Alpha one gen II growling noise when turning

[TripleEh]

Hi folks. New to the forum. Engineer by profession but lots of practical experience in on cars. I’ve been reading these forums for a while and learning lots but haven’t been able to solve my particular problem. 1999 crownline 4.3 efi with the factory Alpha one drive #0L465387. Unsure of the hours but it’s a very clean boat. I’m the third owner. The boat makes a growling noise when turning along with a slight vibration. It gets worse the further you turn and does not change at all with trim (only with steer). It also seems to have a slight knocking sound at idle and a slight vibration below 2k rpm. First thing I did was try a different prop. No change. I had a marine mechanic change the gimbal and ujoints without any luck. When I came back he put a second gimbal in and no change. He also inspected the bevel gears and said they looked fine. After that, I bought tools myself and put a quicksilver gimbal bearing in, changed the long yoke, and put another set of ujoints in. The growl persists. Smooth without noise in a straight line but growling on turns, especially when pulling tubers. After that, I retorqued the gimbal ring bolts to 55 and the hinge pins to 100 and replaced the hinge pin washers to tighten up the side to side movement. Still no change. I have checked alignment many times and the tool slides in very smoothly. Tonight I removed the drive one more time and for the first time ever I noticed the alignment tool “caught” slightly on the coupler but still slid in very easily. I have not tried rotating the engine and performing multiple alignment checks yet. My thoughts are:
1. Maybe bad coupler? (but the splines are well lubed and very square on both the coupler and yoke)
2. Gimbal not seated? It has had 3 new gimbals but perhaps there is scoring preventing it from being seated.
3. Something wrong with the replacement ujoints (both times) leaving the shaft out of balance or out of phase.
4. Something innternal to the drive (but why would it only happen on corners)

Wondering what wisdom you can share for my problem folks. Thanks in advance.

 

[Rick Stephens]

Bent drive shaft maybe?
Wrong u-joints?
Yoke crooked?
Coupler no longer centered/straight?
Coupler to flywheel?

 

[TripleEh]

Bent drive shaft maybe?
Wrong u-joints?
Yoke crooked?
Coupler no longer centered/straight?
Coupler to flywheel?

Thanks Rick. I will check the drive shaft runout. U joints were Sierra, ordered from a dealer by drive serial and were replaced twice by two different people. Not positive how to check the coupler but I will start by turning it over with the drive off.

 

[Rick Stephens]

Stick a 1" pipe in the coupler with the drive off and spin the motor.

 

[Searay205]

Does the vibration occur at all rpm when turning?

 

[TripleEh]

Does the vibration occur at all rpm when turning?

Yes, at all rpm. More growling noise than vibration but yes.

 

[tpenfield]

Drive shaft bearing
Coupler

 

[Eric 3.7LX Alpha 1]

Drive shaft bearing
Coupler

That's a good guess there.

 

[TripleEh]

Drive shaft bearing
Coupler

Thanks for these….assuming you mean the lower, horizontal shaft. I will check it. One other characteristic of this noise - if I’m at idle in gear, turn the wheel and apply power, the noise is there. If the drive is straight -no noise. Not sure that bearing knows which way the prop is pointing in this case leading me to believe it’s still in the top end. Nevertheless I will check.

 

[Scott06]

Thanks for these….assuming you mean the lower, horizontal shaft. I will check it. One other characteristic of this noise - if I’m at idle in gear, turn the wheel and apply power, the noise is there. If the drive is straight -no noise. Not sure that bearing knows which way the prop is pointing in this case leading me to believe it’s still in the top end. Nevertheless I will check.

I think he meant the input shaft bearing in drive, but could be bearings on vertical driveshaft. Would think the input yoke and bearing would have some side play if worn and be the only part to make noise when turning drive. I think you only need the tool to remove large ring nut off drive input shaft to check this bearing out. If you replace you need to set rolling torque and need a in lb torque wrench. capable of really low <10 in lbs torque readings

 

[TripleEh]

I think he meant the input shaft bearing in drive, but could be bearings on vertical driveshaft. Would think the input yoke and bearing would have some side play if worn and be the only part to make noise when turning drive. I think you only need the tool to remove large ring nut off drive input shaft to check this bearing out. If you replace you need to set rolling torque and need a in lb torque wrench. capable of really low <10 in lbs torque readings

Got it. I’ve been scared to pull that one out so far but I guess if I don’t touch the bearing nut I can remove and inspect with just the castle nut without affecting anything. Thanks.

 

[Scott06]

Got it. I’ve been scared to pull that one out so far but I guess if I don’t touch the bearing nut I can remove and inspect with just the castle nut without affecting anything. Thanks.

Check out this video gives an idea of what comes out

this Chris is a moderator here and has excellent videos all worth watching

Would think you can pop it out and feel for roughness. I assume yours has a drive lube monitor so it wouldn't run dry if input shaft seal leaks

 

[TripleEh]

Check out this video gives an idea of what comes out

this Chris is a moderator here and has excellent videos all worth watching

Would think you can pop it out and feel for roughness. I assume yours has a drive lube monitor so it wouldn't run dry if input shaft seal leaks

I will try that. I’ve also heard that 1.62 gears have match marks so I will check for that before and after I pull. Thanks

 

[Scott06]

I will try that. I’ve also heard that 1.62 gears have match marks so I will check for that before and after I pull. Thanks

that I do not know maybe @achris does . He may also have some ideas on your noise as I would expect a gimbal and u joint replacement to take care of it

 

[TripleEh]

