View Full Version : Upper Gear Housing Oil Seal
03-26-2006, 11:56 AM
"I split the lower unit from the gear housing to replace the impeller. The gear oil was a little cloudy, but no free standing water when I pulled the plug. It's been sitting all winter, so if there was significant water in there, I would think it would have settled by now.
Anyway, when I pulled the lower unit off; I got a little more oil than I'm used to, and it seemed to be in the cavities where oil usually isn't.
I may have been too quick to yank it off, the reservior may have still had oil in it.
I can't tell from the exploded view diagrams if the lower unit veritcal shaft mates to the seal in the bottom of the gear housing, or if the driven gear shaft in the upper unit mates to the seal. Anyone know?
If it's the lower unit verical shaft that mates to the seal, I may be OK and I just got the deluge of oil when the vertical shaft pulled out of the seal.
If it's the driven gear shaft that mates up... I guess I'll be pulling off the rest of the drive to replace that oil seal... and everything else made out of rubber while I'm at it."
03-26-2006, 03:18 PM
"There are two seals, one that seals on the driven gear up in the housing and one that is at the entrance of the housing and seals on the vertical shaft. If your vertical shaft has a oring groove, look up inside and make sure you have the oring out. If you pulled it up before it drained all the way you would get a bunch of oil."
03-27-2006, 07:18 AM
"Thanks Harves, I see the two seals on the diagram now. There is no O-ring groove on the vertical shaft, but there is some sign of wear... just a little scoring I can probably clean up with emory cloth.
I'll have to take a better look at the vertical shaft oil seal now that the rest of the oil has drained out.
From the diagram, it looks like the only way to replace that oil seal is to pull the gear box apart."
03-27-2006, 10:54 PM
"Troy, you can use a seal puller or a slide hammer with a seal puller to pop the seal out. Install is reverse, clean the bore with a non oil cleaner and use Loctite 671 to "glue" the seal in. Press in flush with the housing."
03-28-2006, 06:57 AM
"Too late... it's already back together. The shaft cleaned up very nicely. It actually wasn't worn or scored. The way it looked at first, it did appear to be scored. It had some residue on the shaft everywhere except for where the oil seal rides. The oil seal was in pretty good shape.
It's good to know I can change that seal from the bottom, if it does end up leaking on me."
03-29-2006, 04:50 PM
"You got it, have a good season."
05-20-2006, 07:18 AM
"Why do I have small amounts of water coming out of the top cap on my outdrive. There is also a high pitch wing coming from the outdrive when it's running. I should say that this is a new upper half outdrive. I installed it yesterday, put the the correct amount of gear oil in and thought I checked all seals. What did I forget ?"
07-23-2006, 09:21 PM
"I HAVE A 1982 MERCRUISER MCM470 224CID - I RECENTLY HAD A NEW WATERPUMP PROFESSIONALY INSTALLED. I JUST TOOK IT OUT AND WITHIN 20 MINUTES RUNNING. I START HEARING A KNOCKING COMING FROM THE OUTDRIVE OR THE LOWER UNIT. (THE KNOCKING MATCHED MY RPM) I PUT IN NUETRAL AND REVED THE MOTOR. SOUNDS GREAT. ONLY HAPPENDS IN FORWARD AND REVERSE. AFTER GETTING HOME, I PUT IT IN FORWARD GEAR AND BY HAND I TURNED THE PROP IN THE FORWARD DIRECTION AND HEARD A KLANKING / GRINDING NOISE AS IF THERE WERE GEARS SLIPPING. WHILE STILL BEING IN FORWARD POSITION IT WOULD NOT SPIN IN REVERSE. SAME APPLIES FOR THE REVERSE GEAR. SAME NOISES. I KNOW ON OUTDRIVES THE PROP WILL NOT SPIN UNLESS THE MOTOR SPINS. I AM NEW TO INBOARDS AND OUTDRIVES. ANY SUGGESTIONS?"
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