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Pinion Gear Carnage

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ryan00tj

Contributing Member
"Background......

Built a n

"Background......

Built a new Alpha 1 over the winter. Used GLM lower gears and HD 1.50 upper gears. Shimmed per the FSM and it's set up right. Ran great all summer and gears were broken in per GLM instructions. At 82 hours on drive I noticed gear oil resevoir bottle offcolor. I pulled drive and found water contamination. I replaced all seals and fixed problem. I then totally pulled drive apart and cleaned all parts along with case. Gears were fine at this point. Reassembled and refilled with oil and went back to boating.

A few days ago, 125 hours on drive. I pulled the boat and drained the lower unit oil and the magnet was covered with metal. I pulled the drive apart and found everything ok except the pinion gear teeth have started to come apart and scall as you can see in the pics. All pinion teeth except three are like this. The F gear and R gear are ok. Upper gears are ok.

Did the water mixing with the oil hurt the gear and then it started to wear? Anyone have any ideas or similar experiences? I use Mobil 1 Syn 75W-90 and change it religiously at 25hr intervals. Drive shower on drive.
355ci 400hp SBC


I have a spare Alpha 1 with HD upper gears also so I threw it on so I can still enjoy these late Sept 80* boating weekends.

I plan to replace the lower gears over the winter with a new set of Merc gears and will redo the bearings as they got some metal pushed thru them.

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"I have a old outboard with a

"I have a old outboard with a cracked lower unit. I use merc gear oil and it will turn milky each use but letting it sit for a day or two, water seperates from oil and goes to bottom of unit. I drain water out of lower unit, add a few ounces to top it off and continue running it. Been doing it for 22 years. (lower unit is 50 yers old and no replacements available). I tried using auto gear oil but it would turn milky and creamy like peanut butter and it will not lube properly, actually it will quit lubing completely.
Mobile 75w-90 makes my head hurt. All specifications I have for outdrives specify Quicksilver Super Duty Gear Lubericant. This stuff has superior lube qualities and if water contaminated, will continue being fluid.
Your attachment is a little blurry but what I can see is a gear the looked like it ran dry.
When you noticed the milky oil, the oil in the outdrive probably turned to goo and the gears spun/flung the goo to the side of the gearcase and continued to run mostly dry. The case hardening of the gears is only .01" or less thick, when you opened it up, it may have looked ok but actually the gears had worn just beyond the case hardening and looked ok at the time. After putting it back together, the now soft gears kept on self destructing especialy if there was a still hard gear running in the cluster/set.

You will have to replace all gears as a matched set.
I believe if you were using Quicksilver or OMC gear oil, you would have not lost your gears even when water contaminated because this brand of oil does not turn to goo when wet.
Your outdrive with 400 hp may not be very reliable if run hard."
 
"Thanks for the reply. I will

"Thanks for the reply. I will rebuild over the winter with a new set of Merc gears and new bearings. It's not to bad when you can do the work yourself. I plan on switching back to Merc's synthetic as I bet it will protect better just as you mentioned. As to the Alpha, i've been running 350-400hp SBCs through them since 92 with no failures."
 
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