The curse continues... Brand new coupler slipping?
09-25-2016, 03:59 PM
#21
Platinum Member
Platinum MemberThread Starter
iTrader: (2)
About half the time, it is best to buy the OEM parts because buying cheaper parts never works out being cheaper for the end results. CHINA crap. Also there is no quality checks on a lot of aftermarket parts. NONE especially for the marine side of things. Not trashing Sierra because some of there stuff is good and some of there is complete junk.
The number 1 problem with trashing a coupler in very short order when everything else is in 100 percent order - read the SB completely to make sure you are correct with the set you have. Also we have seen some Sierra couplers not holding up.
read this to a Tee. And even applies if your engine alignment is dead on -
http://www.marinemechanic.com/merc/d...her-design.pdf
Also make sure the person installing the coupler did not warp it. More common than you think. Also Merc has a SB that helps installing the coupler properly and this also helps with alignment. Highly recommend a OEM service manual that is specific to all your boat / engine / drive applications. This will give you properly procedures and correct torque specs along with correct part installs.
The number 1 problem with trashing a coupler in very short order when everything else is in 100 percent order - read the SB completely to make sure you are correct with the set you have. Also we have seen some Sierra couplers not holding up.
read this to a Tee. And even applies if your engine alignment is dead on -
http://www.marinemechanic.com/merc/d...her-design.pdf
Also make sure the person installing the coupler did not warp it. More common than you think. Also Merc has a SB that helps installing the coupler properly and this also helps with alignment. Highly recommend a OEM service manual that is specific to all your boat / engine / drive applications. This will give you properly procedures and correct torque specs along with correct part installs.
Is it necessary to change the mounting system? This set-up (fiber washer and spring washer) has been in place and working on thousands of boats for years. Hell, my coupler was still working well when the transom and stringers were discovered to be shot. And I had ten hours on the boat this summer when the backfire killed the flywheel requiring replacement. Had the backfire not happened, I don't think the coupler would have went (it went because of my mistake).
Here's how I changed the coupler:
- got the engine ready to lift.
- lifted the engine using four points off my forklift.
- r-n-r'd rear cover and coupler. Coupler was torqued to spec in a star pattern.
- aligned engine using Mercury-made alignment tool checking it in 90-degree increments.
- alignment was perfect and the tool could be turned using my thumb and forefinger.
I've removed and replaced engines in at least four different boats without any troubles. Two have been Alphas; the other two, Bravos. This is the first time I've run into this much trouble.
09-26-2016, 10:33 AM
#25
Charter Member #1171
Charter Member
I do all my own work.
Is it necessary to change the mounting system? This set-up (fiber washer and spring washer) has been in place and working on thousands of boats for years. Hell, my coupler was still working well when the transom and stringers were discovered to be shot. And I had ten hours on the boat this summer when the backfire killed the flywheel requiring replacement. Had the backfire not happened, I don't think the coupler would have went (it went because of my mistake).
Here's how I changed the coupler:
- got the engine ready to lift.
- lifted the engine using four points off my forklift.
- r-n-r'd rear cover and coupler. Coupler was torqued to spec in a star pattern.
- aligned engine using Mercury-made alignment tool checking it in 90-degree increments.
- alignment was perfect and the tool could be turned using my thumb and forefinger.
I've removed and replaced engines in at least four different boats without any troubles. Two have been Alphas; the other two, Bravos. This is the first time I've run into this much trouble.
Is it necessary to change the mounting system? This set-up (fiber washer and spring washer) has been in place and working on thousands of boats for years. Hell, my coupler was still working well when the transom and stringers were discovered to be shot. And I had ten hours on the boat this summer when the backfire killed the flywheel requiring replacement. Had the backfire not happened, I don't think the coupler would have went (it went because of my mistake).
Here's how I changed the coupler:
- got the engine ready to lift.
- lifted the engine using four points off my forklift.
- r-n-r'd rear cover and coupler. Coupler was torqued to spec in a star pattern.
- aligned engine using Mercury-made alignment tool checking it in 90-degree increments.
- alignment was perfect and the tool could be turned using my thumb and forefinger.
I've removed and replaced engines in at least four different boats without any troubles. Two have been Alphas; the other two, Bravos. This is the first time I've run into this much trouble.
Could turn the tool,,,,,but how hard was it to insert and remove?
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I want to live in a world where a chicken can cross the road and not have its motives questioned.
09-26-2016, 10:41 AM
#26
Platinum Member
Platinum MemberThread Starter
iTrader: (2)
The tool went in with no resistance.
We started with the front mounts bottomed out, and the rear bolts in position and snug. We raised the front of the engine with the fork lift until we were able to get the tool to slide in with little resistance. We fine tuned from there. Once we were satisfied with how it felt, we tightened everything down.
We really thought we had it done properly. It was one of the cleanest alignment jobs I had done, and I was absolutely heartbroken when it failed... ten minutes from the ramp.
We started with the front mounts bottomed out, and the rear bolts in position and snug. We raised the front of the engine with the fork lift until we were able to get the tool to slide in with little resistance. We fine tuned from there. Once we were satisfied with how it felt, we tightened everything down.
We really thought we had it done properly. It was one of the cleanest alignment jobs I had done, and I was absolutely heartbroken when it failed... ten minutes from the ramp.
09-26-2016, 08:35 PM
#27
When the rear mounts sag in order to get the alignment tool to insert properly you will lower the front mounts ( the gimbal bearing pivots " angles " down) This forces the u Joint end of the shaft up inside the helmet and that forces the U joint out of alignment with the input shaft to the drive. This side loads the U joint and forces the coupler to side load. Mercruiser has an adapter to their tool that is used on TRS drives that slides onto the shaft and inserts into the helmet. IF the alignment is off the adapter WONT insert properly. This tool has worked for me every time.
I am running 800+ HP through a stock 1992 coupler. It uses to be on my SCARAB 34 behind 650 HP.
I don't want to get flamed here. What I say is fact and it works EVER TIME.
I am running 800+ HP through a stock 1992 coupler. It uses to be on my SCARAB 34 behind 650 HP.
I don't want to get flamed here. What I say is fact and it works EVER TIME.
09-27-2016, 11:40 AM
#28
Registered
Tom,
I am running the same coupler on my build and had some concerns with it being a Sierra but I have not had an issue. As far as the alignment goes, when I aligned my engine, I put a copious amount of grease of the end that slides in the coupler. I then insert lubed tool straight in and back out without rotating. I then inspect the grooves left in the grease from the splines on the coupler to see if the contact pattern is even all the way around. Is this how yours was completed? Is the new coupler centered on the flywheel? Is the flywheel true to the engine/crank? It looks like something was in a bind due to the rotational twist in there. I would assume your gimbal housing and all is in good order? This is going to be a difficult one to pinpoint as there is quite a few causes. Let's hope it was a defective coupler. Keep me posted buddy, I am sorry to hear about your troubles.
I am running the same coupler on my build and had some concerns with it being a Sierra but I have not had an issue. As far as the alignment goes, when I aligned my engine, I put a copious amount of grease of the end that slides in the coupler. I then insert lubed tool straight in and back out without rotating. I then inspect the grooves left in the grease from the splines on the coupler to see if the contact pattern is even all the way around. Is this how yours was completed? Is the new coupler centered on the flywheel? Is the flywheel true to the engine/crank? It looks like something was in a bind due to the rotational twist in there. I would assume your gimbal housing and all is in good order? This is going to be a difficult one to pinpoint as there is quite a few causes. Let's hope it was a defective coupler. Keep me posted buddy, I am sorry to hear about your troubles.
