Mercruiser Bravo 3 gear lube problems

[poliz296]

Hi I am new to this forum, but i have checked all preceding posts to see if my question was answered already. I have a 2000 mercruiser 5.7 with a bravo 3 drive. The drive seems to be pressurizing itself too much and blowing oil up the lines into the drive lube monitor(resevoir) the lube fills up the bottle then pours out the cap. The bottle is not leaking and there are no leaking lines. The cap is securely tightened and the level is correct. However this only happens while on plane or high rpm's when you back down the level lowers again

 

[Don S]

Re: Mercruiser Bravo 3 gear lube problems

That's due to heat buildup in the drive. Has the gear lube been replaced lately?<br />What is the water temperature where you are boating.<br />If you have warm water and a heavy boat, you may want to think about a drive shower to help cool it.

 

[poliz296]

Re: Mercruiser Bravo 3 gear lube problems

Thank you Don S., the water is approximately 80 degrees the boat is about 26 feet I have been looking into the driveshowers from and that seems to be the best answer for my problem I have had various problems with the drive: I have recently replaced the yoke seal and yoke due to a poor seating surface, found an exhaust shutter in the exhaust bellows, replaced both of them, replaced all bellows and water tube, replaced gimbal bearing and grease seal, replaced both u-joints, drained filled and pressure-vacuum tested the drive. I also replaced the outside gear lube hose and fitting, this is all due to barnacle growth and holes in bellows. Before this work the drive was pouring a lot of lube out now it is slower but not stopped. Do you think it could be from air pockets left in the drive from filling it (I filled it according to mercruiser specs.)? I did not notice any white deposits on the upper housing but I am fairly confident that you are correct, thank you very much. <br />Can you think of why it started doing this all of the sudden? I think it's because the engine overheated and melted that exhaust shutter (water flapper) and sent it to the bellows blocking the exhaust flow. Your opinion is greatly appreciated.

 

[poliz296]

Re: Mercruiser Bravo 3 gear lube problems

Do you think that the check ball in the Upper housing is bad? How about the gear lube valve in the bell housing?

 

[Don S]

Re: Mercruiser Bravo 3 gear lube problems

Those check valve are only to keep the gear lube from running out of the drive reservoir and drive when the drive is off. If you are filling the drive to Merc specs, you shouldn't have any problems with air bubbles.<br />With your overheat problem and the shutters blocking the exhaust, yes, that would cause a rise in temperature in the drive.<br />And with 80° water, yes you could use the drive shower.<br />Change your gear lube regularly. Heat is the worst thing that can happen to the lube.

 

[outboardguy]

Re: Mercruiser Bravo 3 gear lube problems

Take the cap off the bottle and inspect the inside.You should see a small rubber disk which is meant to let air into the bottle and not let the gear lube out.If it is damaged the expanding gear lube will just blow right by.

 

[muc]

Re: Mercruiser Bravo 3 gear lube problems

Also, make sure the o-ring is still in the cap of the drive lube monitor---it can fall out and cause your problem.

 

[poliz296]

Re: Mercruiser Bravo 3 gear lube problems

Thanks guys I will check the cap again for the O-Ring as well as the rubber disk. I am not sure if I saw that O-ring in there. Again I appreciate the help thanks.

 

[dmitchell]

Re: Mercruiser Bravo 3 gear lube problems

Bumping an old thread but It directly relates to my problem.

I have a 23.5 Trophy with 5.7L / Bravo 3 All weekend, I noticed that the lube reservoir was pressurized. We were 50+ miles from home and otherwise everything seemed fine.

Yesterday on the way home, cruising at about 3500 RPMs, the engine cutout down to 3000 then I chopped the throttle and it died. I restarted it and the noise was loud and not good....

Opened the cowling - The Lube reservoir had blown the lid off and was empty. Needless to say we got towed the remaining 25 miles home.

So anyone care to provide some in-site into how bad it might be?

Thanks,

Dave

 

[HT32BSX115]

Re: Mercruiser Bravo 3 gear lube problems

Howdy,


You may have a different problem not related to water temp..... If your boat sits in the water, you may have had water in the drive. When it started to warm up it may have pressurized the system and popped the cap.

Have you put it on a trailer and drained the drive lube yet? If you did how much lube did you get out and did it have water in it? How long ago did you change your drive lube?


Just as an aside, you might be better off starting a new thread instead of tagging onto an old thread like this.....


Cheers,

Rick

 

[dmitchell]

Re: Mercruiser Bravo 3 gear lube problems

Thanks,

The boat is normally trailered. I just bought it a month ago, the lube was fresh this spring probably has 50 hours on it.

I haven't had time to do anything other than get towed home and get the boat home. I'll work on it tonight.

I did grab the props and rotate them, it was really clunky and I have a sick feeling about it....

 

[HT32BSX115]

Re: Mercruiser Bravo 3 gear lube problems

Hi Dave,

Yeah, that doesn't sound very good if you're getting "clunky" when you
turn the props.


It really sounds like you had a drive lube leak that, after the drive pressured up allowed the oil to pump itself out before popping the cap.

I wonder if the drive was filled correctly by the previous owner........

I guess you should drain the oil and have a look but I think you know what you're going to find.....



Sorry about that...


Rick

 

[dmitchell]

Re: Mercruiser Bravo 3 gear lube problems

Morning!

Drained the oil last night and was surprised - no water at all. The oil was pretty black and I got about 1-1/2 quarts out of the drive. lots of small metal pieces though.

Pulled the caps off the top of the drive, from a laymans point of view, what I could see looked fine other than there being metal pieces in the oil. The upper gears looked great from what I could see.

I'm now suspecting that the lower unit overheated and cooked a bearing or something. If I grab the props, I can pull them forward about a 1/2" which I'm thinking points to lower unit problems.

Thoughts? I'm still waiting to hear back from a mechanic.

 

[HT32BSX115]

Re: Mercruiser Bravo 3 gear lube problems

Yeah,

If a bearing or gear any where in the drive started to disintegrate, that drive will have to be completely disassembled and all the parts inspected.


I am a little leery of the oil being really black after only 50 hrs.....It sounds like the previous owner maybe didn't change the oil only 50 hrs ago (or right before you got it)

It doesn't really matter. That doesn't really sound like an oil related failure unless it got really LOW and was ran that way......and then the failure mode is the bearings/gears that are oil starved, which are up-top.

It sounds like a rebuild might be in order. You can buy whole drives from ebay too...