Drive oil loss

[Intern8tion9l]

I've topped this thing off twice already this season, each time maybe 2-4oz. In this pic the level is right at the rubber securing strap, after roughly 6-8 hours of running. There isn't any oil sheen on the water around the back of the boat; I'm concerned as to where it all might be going

[Phillbo]

What kind of drive? BIII's have a tendency to 'burp' after being serviced and is normal to have to add fluid after a couple hours of use but if you have gone through half a tank in 8 hours multiple time you have a leak.

Is the bilge clean all the way to the transom?

[Intern8tion9l]

It's an alpha. I suspected some air bubbles the first time, maybe even the second....certainly not anymore. There is some dirty water in the bilge. It doesn't appear to have the amount of oil in it that this would produce, but I suppose cramming myself down alongside the engine to inspect the line would be a good step

[Phillbo]

They have a tendency to leak at the transom fitting but like you said, given the amount of lube you have added you would notice that in the bilge very easily.

Is the boat on a trailer? If so run it on the muffs and engage the drive to see if it only leaks when the prop is spinning.

[Intern8tion9l]

Still in its slip. Prob won't be on blocks till the end of October, but thank you for the suggestion

[mmwjr]

It may be a drive seal that is only leaking slowly when the prop shaft is turning so you may not see anything in the water. When you pull the boat drain the lube and look for water. When it's empty perform a pressure bleed down test to see if it holds pressure or not.

[Intern8tion9l]

Thanks, I'll do some research on that process. Maybe I'll even get lucky and find a leak in the line

[jrsick]

Your problem could be air bubbles, a leak, or oil shear. When did you last change your drive oil? If recently, then this could be attributed to air bubbles. If it's been a while then you may be experiencing oil shear. Have you been running the boat hard with water sports or high speed runs?

[Intern8tion9l]

Changed the oil in the spring before it went in the water. I don't do any water sports or tow anything. I've done 2 short wide open throttle runs just to make sure the prop was within specs. 99% cruising speed at 22ish mph

[Casey]

What is oil shear?

[shrew]

Originally Posted by Casey

What is oil shear?

It can occur with oil when it is subjected to mechanical stress, such as being run through gears in a transmission over a long period of time. The process breaks down the oil viscosity which essentially thins the oil.

It's one of the reasons we change oil on a regular basis.

I never thought of shear as decreasing in volume.

I usually have to top off my drive lube container twice a season. Usually toward the first half of the season. After that it seems to stabilize.

[Intern8tion9l]

I didn't have to touch it last season, which makes it more concerning

[shrew]

When is the last time you changed the bellows? There is a seal that self-lubricates from the drive lube, but is designed to suck the lube back into the drive. It one of the reasons water in the main bellows can work it's way into the drive.

Sometimes it pukes and can't all get sucked back in. You usually find a certain amount inside that main bellows as a result. I bet when you replace the bellows you'll find some of your missing lube.

[Intern8tion9l]

It's been a few years since they were replaced. I had the drive off at the beginning of this season and inspected them though