I took a look at this today. I’m still waiting on the castle nut wrench to arrive so I focused on the coupler and alignment instead of checking the drive shaft bearing. I found that one front motor mount was adjusted lower than the other but a fair bit which I imagine may put a twist in the engine. I gauged this by counting threads so I hope the boat is square. I adjusted the front mounts until the alignment tool slid in without “catching” on the coupler. It doesn’t seem to slide much more easily than before but it doesn’t hang up when going in the front edge coupler. I also found the set screw to be loose on the shift lever arm in the bell housing so I tightened that up a number of turns. On muffs things sound good at all steering angles. Will test in the water tomorrow

 

[TripleEh]

I took a look at this today. I’m still waiting on the castle nut wrench to arrive so I focused on the coupler and alignment instead of checking the drive shaft bearing. I found that one front motor mount was adjusted lower than the other but a fair bit which I imagine may put a twist in the engine. I gauged this by counting threads so I hope the boat is square. I adjusted the front mounts until the alignment tool slid in without “catching” on the coupler. It doesn’t seem to slide much more easily than before but it doesn’t hang up when going in the front edge coupler. I also found the set screw to be loose on the shift lever arm in the bell housing so I tightened that up a number of turns. On muffs things sound good at all steering angles. Will test in the water tomorrow

In the water today and it’s no better. When my tool arrives I’ll check the drive shaft bearing. Otherwise I’m leaning toward a bad coupler. I didn’t have 1” round bar at home so I used a piece of thin wall tube to check the coupler. Unfortunately I don’t think the tube is very true but it does look pretty bad.

 

[Rick Stephens]

I took a look at this today. I’m still waiting on the castle nut wrench to arrive so I focused on the coupler and alignment instead of checking the drive shaft bearing. I found that one front motor mount was adjusted lower than the other but a fair bit which I imagine may put a twist in the engine. I gauged this by counting threads so I hope the boat is square. I adjusted the front mounts until the alignment tool slid in without “catching” on the coupler. It doesn’t seem to slide much more easily than before but it doesn’t hang up when going in the front edge coupler. I also found the set screw to be loose on the shift lever arm in the bell housing so I tightened that up a number of turns. On muffs things sound good at all steering angles. Will test in the water tomorrow

One of the tricks is to loosen the mount adjusting bolts until on both sides, with the motor suspended from the front lifting bracket - that bracket is there just for this purpose. Then adjust both sides until they have equal pressure. Last time I did this was able to suspend the motor off a 2 x 4 across the boat.

 

[TripleEh]

Below is a link to a coupler test with an aluminum bar. The tolerance is +\- 0.012” on the bar so it’s not the tightest fit in the coupler. In any case it seems to wobble quite a bit. Does this look normal to you guys? Would the flex in the rubber make up for this set or would this cause vibration and noise? Next step is to check the alignment at four different engine rotations.

 

[tank1949]

Hi folks. New to the forum. Engineer by profession but lots of practical experience in on cars. I’ve been reading these forums for a while and learning lots but haven’t been able to solve my particular problem. 1999 crownline 4.3 efi with the factory Alpha one drive #0L465387. Unsure of the hours but it’s a very clean boat. I’m the third owner. The boat makes a growling noise when turning along with a slight vibration. It gets worse the further you turn and does not change at all with trim (only with steer). It also seems to have a slight knocking sound at idle and a slight vibration below 2k rpm. First thing I did was try a different prop. No change. I had a marine mechanic change the gimbal and ujoints without any luck. When I came back he put a second gimbal in and no change. He also inspected the bevel gears and said they looked fine. After that, I bought tools myself and put a quicksilver gimbal bearing in, changed the long yoke, and put another set of ujoints in. The growl persists. Smooth without noise in a straight line but growling on turns, especially when pulling tubers. After that, I retorqued the gimbal ring bolts to 55 and the hinge pins to 100 and replaced the hinge pin washers to tighten up the side to side movement. Still no change. I have checked alignment many times and the tool slides in very smoothly. Tonight I removed the drive one more time and for the first time ever I noticed the alignment tool “caught” slightly on the coupler but still slid in very easily. I have not tried rotating the engine and performing multiple alignment checks yet. My thoughts are:
1. Maybe bad coupler? (but the splines are well lubed and very square on both the coupler and yoke)
2. Gimbal not seated? It has had 3 new gimbals but perhaps there is scoring preventing it from being seated.
3. Something wrong with the replacement ujoints (both times) leaving the shaft out of balance or out of phase.
4. Something innternal to the drive (but why would it only happen on corners)

Wondering what wisdom you can share for my problem folks. Thanks in advance.

That's an old boat. I suspect many things possibly wrong. With it in water and running and looking at drive shaft, does shaft wobble? Some shafts you can see. Some U can't. Or feel the back of motor/transom assembly for vibrations. Does it wobble more when turning with drive torquing? If you have examined u joints and gimbal for no slop, then I fear mounts or transom is flexing. Put 2x6 across boat so that you can attach a coffin hoist to motor's center lifting lug and try to raise front of motor. You may have to build some sort of lifting lug. If you notice flexing in mount, you will have to repair. Good luck.

 

[TripleEh]

That's an old boat. I suspect many things possibly wrong. With it in water and running and looking at drive shaft, does shaft wobble? Some shafts you can see. Some U can't. Or feel the back of motor/transom assembly for vibrations. Does it wobble more when turning with drive torquing? If you have examined u joints and gimbal for no slop, then I fear mounts or transom is flexing. Put 2x6 across boat so that you can attach a coffin hoist to motor's center lifting lug and try to raise front of motor. You may have to build some sort of lifting lug. If you notice flexing in mount, you will have to repair. Good luck.

Thanks for the tip. I’ll watch the coupler in the water. I can definitely see the coupler and I may be able to see the shaft. With the overall condition of the boat I’m confident in the structure.