mgreenspan

My drive failed last week, and my insurance company and mechanic disagree on the cause.

The drive ws serviced last fall, including replacement of the impeller and sea water pump kit. The prop was also refurbished.

The first trip out this year, my 15 year-old engine failed. I had it replaced with the same model (5.7L 260hp carburetor). When they remounted the sterndrive, they topped off the gear lube. There was no indication of a problem.

The drive failed the first trip out after that. The engine revved up, and the drive stopped turning. I thought I might have spun the prop hub, but when they broke down the unit it was a mess. The propeller showed sign of an impact, but it was not extensively damaged. The drive showed no impact damage.

The insurance company claims this was a mechanical breakdown due to lack of lubrication, and that was due to lack of maintenance. They cite the fact that the drive wasn't pressure tested last fall, so there is no way to know if it was leaking at that point in time.

The mechanic says it was a sudden failure due to impact. He claims that pressure testing a drive is not routine maintenance, and wasn't needed since the gear lube showed no signs of a leak. He says that the upper bearing was not that damaged, and it would be one of the first parts to show extreme damage if the gear lube was low for any period of time.

So, who is right? Is the pressure test routinge maintenance? Would the bearing show more heat damage if it was out of oil for longer than the 10 minutes I ran it before it failed?

Thanks for the help.

happy hours

I agree with your mechanic. Alpha ones have the upper gear set and upper drive bearing bathed in oil. I know from when I was a kid and lots younger and dumber that if you fill one incorrectly and the upper end runs at an oil level lower than it likes you burn up the top cap bearing first soon followed by the upper gears and drive bearings. With no extreme heat damage to those parts low oil was not the case. But a pressure test is not that bad of a thing to perform every now and then , as it a great way to check the seals out as a leaking seal kills lots of drives. I am no drive expert but am a mechanical engineer and know a little about power transmission. (and I stayed at a holiday inn express last night). No lubrication (oil) makes stupid high heat in seconds in tapered roller bearings and will kills them in seconds under a load. And the way the drives are assembled they always have a load ( bearing preload).

fund razor

yeah... what he said.

Pressure testing is not routine. Most leaks reveal themselves one way or another.
If your prop was stainless, it may reveal the severity of the impact.
It broke right before it revved. Not after.
Keep the mechanic. Lose the insurance company.

bowtie

Low on gear lube, upper bearings will go first then the upper gears will mushroom. Get yourself a private adjuster.

jpclear

I too would back the mechanic. The insurance co. is trying to bail as they will anytime they think that they can get away with it. Lawyers love to eat those guys. find yourself a barracuda and turn him loose! --- JP

jaroot

mechanical engineer #2 agrees with mechanical engineer #1...

i also have rebuilt or been inside of well over 100 alphas.. including mine AT THIS moment... well an alpha SS... close enough

i struck a log at lake cumberland in the spring at about 50 mph... no visible damage to prop... extensive surface damage to gearcase... the upper gears went soon after.. like 1.5 hours... i was happy she held together that long... i knew it was hurt.. i felt the vibration... then heard the knock start and progress and finally it got really nasty when teeth got between intact teeth... luckily it self destructed at an idle and i could just kill the ignition... the lower gearset went less than 2 hours after that... and i never once hit WOT... they "looked" perfect wehn i disassembled to clean and inspect.

i was also a mechanic at a large marina in southeastern michigan for 3 years in the early 90's... pressure AND vacuum testing was SOP for us... double lip seals require this procedure...

the top cap bearing will show extensive heat in a low oil situation followed by the forward drive gear bearing and the actual drive gear shaft that the bearings press onto...

if the uppers went due to impact have the lowers magnafluxed or x-rayed before reassembly... and vice versa... i learned that hard way...

a drive shower is beneficial for the alpha upper gearset imo...

mgreenspan

Five votes for the mechanic, zero for the insurance adjuster. Thank you all for the feedback.

I will take bowtie's advice and get a private adjuster.