Lower Unit? Power head? Or Something Else?

[forrestercb]

I have an 07 225 vmax hpdi series 2 that just had the power head rebuilt late November by hydro tec. I've only had it out twice since the rebuild and today while running at 5000 rpms I started to notice a knocking noise and then I felt something as if the prop had cavitated (it didnt). I immediately shut down and trolled back to the ramp. I feared it was the power head again but when I got home and checked compression all cylinders checked good. All plugs looked good and had good spark.
Could a lower unit cause that knocking and other symptoms? Can you have good compression but still have a blown power head? Or is this something else?

[Musky Mike]

Why was the power head rebuilt?

[1ranger487vs]

It’s a big block hpdi

[yam911]

It’s a big block hpdi

Yes, a 2007 VZ225TLR uses the 3.3 liter block.

[yam911]

Yes, a motor can have good compression and still be blown. Blown having many many meanings.

Yes, the lower unit can cause knocking.

Time to get the motor to a Yamaha mechanic for an inspection. Hopefully it is just something relatively minor.

Good luck.

[forrestercb]

Why was the power head rebuilt?

One of the cylinders was destroyed due to a retaining pin coming loose.

[Nutoy]

My '09 HPDI did the exact same thing. I thought it had blown the power head, but I figured it's already shot, so I idled back to the ramp. While idling,I noticed if I gave it a touch of throttle, the knocking would change slightly. If I put it in neutral, the knocking would almost go away.
Came home and did a compression test. All good.
Reached down and spun the prop. Knock, knock...

It was the pinion bearing had come apart and knocked a couple teeth off the pinion gear and the forward gear.
Replaced all the bearings and gears. $890 in parts, and had to re-shim everything due to new gears.

If it is the lower, have someone that knows what they are doing tear it TOTALLY down and inspect. Unless something is locked up, they can have it apart in 15-20 minutes.

HPDI's loose LU lube over time. It's just what they do.
Check lube level a few time during the year and top off if needed.

[forrestercb]

Pulled the lu drain plug and found metal shavings on the drain plug. Gear lube is completely gray with metal shavings in it. Lower unit was worked on at the same time I had the power head replaced.

[forrestercb]

The mechanics had just installed a new pinion gear, thrust bearing, thrust washer.

[mrdeath]

Call them. They'll warranty it.

[Thamelau]

I may be overreacting, but if I had a gear worn to the point it needed replaced, I would get all my gears replaced in that gearbox. If they just replaced the pinion, I would guess the driven gears would be pretty worn as well.

[Nutoy]

The mechanics had just installed a new pinion gear, thrust bearing, thrust washer.

Sounds like somebody should have done a farther inspection when they were in there the last time.

Usually, if a bearing or gear fails, it will take out other bearings due to the metal shavings getting into everything. The prop shaft bearing and the reverse gear bearing inside the bearing carrier is often overlooked.
If they didn't shim the new gears properly, it will cause a failure as well. You can not go by the old shim specs when installing new gears. It must be done properly so the new gears have the proper slack and backlash.
It takes someone that really knows what they are doing to get it right.

Like mrdeath said, call them and see if they warranty it.

If not, I have a couple extra LU's.

[forrestercb]

Sounds like somebody should have done a farther inspection when they were in there the last time.

Usually, if a bearing or gear fails, it will take out other bearings due to the metal shavings getting into everything. The prop shaft bearing and the reverse gear bearing inside the bearing carrier is often overlooked.
If they didn't shim the new gears properly, it will cause a failure as well. You can not go by the old shim specs when installing new gears. It must be done properly so the new gears have the proper slack and backlash.
It takes someone that really knows what they are doing to get it right.

Like mrdeath said, call them and see if they warranty it.

If not, I have a couple extra LU's.

I took my motor to hydrotec for my my blown powerhead but while it was there they also did an inspection of the lower unit. In the lower unit they found the thrust washer severely warn, also the carrier bearing showed signs of excessive wear. They also discovered missi g teeth on the pinion gear. All parts were new with EXCEPT the pinion gear, which was replaced with a used one. Hydrotec is one of the most if not the most reputable yamaha shops in the country so I trust their inspection and trust they will make it right.
Hydrotec said they would make it right so long as the failure was related to the work they did, which I think it is. Ive got the lower dropped and removed the water pump and the drive gear is all but locked up, you can turn it a little bit but hear nasty grinding and crunching in the gear case, prop shift turns fine though.
I'm just hoping I can get this fixed and back together before I leave for tournament championship on guntersville at the beginning of march.

[Nutoy]

I took my motor to hydrotec for my my blown powerhead but while it was there they also did an inspection of the lower unit. In the lower unit they found the thrust washer severely warn, also the carrier bearing showed signs of excessive wear. They also discovered missi g teeth on the pinion gear. All parts were new with EXCEPT the pinion gear, which was replaced with a used one. Hydrotec is one of the most if not the most reputable yamaha shops in the country so I trust their inspection and trust they will make it right.
Hydrotec said they would make it right so long as the failure was related to the work they did, which I think it is. Ive got the lower dropped and removed the water pump and the drive gear is all but locked up, you can turn it a little bit but hear nasty grinding and crunching in the gear case, prop shift turns fine though.
I'm just hoping I can get this fixed and back together before I leave for tournament championship on guntersville at the beginning of march.

I have heard nothing but good on the Hydrotec guys.
Hopefully you'll get it taken care of in a timely manner.

[forrestercb]

I may be overreacting, but if I had a gear worn to the point it needed replaced, I would get all my gears replaced in that gearbox. If they just replaced the pinion, I would guess the driven gears would be pretty worn as well.

Ding ding! Mechanics got back with me and said the suspect the forward drive gear was in bad shape and caused the failure. They admitted they missed it during their inspection. They also said that everything in the gearcase is pretty much trashed. They want me to pay for the cost of parts which he estimated roughly around $1500. No so sure I agree with that. Why do you guys think?

[Nutoy]

Ding ding! Mechanics got back with me and said the suspect the forward drive gear was in bad shape and caused the failure. They admitted they missed it during their inspection. They also said that everything in the gearcase is pretty much trashed. They want me to pay for the cost of parts which he estimated roughly around $1500. No so sure I agree with that. Why do you guys think?

If everything is trashed, it's going to be north of $1500 to get it repaired. Just the gear set is going to be around $900-$1000, and the major bearings is another $400, not to mention labor.

I don't understand why they want to pay you for the parts, when they could repair it and send it back to you,,, with full warranty.

[forrestercb]

They said they wouldn't charge me labor and would split the costs of the parts.

[Claytonsdad]

I'm no mechanic, but it would seem fair to me for them to cover the cost of everything they did originally at a minimum. That would leave you with the cost of additional parts and labor for replacing whatever they missed the first time. In the name of good customer relations, they could also do something to compensate you for having to make a second trip. Just one guy's opinion though.

[Ranger519VS]

I have always been told mating new gears to old gears is a no no.

[Nutoy]

I have always been told mating new gears to old gears is a no no.

This is partially true.
When replacing gears, be it all of them or just one, the shimming process must be completely redone. The same shims can not be reinstalled as they were before the repair.
The gears must have the proper amount of "slack" or they will fail again.

Most times, when a gear or a bearing fails, the pieces get "ground" up and damage other components, especially the other bearings.
When you find what looks like an abnormal large amount of metallic powder on the drain plug magnet, it's a good idea to have a inspection done before the LU craters.