Housing Bearing (and Bearings) Failure - Jet Pump Unit repair

[dzeppos]

I have a 2016 Yamaha 242 S that I purchased brand new, and over eight great boating seasons, now has almost 400 hours .
The boat has mostly been trouble free since inception (other a few minor adjustments).

Finally, on our last day of a week long lake boating trip, we heard an awful cavitation sound once we hit the throttles coming from the Starboard engine.
Our initial reaction was that had been sucked into the impeller. After pulling the boat out, we realized that there wasn't anything in the impeller, but an awful vibration from the starboard engine from inside the engine compartment.


The boat mechanic I use, (who's been incredible and has been servicing my boat since I purchased it) realized that it was a bearing issue at the jet pump (on end of the cone) - and that two bearings were bad.
The damage from the vibration also caused some damage to the housing bearings inside the boat (inside the engine bay)
But it was the actual housing - the unit bolted on the hull that was loose. It seems like it wasn't done correctly from the factory almost 8 years ago, and it loosened over time, which caused the vibration which in turn damaged the bearings.

The worst part is that the labor required taking off the catalytic converter (Thank you California and the unnecessary and over the top environmental requirements) to get to the bottom of the bilge to move the engine so that they drive shafts and bearing/housings could be replaced.

I’m almost fortunate that took 7+ years to have this issue come about, which was clearly done wrong from the factory. Unfortunately, the cost in labor and parts was significant. He also checked the housing bearing bolts on the Port engine (which was running fine), and found that the housing bearing bolts were also somewhat loose. However, there was no damage and he tightened those bolts as well.


The issue is that it wasn’t that the bearings went bad, but that the loosening over time starts of the housing bearing to the hull caused the boat to cavitate and damage the bearings (on both sides of the jet pump unit).



I offer this post because my mechanic who's been working on Yamaha boats for 20+ years and had never seen this issue (from the housing being loose). He says there’s no way anyone could have tampered with that and it was improperly put together from the factor. I don’t know if anyone else ever encountered this issue with the jet pump drive unit (as connected to the engine). There’s nothing in the manual that says this housing bearing unit needs to be tightened or adjusted/inspected.


On the upside, the Starboard engine is now very quite at idle. Its never been this quiet. At 5500 rpms, its much quieter as well. My Port engine is somewhat louder (typical sound since I bought the boat) but well within the norm.
In addition to replacing the air filters and getting the housing exactly aligned, we test ran the boat out in the ocean today and had incredible performance on all rpm levels. It seems like my boat runs better and quieter than it did when it was new.



Happy to discuss or offer additional comments, but despite the cost and being out of service for 7 weeks, the boat runs better than new.

And if you need a referral, Dan is the best mechanic out there in Southern California. Just let me know,

 

[Bottom Bracket]

Dealer service includes intermediate bearing inspection. Should have been inspected at least seven times. What is the condition of the port intermediate bearing?

 

[Cobra Jet Steering LLC]

There are many posts about pumping grease in the intermediate bearing housing and not adding grease but gear lube and same for the pump, I get twice the hours on my bearings adding gear lube to those rather than grease since it liquifies the existing grease and spreads better and a grease gun can damage the intermediate bearing housing where it is attached to the metal housing just by the way it is designed. Search this subject.

 

[dzeppos]

Dealer service includes intermediate bearing inspection. Should have been inspected at least seven times. What is the condition of the port intermediate bearing?

The bearings looked fine up until the incident. It was the bearing mount holes on the hull -(specifically one was not drilled correctly (saw it first handle) and eventually caused to to fail

 

[Cambo]

Did the bearings on the jet nozzle have any water in them? That's usually what makes them fail I check my bearings at 200 hr intervals. I'm going to check the intermediate bearing bolts first time I have seen that come up. Any pictures of your wear rings did they need to be replaced as well?

 

[dzeppos]

Yes, but only two bearings were bad. I can get some pictures to show the damage. But all that said, the major expense was having to get down below in the engine bay and replace the housing bearing (and the hole on the engine hull was not aligned correctly from day 1 from the factory).
The oddity was that the bearing housing on the port (non-damaged) drive was also loose, and the only way you can get in there is if you have the engine moved (catalytic converter removed - its impossible to get down there) to tighten that as well. Not something you normally check

 

[Neutron]

Yes, but only two bearings were bad. I can get some pictures to show the damage. But all that said, the major expense was having to get down below in the engine bay and replace the housing bearing (and the hole on the engine hull was not aligned correctly from day 1 from the factory).
The oddity was that the bearing housing on the port (non-damaged) drive was also loose, and the only way you can get in there is if you have the engine moved (catalytic converter removed - its impossible to get down there) to tighten that as well. Not something you normally check

Can you take a picture of what bearing housing you are referring to that was loose?
Intermediate bearing?
If it is then the bolts are accessible without engine removal. To replace it the engine needs to just be slid forward.

 

[dzeppos]

It was the Housing, Bearing -that is fastening to the hull of the inside engine Compartment (there are three holes for that to mount. One whole was misaligned and not correct (from the factory)
Actual Part # - 66G-45331-01-94 66G-45331-01-00

Yes - they didn't have to remove the engine, just slide it forward so you replace and fix the parts down there. But its the 4star Catalytic converters that get in the way of doing any substantive work at the bottom of the bilge area.