whirring noise after transom/ u joint/ oil seal repair

[williemon]

Mercruiser V 6 alpha one gen 2. 2006 tahoe Q6.

I just got finished installing a new impeller, bellows kit, gimbal bearing, u joints, oil seal in upper drive shaft.

To replace the oil seal, I removed only the drive shaft (did not open top cover), removed the gear and bearings from the shaft yoke, installed the new seal and put it all together. The bearings were the press fit so I followed instructions to obtain a 5 inch pound rolling torque reading using a snap on brand torque gauge. The shims in the upper housing remained in the housing. I used a proper tool to tighten the castle nut, I stood on it to obtain roughly a 160 ft pound torque, then whacked it several times with a big hammer.

Everything else was replaced without issue. Engine was out of alignment but not too bad, so I aligned it. It was not a perfect alignment though but better than it was. I put the drive on, had a little resistance so I had to use my body weight and work it and it slowly slipped on. I finished the rest of the way by installing the nuts.

I ran it on the muffs and all sounded and looked good. The boat was lake tested a few days later. All went well for the 30 min test, but there at the end, the whirring sound had developed. I have since pulled the outdrive again. All looks good so far. I realigned engine much better this time. I rotated the engine in 90 degree increments and adjusted the front of engine down so the alignment tool slips in and out with one hand in 3 of the 4 quadrants. The 4th being just a little tighter.

I then reinstalled the drive just to test it on the muffs. I still heard the whirring noise at idle with outdrive trimmed down. Trimming up helps it to not be as loud, and it almost goes away. Its very loud with engine hatch open. Closed hatch allows it to be heard throughout the boat. At the back out side the boat, its not as loud. I tried to listen with a stethoscope but cant pinpoint it. Its louder at the bell-housing though. Turning the drive did not make a difference. The whirring goes up in pitch as engine rpm is increased. It sounds like a supercharger actually.

Any ideas what is the cause of this?

 

[Bt Doctur]

What tools did you use to seat the gimbal bearing and is it fully seated

 

[williemon]

I used the old bearing housing as a push ring and made a push rod out of a 2x4 and whacked it firmly a number of times untill it seemed properly seated. I took the time to make sure it did not **** one way or the other and it did make a different more solid sound once it was on in there so i believed it was seated. Putting my finger in there behind the bearing, it feels like just a hint of clearence between it and the transom housing just like the original felt. I installed it with the slots facing inward and the grease hole lineing up. I have greased it also. The splines on the driveshaft and what i could see in the coupler look real good.

 

[williemon]

I have worked with the alignment more. I raised one side of the engine a little bit. I also had to adjust the gimbal bearing more to better align it. Once done, the alignment bar did in fact slip in and back out with 3 fingers. Then when i reinstalled the drive for a test on the muffs, it slipped into place much easier than before. I fired it up and did not have that whirring like there was before. Is the bearing and alignment that sensitive on these boats? Seemed more sensitive than another one that i had worked on with a gen 1 alpha drive.

 

[williemon]

I finally got the gimbal set and the engine aligned so alignment bar goes in with two fingers and back out as well. Everything else looked good. Reinstalled drive and ran on muffs. No noises or whirring sound could be heard. Put it in the water, put it in gear and instantly the whirring noise was there and resonated throughout the boat. After running a few moments, the whirring noise is still there. It gets higher pitched with as rpm goes up. In neutral its not there. I did discover that turning the steering full lock will produce that noise as well. Then when i had the drive pretty much centered in neutral, i did in fact hear just a faint whir noise.

I have again pulled the outdrive. All looks well. I pulled the drive shaft, bearing and gear out of the upper housing again and it looked good. I get 5 inch pounds rolling torque one way, turning the other way it seems to tighten a bit. It may go up to 8 inch pounds. I dont believe it hits 10. Turning back the other direction i get an even 5. I went ahead and removed the nut and will try redoing the rolling torque.

Any ideas whT the issue is? How do i make sure the gears are ok?

 

[williemon]

Currently, after better "setting" of the gimbal bearing and aligning the engine, the noise is not there while idle or reved up on the muffs even when in gear. I only heard the noise for the most part now when in the water and i placed it in gear. I had noticed when testing this last time that in neutral while in the water, tjring the steering to full lock seems to cause the noise to appear.

 

[williemon]

Anyone think this could be an issue with the gearset or with the u joints?

 

[williemon]

I had a chance to look closely at the drive gear set. The gear and bearing pack, once removed from the yoke had a lot of play to it. Roughly 1/8 to 3/16 of an inch. I did not remember it being that loose when I first took it apart. At any rate, I see a wear pattern on the tip of the trailing or flared out point of each tooth that I did not see prior on the drive gear. Im betting that the rolling torque procedure I performed did not turn out right and that has brought me to this.

Is there any hope of reusing this gear set or is it trashed? What would cause this new wear pattern?

 

[williemon]

Any hope at all???

 

[williemon]

Ah gets no love

 

[williemon]

I went to a local marine mechanic and they looked at the drive gear and bearings i took and said they looked fine and that they would reuse them. They thought the new wear was not on the drive side of the gear and said they would re use it. The bearings felt smooth as well. Their observation was that the setup may have been a little loose.

Any one here have any thoughts? Would new u joints make that whir whine? I did not see any end play at all when checking them.

 

[williemon]

Interesting. I checked the direction of the engine and looking froom the front to the stern of the boat, i see a clockwise rotation. Holding the gear in its proper orientation, i see the wear pattern on the drive or load side of the teeth.

Still, any thoughts?

 

[williemon]

Well, i took the old gear and bearing and since it had clearence between the bearing races and the first bearing was hard against the gear, i pressed the second race ad bearing on further till there was just a hair of clearence. Then inused the pinion nut to press it on further che king the rolling torque.

I finally got to a good 4.5 to 5.5 inch pounds of rolling torque. This is for a gen 2 alpha serial number QWxxxxx I then flushed out the upper and lower with mineral spirits, put it all back together and ran it on muffs for a bit. It sounded great at several trim levels and rpms. I then drained that oil and will put in new oil and lake test.

 

[Grub54891]

I think you are on the right track. The gears have to be set absolutely correctly or they will get damaged, and make noise. Hope you have it figured out.

 

[williemon]

I think i may flush with diesl fuel, then use oil again, then drain and put in a final fill. Just want to make sure there are no metal flakes in it

 

[williemon]

I did not get a chance to test today. I have flushed twice with diesel and twice after with stinky oil while it ran on the muffs. Draining and movin a magnet in the oil does not produce any metal that i can see so its looking good so far. I will fill with hi performance for a lake test. Once tested, i will drain and che k the oil cor metal. If all is good, i will refill with hi performance oil.