Metal on plugs?
 

I was having the drive oil changed for winter and the mechanic found substantial metal shavings on the plugs. He, also said the drive oil (Royal Purple) had a tinge of metalic looking color. He wants to tear down in the spring to take a look. This is the starboard drive. Any ideas? Would you have the port side looked at also?
This is the 3rd season with Bravos, Imco lowers. About 45 hours on drives since they were reassembled in the Imco lowers. Still have the Bravo uppers. 700 NA hp.

were the metal particles chunky (large bits) or fine (smooth when rubbed with the finger)?

if the particles are fine...that is pretty common in the bravo 1 drives and im not sure i would worry too much...if the bits are chunky, more than likely one of your gears is getting chewed...

in reference to the metallic looking color in the drive oil...that would concern me...you are also running a lot of power to those bravo 1's...i hope you are gentle on the throttles...

what size boat? weight?

part of me wants to tell you to be proactive and check it out .

but you know they are gonna tell you its popped no matter what,lol

so id run it till it pops because its gonna be the same outcome.


Have you ever seen moroso climbing gearlube?

Crazy stuff I ran it in my race car and until then I blew up rears alike crazy after I started running it I never poped one again.

I havent run it in my OB sportys yet but Id check it out if I were you.

Some metal is ok in a low unit there are wear parts in them and if you do alot of shifting back anf forth on docking there will be more than if not.

Send the oil out for analisys is what Id do.

I ran across this winterizing a buddy's boat a couple years ago. Both magnets looked like Dr. J's afro circa 1976 and the oil glittered with shavings. He had a bearing going bad.

Definately rebuild the starboard one with metal in it. You could save yourself a lot of $$$. I would just keep an eye on the other one.

Anything more than the fine black sludge that is normally
found on the magnets is a problem.

Tear it down.

Monty,
You definitely need to have the one with the metal on the magnets gone through. More than likely the lower gears are going away, but no way to tell without looking. Were there any chunks or flakes on the magnets? That is an indication of gears giving up metal. Not good news, I know, but best to look into it now.
The other drive that looks clean, I would run it and keep an eye on the magnets.

Dick

am i under the wrong impression...if the particles are fine that is perfectly normal?!?! right...i mean gears are rubbing against eachother. small particles is a normal byproduct of friction...the real concern comes when the particles get large or chunky. the magnets arent going to be perfectly clean, that would be impossible...

i wouldnt go crazy if the particles are fine...should almost disintegrate when rubbed between the fingers...

Gears should not be wearing they are hardened but there are dog rings in many lowers like in a jerico type race box and the dog rings can get chunked up a bit.. Thats why I suggest oil anaysis it will tell you what the material in the oil is from.

Is it hardened, is it alluminum, bearing or gears etc.

We use it on construction equipment where the labor costs are very high.

Gears tend to go bad after they get very hot and then cool losing thier hard finish(rockwell) or if they are in misallignment. Usually a bearing going bad is to blame.

I guess it depends on weather you trust your mechanic to be honest with you or just to try and make a Buck off you.

Really appreciate the replies. Mr. Gadget, you set these up 3 years ago and have been worry free, until now. He said there were more than the traditional metal flakes, more like chunks and that it would continue until until it caused more damage. I do trust the guy, but wanted to get opinions on what might be the worst case. It will really bother me to think about this until spring.

Bravo gears are known to be junk. They're always going away. I know with 700hp as I am also even if your easy on the sticks those drives are at/over their limit. If you got 3 seasons out of them I'd say your lucky. Usually starts out as fir on the magnets, hardened surface wearing, time to watch them closely. Then it progresses to flakes, hardening is gone and gear surface is going away. Next is chunks and you waited too long. Expensive enough to replace gears. If you destroy a tower or housing when it blows it's alot more cash to fix or replace. I wouldn't wait until it pops. My 2ct's.

I would do it now as opposed to the spring... offseason is thetime to fix stuff, not waiting for it to get fixed when the suns out and your standing on the dock wishing it was done already.

The lower Merc pinion gear tests at rockwell 48-52. The driven gear tests at 56-59. After 5hrs of running I have seen the pinion gear start to disenegrate and the driven looks new. Why the pinion gear is so soft, is a mystery to me. They build them and sell them by the truck load.... like fire said.. JUNK!

The Imco SCX gears are much harder and last ten times longer.

Dick

Sounds like a market to make some money to me, reverse engineer some gears with a harder rockwell and your in business.

we use PRO (softer) gears in drag racing so they bend instead of break. they absorb more shock this way. they dont last long though maybe one season if your lucky. They tend not to shatter though like regular hardened gearsets.

WORST CASE the gears shatter tetch get caught in the gearset and spread the case breaking the entire housing and your buying a whole new unit.
Plus paying sea tow to get you home.:eek:

Best to get it fixed in advance of a major failure. Like split case or tower from gear teeth hitting the inside walls. Then the only parts to salvage will be........nothing.

cheaper now, much more expensive later. Plus better to get it done in the off season.

Will the Imco gears go in the Merc XR case?

No. They are much larger than XR gears.

That is correct, they are too large. Too bad they dont fit. Lots of people have tried to reverse engineer them but the cost is high and not an easy task.

More than likey the gears are made of two differnt types of steel. Its not good to have the same type material with the same RC working together.

Does anyone know what grade tool steel these are made from? I figured it would be 4140/brake die.

8620 or something close to it, from what I have been told. And both seem to be the same material.

Never heard of that grade steel. I wouldnt have thought that it could get in the hard. Do you know if it is a through hardened steel? I am more fimilar with tool steel grades - A2 D2 D5 S7 CPM etc.

it is not through hardened.. just surface.. gets real mushy the deeper you go..

Case hardening
 

The metallurgical process you are talking about is "case hardened" steel. The "case" provides for a lasting long wearing surface and the steel is soft and shock resistant underneath. Surface breaking or "brinelling" is result of insufficient design strength of the whole part sort of welding itself together under pressure and load. This causes the breaking of the overheated steel surface.

Case hardened crankshafts were used for early roller bearing engines and connecting rods as well as gears and shafts - 1920's technology. Charred bone was packed around the part and it was heated, cooled, heated then finish ground. Later hardening method was carburizing oil treatment. Deep case could be reground and the part reused. Once the case breaks the flaking of the steel continues and the part is basically not repairable. Welding will not work, chrome will just flake off, stellite resurfacing was used with success in the WWII era. Most of these methods are used today in repair of antiques, but it is often easier to just have new parts made from scratch. Be glad you can just get the stuff from Merc.

You might try the gears from a diesel drive as I hear they are substancially stronger.

There is no difference between the diesel gears and the others. It used to be they did a shop peen process to them, but they were thin floored gears and that was over 10yrs back.
Merc used to supply decent quality gears, but as of late, they seem to fail at a much higher rate than they did 5-6 yrs ago.
The hardening on the lower gears does not go very deep. The hardness falls way off as you remove metal in .010" increments. Friend of mine has played with them extensively.

Dick

Merc and the failing parts
 

Dick - have been reading the 105 or so pages of this site - you seem the man in the know on sterndrive. As for me, just left the antique world and bought a Donzi - getting aquainted with the whole Merc thing - Dr. d

Welcome to this world and OSO!! Boats are fun when they run!
And thank you for the comments, we all learn from sharing knowledge..

Dick