reef. It was a little choppy 3ft(1m) waves at 5s, so we were taking a beating. My avg speed dropped from 26 down to maybe 22 or 23, but I figured it was just the sea state I had to pus the RPM up to 4600 to keep it on plane.
Got out there, and while it was beautiful it was really to rough to enjoy and everyone was starting to feel squishy so we decided to head back.
When I tried to get up on plane it would seem to work and then at about 3000 rpm revs would jump up and propulsion would cease, I tried a couple of times and ended up trolling back at about 2500 rpm. I had the spare 17 inch prop with me so we found a shallow spot and swapped it out, I figured I'd cracked the prop hub. No big deal it happens. I put the 17 on and all was good, jumped right up on plane and ran fine. About half way back Maybe 20 miles on the return leg we are up on plane in 8ft of water 25mph, no chop and suddenly it happens again, It hits the rev limiter. I come off plane let it sit try again, no go, and look at a few things, try again and good to go. Ran 20 more miles back to the house, and no further issues. I cycled between slow and high speeds twice after this with no further issues.
This morning I pulled the hub out of the 19 and it looks perfect, no cracks, everything is fine. So the only thing I can think is engine coupler. It is weird though. The engine is a 2007 with probably no more than 150 hours on it. 99% of my running is in the intercoastal or St johns river, so no more chop than what comes up from other boats wakes.
I pull the drive every year, change the oil, inspect bellows and seals. I changed the gimbal bearing last year as a precaution, but honestly I think it was ok. I have an alignment tool that I use to reinstall and can spin it with two fingers when I'm done. My engine mounts and stringers are rock solid.
So Why would my coupler fail? Is it standard practice to change it with the repower? It was repowered by the PO, so I don't know if the coupler is original or not, if it's original the boat is a 2003. Aren't they supposed to be lifetime? Could it be anything else? How hard is it to change the coupler, and there seem to be two styles, how do I know which one I have before tearing everything apart?
Ok, sorry for the wall of text and 20 questions, and thanks for the guidance.
I run a 19p prop , and I have a spare 17 that I sometimes use if we are heavily loaded as it gets us up a plane a bit easier, but I believe the 19 is the correct prop for my setup, 24ft cabin cruiser.
Anyway on the run up on the gulf side everything was running great, about 4000rpm there was one moment when we touched the sand while up on plane but it happened so quickly that I wasn't able to trim up or anything. It was subtle enough that none of my family even noticed it happened.
We carried on with no apparent issues went out the inlet still on plane and then out to the reef. It was a little choppy 3ft(1m) waves at 5s, so we were taking a beating. My avg speed dropped from 26 down to maybe 22 or 23, but I figured it was just the sea state I had to pus the RPM up to 4600 to keep it on plane.
Got out there, and while it was beautiful it was really to rough to enjoy and everyone was starting to feel squishy so we decided to head back.
When I tried to get up on plane it would seem to work and then at about 3000 rpm revs would jump up and propulsion would cease, I tried a couple of times and ended up trolling back at about 2500 rpm. I had the spare 17 inch prop with me so we found a shallow spot and swapped it out, I figured I'd cracked the prop hub. No big deal it happens. I put the 17 on and all was good, jumped right up on plane and ran fine. About half way back Maybe 20 miles on the return leg we are up on plane in 8ft of water 25mph, no chop and suddenly it happens again, It hits the rev limiter. I come off plane let it sit try again, no go, and look at a few things, try again and good to go. Ran 20 more miles back to the house, and no further issues. I cycled between slow and high speeds twice after this with no further issues.
This morning I pulled the hub out of the 19 and it looks perfect, no cracks, everything is fine. So the only thing I can think is engine coupler. It is weird though. The engine is a 2007 with probably no more than 150 hours on it. 99% of my running is in the intercoastal or St johns river, so no more chop than what comes up from other boats wakes.
I pull the drive every year, change the oil, inspect bellows and seals. I changed the gimbal bearing last year as a precaution, but honestly I think it was ok. I have an alignment tool that I use to reinstall and can spin it with two fingers when I'm done. My engine mounts and stringers are rock solid.
So Why would my coupler fail? Is it standard practice to change it with the repower? It was repowered by the PO, so I don't know if the coupler is original or not, if it's original the boat is a 2003. Aren't they supposed to be lifetime? Could it be anything else? How hard is it to change the coupler, and there seem to be two styles, how do I know which one I have before tearing everything apart?
Ok, sorry for the wall of text and 20 questions, and thanks for the guidance.
