Bravo 3 loss of lube oil - slowly then rapidly x2

[gcarmich]

I have a Bravo 3 outdrive. I recently replaced my lower unit. While I was out slow cruising, I got a low lube alarm. I checked the reservoir and it was down slightly so I filled back up to the line. I anchored out that night and checked the lube level in the morning and discovered that the lube tank was empty. I refilled and made my way back to the slip (1.5 hr trip). I experienced no alarm but after docking the boat, the alarm went off and I saw a slick on the water. I checked the lube reservoir and it was empty again. The bilge is still clean so the lube oil must have been lost outside the boat. Any thoughts on what could cause this erratic behavior?
Thanks,
Gil

 

[dubs283]

Could be gear lube monitor system fittings, hose, o ring at the bell housing or seal(s) in the drive

Boat needs to come out of the water to inspect properly

 

[Scott06]

I have a Bravo 3 outdrive. I recently replaced my lower unit. While I was out slow cruising, I got a low lube alarm. I checked the reservoir and it was down slightly so I filled back up to the line. I anchored out that night and checked the lube level in the morning and discovered that the lube tank was empty. I refilled and made my way back to the slip (1.5 hr trip). I experienced no alarm but after docking the boat, the alarm went off and I saw a slick on the water. I checked the lube reservoir and it was empty again. The bilge is still clean so the lube oil must have been lost outside the boat. Any thoughts on what could cause this erratic behavior?
Thanks,
Gil

You need to pull the boat before you get water in drive.

When u say lower unit was replaced you you mean the lower half or the complete outdrive

 

[alldodge]

Agree with Dubs, it leaking that much I would look at the hose and fittings between transom and drive
https://www.mercruiserparts.com/bam/subassembly/30971/952/180

 

[Scott Danforth]

You have a leak

Pull the boat and fix

 

[gcarmich]

I pulled the boat. I noticed a slight oil stain on the area where the bell housing meets the drive gear housing. The hose from the transom to back of bell housing shows no obvious leaks or damage. But I did find lube oil in the bilge - I traced the hose from reservoir to the transom and all looks good. I'm going to try some pressure testing to try to find the big leak.
Questions
1. Does the lube system build up pressure when the drive is turning?
2. Does the reservoir just serve as a gravity refill for the lube system?
3. Does the lube oil circulate through the system?

Thanks,
Gil

 

[alldodge]

1. Yes
2. Yes
3. No
Your seeing lube in the bilge and on the transom assembly, it's the fitting that goes thru the transom

 

[gcarmich]

If it's on both sides, would water be coming in through it?
How can I test it and what would the fix be?

 

[Scott06]

Would also check input shaft seal is not leaking lube into the bellows and eventually the bilge

 

[alldodge]

You can pressure test but don't use much pressure, maybe 5 psi or so with a hand pump

If thee feed thru is high enough probably not

The fix is replace the fitting item 1
https://www.mercruiserparts.com/bam/subassembly/30972/1943/330

 

[gcarmich]

I found one problem - fitting 10 (quick connector to the transom passthrough) was cracked. I believe that was the source of the lube oil dump into the bilge. I replaced it and pressure tested from the reservoir hose end to a hose pliers clamped outside - between the transom and the bell fitting. It held pressure without issue.
I left the hose pliers in place and pressure tested from the the oil filler on the gear casing and found that the pressure dropped quickly. I sprayed soapy water on the mating area between bell housing and gear casing and the gear casing and lower unit and saw no bubbles. I installed a new SEI lower unit last season so I am guessing the shaft seals are good.
Where should I test next and how? Soapy water on the back side of the bell housing? Should I pull the props and spray soapy water on the seals? I'd prefer not to have to pull the outdrive apart in not necessary.

 

[dubs283]

At this point you need to remove the drive from the bell housing and pressure test it separate from the lube monitor system

Check to make sure the o ring is seated properly in place at the lube monitor valve in the bell housing once the drive is removed

 

[gcarmich]

I was afraid of that. It is so difficult to pull the gear housing off the bell housing. Are there any tips on getting the two apart?

 

[gcarmich]

I got them apart. Does the gear housing automatically seal the lube system when separated? Does bell housing end lube line also seal automatically?

 

[04fxdwgi25]

1. Yes
2. Yes
3. No
Your seeing lube in the bilge and on the transom assembly, it's the fitting that goes thru the transom

Some how I lucked out. My thru transom fitting is brass or bronze.

 

[gcarmich]

After separation, I pressure tested from the reservoir end and it held. So it looks like all lube system is good thru the bell housing. I noticed that lube oil is dripping where the drive shaft goes into the bell housing. I pressure tested (10psi) and sounds like air is coming from the drive shaft area (I only separated gear housing and bell housing about an inch. Now I'm suspecting the upper gear drive shaft seals are bad. That the bilge lube oil is from a drive shaft seal leak. Does that sound reasonable?

 

[Scott06]

After separation, I pressure tested from the reservoir end and it held. So it looks like all lube system is good thru the bell housing. I noticed that lube oil is dripping where the drive shaft goes into the bell housing. I pressure tested (10psi) and sounds like air is coming from the drive shaft area (I only separated gear housing and bell housing about an inch. Now I'm suspecting the upper gear drive shaft seals are bad. That the bilge lube oil is from a drive shaft seal leak. Does that sound reasonable?

yes very common your bellows will be full of drive lube then

 

[gcarmich]

Sounds about right. Is it a big fix?

 

[gcarmich]

Is the bellows sealed at the transom? If so, how did the bilge get loaded with lube oil?

 

[alldodge]

The drive seals water out but does not keep lube out of bilge. With the drive shaft seal leaking it will fill the upper bellows and the start leaking into the bilge,

Need the drive shaft removed to replace seals
While your at it check tolerances to make sure they are in spec.