Overflowing gear lube reservoir

[Mark & Molly]

Folks, my B3 outdrive is losing gear lube from the engine reservoir tank cap. Last couple times out the reservoir leaked through cap onto bilge. Any thoughts on why would be appreciated. Reservoir cap is the small one on left in this picture with the red pin. Thank you!!

 

[Lazy Daze]

Under lot's of load or extended run time, the gear lube can heat up and expand. If it's being overfilled, then it will overlfow. Other than that, the next most likely cause is that water is getting in there. Get your service dep't involved - it's under warranty and if you haven't messed with the system, there should be no issue having this covered.

 

[radscoot]

Another possibility is that the cap is not on tight enough.

Mine was doing the same once in a while last season. Over the winter I pulled the bottle out and pressure tested with air in a bucket of water. What I found was that the bottle would leak from the cap if it was not on tight enough. Originally I was using finger tight. I found with my pressure test that I really had to tighten it hand tight to get it to stop leaking.

This season after 20 hours I have no more leaking of oil from the Bottle cap.

 

[Lazy Daze]

Just a side note regarding the bottles: Over time the fluid gets a little gunky/thick in the bottom of the reservoir. When I change drive fluid I always remove the bottle and spray it out with Brakleen. I'm not sure if the gunkiness adds to the rising fluid level, or not, but just in case...

 

[Mark & Molly]

I will try to tighten the cap this weekend. This may be it because I was just doing finger tight. Am I correct to assume that if I have a leak in an underwater seal that sooner or later I will have no gear lube in reservoir but just water? It's hard to see how water can get in but oil does not leave - if this makes sense.

 

[Wanderer 290]

Gunk in the bottom of the reservoir is the like culprit. O/d oil heats up, expands and then can not flow back in to the o/d. A couple cycles of that and an over flow condition occurs. Plus the o/d Oil level is getting lower inside the case. Clean the reservoir and service the o/d from the bottom up.

 

[Mark & Molly]

Is gunk at the bottom of reservoir likely on a boat with 109 hours? I had drive removed and serviced last year ad part of annual work, so just wondering.

 

[Wanderer 290]

Sure. How many years to build 109 hours. And oil has additives plus contaminates that settle in a matter or hours.

 

[Mark & Molly]

Well I got it new in May of 2017. Outdrive removed last year in July as part of annual maintenance so gear lube replaced at that time. It seems to me that gear lube contamination takes a few years of neglect. Replacing gear lube each should remove contamination. That said she does in salt water 24x7x365.

 

[Lazy Daze]

Well I got it new in May of 2017. Outdrive removed last year in July as part of annual maintenance so gear lube replaced at that time. It seems to me that gear lube contamination takes a few years of neglect. Replacing gear lube each should remove contamination. That said she does in salt water 24x7x365.

If I may, what are you basing that thought on?

Gear lube gunkiness can, and does, happen within a year - even on boats that are well cared for. It's one of the reasons that Merc suggests to change gear lube on a yearly basis. It is very common for me to see gunk year after year. Not always, but moreso than not. This is not just my boat(s), but also the friends/family/service boats that I work on.

 

[scoflaw]

The level of fluid in the bottle should be higher when the motor and drive are hot. When the boat is cold the fluid level should return to a lower amount. If the drive oil is not going up and down like that something is plugged up. There's a valve on the cap on the older models, not sure about yours

 

[Wanderer 290]

And if the reservoir is clogged a negative pressure condition may be created inside the drive as it cools which may cause water to seep in the drive.

 

[Mark & Molly]

Ok not sure if I replied to this thread after I ran the boat again. But I ran it in 90 degree plus weather for 3 hours of and no leaks. Will change gear lube and pull outdrive for a annual maintenance. I think removing some oil and tightening cap may have solved this one.

 

[Tshehidy]

Change the cap, faulty cap valve.