OUTDRIVE OIL TURNED BLACK-gctid814914

[bucluv]

HI all. i have a mercruiser bravo 2 drive & use high performance gear oil, that greenish blue stuff that i have always used in my mercruiser drives. i changed the oil begining of the season & only have about 11 hours run time so far this year. i checked my oils this weekend & noticed the drive oil in the reservoir is black. The boat is a 2005 305 & i bought it the end of last season. When i changed the oil at the beginning of the season it was also black. I have owned mercruiser drives all of my life & never came across the oil turning black. The boat runs great, ..... any ideas ???... thanks in advance

[Pcpete]

It could be a change in the oil chemistry. Have you changed to a heavy duty or synthetic? Are you using the Mercruiser/Quicksilver oil or another brand? For what it's worth, my drive oil in the Alphas and pre-Alphas I owned in addition to my sons B2 all changed the oil darker but retained a bit of the green tinge as it was allowed to thin, like on the side of a jug that had been emptied. I also stuck with the brand name stuff, but for no particular reason other than when someone suggested another brand all the evidence they had was what came out of their mouth. No printed documentation about certification and applicable uses.

Just my experience, don't try it at home, I'm no professional and could be a bad example. :whistle:

[Chief_Alen]

Drain the drive, see the drain plug ? it have metal pieces stuck to it ?

After draining, remove the plastic bottle off the engine, clean well install, now pour a little fresh gear oil into the bottle let it drain out the drain plug, will take a while, don't rush it . When you see pristine oil coming out the drain your know you washed the hose and drive clean.

Now fill from the bottom slow, let the drive burp.

[bucluv]

thanks, I've always used mercruiser high performance gear lube & in the begining of the season when i changed the oil i did clean the reservoir & pour new oil thru to clean out the lines & drive, then added new oil.....no metal shavings where on the drain plugs. the boat runs great & I'm planning on taking a few trips very soon, but now I'm little worried

[msd58]

Did it smell the same as did when you put it in?

[bucluv]

Yes.. I made sure I smelt it to make sure it smell the same this never happened on any of my drives before just curious why it's happening now

[GearGuts]

I have learned a few things about oil over the years and one of them that could be of some use here is that oil that darkens over time is a reacting to high temperatures. I'm not absolutely certain what actually happens but when machinery runs hot the additives in the oil overheat and darken. I'm not sure what "additives" are since it seems to be a trade secret among oil giants and my experience is in this area is purely industrial so whether or not this would apply to marine gear oil I don't know for sure but a temp gun over the transom at speed might give you peace of mind that the drive is not running hot.

[msd58]

"bucluv" post=815223 wrote:
Yes.. I made sure I smelt it to make sure it smell the same this never happened on any of my drives before just curious why it's happening now

Post this over at iboats.com I am sure you will plenty of answers.

[sketch96]

The only reason oil will turn black is high temps. The b2 unit that I have on my new boat was black also when I changed it. From my understanding the bravo units run hot. I have bought a drive shower for mine. Haven't tried it yet. I added a thru hull raw water intake and plugged off the water intake from the leg at the transom. This requires a drive shower. I'm hoping it solves the dark oil issue.

Fyi. The P.O. ran only the high performance Merc leg oil. Maybe this oil does not handle higher temps well?? Maybe Mobil 1 synthetic gear oil might be better?

[Ruffryder]

Doug, didn't you cut the raw water hose at the bell housing? So it still cools the drive?

That is what you are supposed to do when converted to a thru hull intake.

[sketch96]

I'm still working on the transom rebuild but when it all goes back together I will be cutting the intake hose where Merc recommends. With that and a drive shower it should help.

[fishaman]

I remember reading a speed boats forum where they discuss how to turbocharge a 7.4 with Bravo 1, and part of the best practice was to install a 1/8" drive oil temperature sensor instead of the upper oil plug. Then the wire is routed to the dash, and oil temperature is monitored in real time. Will be great to have in a weather like last weekend in San Juans.