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Author Topic: Lower Unit  (Read 3946 times)

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Offline Grinder

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  • '79 CVX 18
Lower Unit
« on: March 18, 2011, 11:37:40 AM »
Does anybody know what can cause pressure in the lower unit? This is the same problem I had last year when I pull the vent screw out the lube shoots out about 4-5 feet. This I believe is also the cause of what looks like gear lube in my bellows and bilge.
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Shaun
86 CVX 18

Offline Jason

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Re: Lower Unit
« Reply #1 on: March 18, 2011, 12:17:12 PM »
Maybe your getting water in the lube?

It does not seem like a change in air temp from the last time you removed the vent screw would be enough to build that much pressure. but who knows......
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Jason S.
1974 Glastron Carlson CV16SS 140 I/O
1986 Glastron Carlson CV23 260 I/O

Offline Grinder

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Re: Lower Unit
« Reply #2 on: March 18, 2011, 12:37:57 PM »
I didn't see any water, looked clean.
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Shaun
86 CVX 18

Offline wiliermdb

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Re: Lower Unit
« Reply #3 on: March 18, 2011, 01:36:51 PM »
Found this info posted on another forum.

I remember mine doing that on an older boat I had when I did the maintenance during the winter and then serviced again during the summer.

From another forum.)  It is somewhat normal to come out fast as you described. If there is any air pressure difference, it doesn't take much. We see that in the spring when its warmer out from gearcases that were filled in the fall when its colder out. Say the level was set/filled when its 45 degree's. Then in the spring you check it a 70 degree's. The oil will expand some with the heat difference and that expansion will cause air pressure difference. Hence the oil squirting out when you take the plug out.

Kind of like a can of pop that you shake up? That builds up pressure, and when you pop the lid......POW!

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Offline CVX Fever

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Re: Lower Unit
« Reply #4 on: March 18, 2011, 01:54:01 PM »
Shouldn't have any oil in your bellows. You might have a bad seal. Myself, I've never experienced gear lube shootng out of the vent hole when changing. So I don't know if that is normal or not. I'm sure Rich will have a good answer for that question.
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1979 CVX18 "Back in Black"....someday!
1985 CVX18 " Only thing better than 2 CVX18's is 2 girlfriends!

Offline Rich_V174SS

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Re: Lower Unit
« Reply #5 on: March 18, 2011, 03:12:15 PM »
Yes, gear oil can pressurize as it gets warmer, this also can cause the gear oil to leak out of a seal. Gear oil in the drive bellows is not good and indicates a bad seal in the upper yoke carrier or a groove has worn into the seal face on the yoke shaft, they should be checked and replaced if needed.
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1967 V174 Crestflite SuperSport Modified
1987 Mercruiser 190 3.7LX/Alpha One

1970 V176 Swinger
1983 Mercury 115

Offline Tonka Jim

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Re: Lower Unit
« Reply #6 on: March 18, 2011, 04:18:34 PM »
Quote from: Rich_V174SS on March 18, 2011, 03:12:15 PM
they should be checked and replaced if needed.

I have the my lower units pressure tested every season.
it's cheap & good insurance!
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1977 SSV-176 / '85 115 Merc. - Mine
1989  CV 23 / 350 - 270hp - Kelly's
1968 V-174 / '73 140 I/O - Gifted to Son
1971 Seaking 14' / 1958 Evenrude 7.5 - Gifted to Grandson

Offline Hyperacme

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Re: Lower Unit
« Reply #7 on: March 18, 2011, 04:23:36 PM »
Never seen or heard of that ...
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