Bravo III Losing Gear Oil In Bilge

[onsiteservice]

2001 Chaparral MCM 350 Mag Engine Ser# 0M029132, Drive Ser# 0M107260. Gear oil laying in the bottom of the boat, from what I can see it appears to be leaking back through the flywheel housing, the line and fitting are dry. I removed the drive and the input shaft bellow was completely full. A few questions,

1. The only place that I could see where drive oil could enter would be from the input shaft seal....I assume...but then again the first three letters of assume.

2. I removed the inspection cover from the top of the drive unit, assuming (again with the assuming) that the snap ring comes out, gear and needle bearing pull off (?) and there must be a snap ring holding the input gear on as well as another bearing. Then does the input shaft pull out? I did not see a snap ring on the outer side of the input shaft. Also on assembly does the top cover set the bearing pre-load on the top gear? If so, torque specs?

3. Could I be wrong and gear oil is entering another way?

I haven't ran into this before and thought I would ask rather than tear down something for no reason. I have looked through the site forum as well as the adult only sticky and couldn't really find what I was looking for.

Thanks in advance for the info!

 

[Don S]

Re: Bravo III Losing Gear Oil In Bilge

Pull the drive and look for gear lube in the ujoint bellows.

2. I removed the inspection cover from the top of the drive unit,

That is not an inspection cover, get new orings and put it back together. No, the top cover doesn't set preload. Bolts are 18 - 22 lb. ft.

 

[onsiteservice]

Re: Bravo III Losing Gear Oil In Bilge

Yea the drive is removed and sorry I called it the input shaft bellow but u-joint bellow is where the oil is located. As far as O-rings in the top cover there were non just a gasket.

So where the output shaft comes out of the unit, is there an o-ring there I'm assuming? If so I did not see a snapring of anykind to remove the output in order to install a new O-Ring. Is this the only place it could be leaking from beings the u-joint bellow was full? Thanks again

 

[Don S]

Re: Bravo III Losing Gear Oil In Bilge

Yea the drive is removed and sorry I called it the input shaft bellow but u-joint bellow is where the oil is located. As far as O-rings in the top cover there were non just a gasket.

Items 7 and 15 are for the top cover

Yes, the input shaft seal is the only seal that will cause oil in the bellows.

You want manual #28 for that drive. http://boatinfo.no/lib/library.html

 

[onsiteservice]

Re: Bravo III Losing Gear Oil In Bilge

Thanks DON! I was sure that's where it was coming from, but having you confirm it makes me feel a lot better! Have a good evening and thanks again!

 

[onsiteservice]

Re: Bravo III Losing Gear Oil In Bilge

So when I went to the dealer to pick up parts today I was talking to one of the mechanics about setting the torque and bearing crush. According to what I saw in the book for a Bravo III was a dial indicator and torque wrench. The tech goes on to tell me that you have to take top gear set out, remove back cover and install output shaft in the housing. Then set rolling torque, anyone else done this before? Also, wouldn't the way the book (#28 Mercruiser Manual) be how they want it set? Thanks for a quick response trying to get this thing together tonight!

 

[Don S]

Re: Bravo III Losing Gear Oil In Bilge

He may not have realized your drive was newer. With your drive, you have to put a hose clamp around the bearings to keep them inline with each other, the way you do it for Alpha drives (not really clear in manual #28). With the older model drives, the bearings were different size and you did have to use the housing to keep them centered to set rolling torque.

 

[onsiteservice]

Re: Bravo III Losing Gear Oil In Bilge

Thanks again for the quick response Don, two questions reading thru the manual again I saw that the nut should be torqued to 6 to 10 inch pounds, seems awful light but then again I'm used to building rearend gears. Also for the hose clamp do you center the clamp on the two races inorder to keep them centered I'm assuming. Thanks again Don!

 

[onsiteservice]

Re: Bravo III Losing Gear Oil In Bilge

I just did the conversion on that and it would be less than 1 ft lb? I have to be reading that wrong....right?

 

[Don S]

Re: Bravo III Losing Gear Oil In Bilge

Also for the hose clamp do you center the clamp on the two races inorder to keep them centered I'm assuming.

That's it does.

I saw that the nut should be torqued to 6 to 10 inch pounds, seems awful light

That is the rolling torque (bearing preload), not the torque of the nut. You need to tighten the nut tight enough to get the rolling torque between 6 and 10 in lbs.