Some water in lower unit. ? Seal or forced in with Muffs!

Expidia

Commander
Joined
Aug 26, 2006
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2,368
2007 40 4 stroke.
Had prop bearing carriage replaced after cracking the outer ring by a Merc dealer last season. This bearing supports the whole prop shaft assembly.
When I went to renew the lower unit fluid at this seasons start I noticed about a 1/4 cup of water came out first before the fluid came out and (I would have thought water would come after the fluid since its lighter than oil).

Anyone think I may have forced some water into the lower unit by using the muffs which I warmed it up before I took used it out yesterday on the river for my first time out. I thought I read something where one should not use too much water pressure when using the muffs.

If a seal is leaking then it could have been leaking from after they did the bearing carriage replacement which means there was water in the lower unit while I was using it through the season. Could this have done irreversible damage to the bearings?

it does sound a little noisy and shaky more so in reverse when I ran it back on the muffs after I changed the gear oil. Looked a little shaky in forward gear too. But maybe cause it's out of the water on the muffs. I can't remember if it was quieter before the bearing carriage was replaced. Seems to run fine though on the water although I was only doing around 10mph as it was only 50 degrees on the river yesterday and my wife has no windshield in front of her seat.

I put a call into the shop that did the repair but might be too early for their shop to open yet.

I was going to run it on the river again later this week and then change the fluid again to see if there is any more water in there.

Thx for any insight into this issue.
 

aussieflash

Lieutenant Junior Grade
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Feb 5, 2011
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1,004
Re: Some water in lower unit. ? Seal or forced in with Muffs!

2007 40 4 stroke.
(I would have thought water would come after the fluid since its lighter than oil).

Your right,Oil is heavier than water...BUT water has a higher density than oil,so oil floats on water.
You got a shot seal...im guessing where they did the recent repair.
 

Expidia

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Re: Some water in lower unit. ? Seal or forced in with Muffs!

thx for that reply. Ya, I was leaning towards the rear seal. What worries me that it might have been leaking since they did the repair which might mean it was leaking all of last season. I wonder if the innards are now corroding, if water was sloshing around all that time around the gears?
 

Expidia

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Re: Some water in lower unit. ? Seal or forced in with Muffs!

Update: refilled lower unit last week. Used the rig past Thurs on Lake George for 5 hours. How sweet was that . . . 83 degrees and no wind in NY for March 22nd, I might see an 8 month boating season this year :D
Spoke with Merc mechanic and he said to bring it in and he can pressure test it for leaks. He said it might be leaking up around the water pump area. I said I was going to run it on the lake on Thurs and then drain it again to see if any more water. If so, I'll bring it in to him.

Drained it today and not a drop of water! My two guesses are #1 water ran down off the inside of the leg when I brought the O/B to an upright position and mixed in as I pulled the drain plug (but it seemed to me water was coming right out of the hole as soon as I pulled the plug).
#2 maybe I hit something near the end of the season (I did have to touch up the prop) causing enough of a jolt to the lower unit to let a little water in somehow, maybe around the sharft. Running on the Hudson River one can easily hit a submerged log especially just after a tropical storm like the one that whacked upstate NY and dumped much debris into the river right at the start of stripper season last year.

Either way, I'll run it for a month and re-drain and re-check for any water.
 
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