Ok, so I might be an idiot. I was changing the lower unit (gearcase) oil on my 200 Yamaha hpdi. It takes a bit more than a quart. I drained the oil. When refilling I pumped the first quart in and then replace the top screw (oil level) so that I could pull the pump out of the bottom, change quarts without a whole bunch of fluid draining from the fill hole, and then pump a bit more to fill the gearcase.

Well, I left the top screw in just a little bit and began pumping more fluid in thinking a bit would ooze out telling me it was full. After a few pumps from the second quart fluid starting come out of the little hole (not a screw hole, I think it's the hole that tells you your mph) and a bit of oil also came out of the propeller where it would exit the exhaust. I removed the top screw and maybe a couple ounces drained before getting to the right level. I hope that made sense.

So, the question. Do you think by adding a couple extra ounces to the lower unit I could have blown any seals or would the bit of overflow out of the two places I described be a non issue?

I've done this service to all my motors and never forgot to pull the top screw back out when starting to pump from the second quart.

Whoa... sounds bad, Dave. I've never heard of that happening and wouldn't consider it a non-issue. It really makes me wonder what seal could have blown though for you to see it in two spots.

I think the easiest way to find out is to go run it for a while in some fresh water. Bring it home and drain at least some of the lower unit oil back out. If it looks milky, you've got a hole somewhere. If it looks OK, take it out for a real trip and then re-check. If you go a few trips with everything looking OK, then I'm not sure what is happening? It is hard to believe you would have blown something out just from the pressure of the pump. I'm probably not telling you anything you don't already know but that is what I would do.

Good luck and I'll be curious to hear what you find.

-Kaiser D.

At most I pumped 1-2 ounces too much fluid in there. I thought with the top screw almost completely loose some fluid would ooze out letting me know it was full. I usually have the top screw completely removed but just thought.... well, I hope I didn't F-up.

Make sure you close the top screw all the way when changing quarts. Leave the top screw all the way open when filling. When oil comes out the top its full. I would drain it again and start over. If you see the same thing happen then something is wrong. Also make sure that oil is coming out of the places you mentiond and it just not spillage that looks like a leak.

First, I know I screwed up. Second, I can't believe a seal would blow by the pressure from a couple (at most) extra ounces of fluid.

I'm going to talk to one of the techs tomorrow but would still like to know if anyone has experience with this. Any chance there is an overflow valve inside the lower unit causing fluid to leak into other areas or did I more than likely blow a seal? That doesn't sound too likely to me because if oil can get out water can get in? Sorry to beat this to death but it's on the brain right now.

After a little further reading, I really do believe you've blown at least one seal in there. Although neither of these is exacly your problem, they do both reference the possibility of blowing internal seals by putting too much oil in the lower unit. I have no idea what is involved in the fix but, unfortunately, it seems like something will have to be done.


http://www.usboatingclub.com/cgi-bin/yabb/YaBB.cgi?board=008;action=display;num=1113173600

http://www.tmtanglers.com/forum/viewtopic.php?t=752&sid=b94ca0ba7bbbf8d9ccf05e08d30a8649

Good luck. If you need a ling fix, send me a PM and take a drive up to Bellingham.

-Kaiser D.