Mercury 9.9 lower unit vent hole leakage

[CaptTorS]

I bought new seals/washers for both drain& vent holes, when I seem a little oil running down out of vent hole after boating. Put in some more oil til it came out top, using a pump, and put new bolts & washers on, tight. Came back a minute later & oil is running down side again. Anyone know what's wrong? Too much oil? Thanks

 

[Mi duckdown]

Re: Mercury 9.9 lower unit vent hole leakage

make sure there is not any of the old seal/washer stuck on lowerend case. use a small screwdriver or pick and scape it.

 

[CaptTorS]

Re: Mercury 9.9 lower unit vent hole leakage

make sure there is not any of the old seal/washer stuck on lowerend case. use a small screwdriver or pick and scape it.

Yes, I made sure, I scraped it out and made sure there was a good clean seat for the washer. How can oil suddenly appear after that? Is there pressure build up when not running?

 

[CaptTorS]

Re: Mercury 9.9 lower unit vent hole leakage

I was going to post an update to the situation, but I see that would be pointless

 

[snowman48047]

Re: Mercury 9.9 lower unit vent hole leakage

Not much that can be wrong other than what was posted, a bolt in a hole with a seal. I had one the threads were stripped, so it leaked. What did you find?

 

[CaptTorS]

Re: Mercury 9.9 lower unit vent hole leakage

Not much that can be wrong other than what was posted, a bolt in a hole with a seal. I had one the threads were stripped, so it leaked. What did you find?

I haven't found why for sure yet, but I did tighten far tighter than what I felt was necessary or safe, and it did not leak. I really don't think it should have to be that tight.

 

[gonogo]

Re: Mercury 9.9 lower unit vent hole leakage

Need to be very tight on new gaskets, they are hard, not soft. On my 9.9 I changed oil once and bought new gaskets, the old looked good so I used them over, no leaks.