Trim System Issue / Bravo 3 outdrive won't stay up

[tpenfield]

As I'm getting the boat ready for splash day in about 2 weeks, I have noticed that the Port Outdrive does not want to stay up . . . slowly lowering itself over the course of a day or 2 :facepalm:

I did some measuring over time yesterday, and it looks like the trim cylinders collaspe at about 1/8" every 1-2 hours.

This seemed to have come on recently, as I did not notice it earlier this spring. So, I did some obvious things, like check everywhere for leaks . . . no leaks found. Checked the fluid level . . . A-OK, no issues with the fluid. I ran it full up and down a few times, just to see if there was any air to purge. All of those things did not seem to make any difference.

So, I'm thinking that it might be some blow-by in the trim cylinder(s) or some backflow at the pump :noidea: I did some searching, here and on the web in general, and it looks like I should try to isolate the issue to either the trim cylinders or the pump.

So, I just want to check my approach and get any advise/comments:

1) I was planning raising and supporting the outdrive, then disconnecting the hydraulic lines from the pump and joining them together with a flare nut coupler, 'release' the outdrive from its support, and give it 6-8 hours to see if the outdrive lowers itself (this would mean trim cylinder issues)

2) If the outdrive were not to move during the 6-8 hours of testing, then I could assume it's a pump issue.

Does this approach seem about right? Anything else that I should do ?

My preference would be to have to fix the pump rather than the trim cylinders. . . but with my luck . . .

Engine and outdrive info is in my sig below . . . TIA.

 

[Don S]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

1) I was planning raising and supporting the outdrive, then disconnecting the hydraulic lines from the pump and joining them together with a flare nut coupler, 'release' the outdrive from its support, and give it 6-8 hours to see if the outdrive lowers itself (this would mean trim cylinder issues)

Should work.

 

[HT32BSX115]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

This seemed to have come on recently, as I did not notice it earlier this spring. So, I did some obvious things, like check everywhere for leaks . . . no leaks found. Checked the fluid level . . . A-OK, no issues with the fluid. I ran it full up and down a few times, just to see if there was any air to purge. All of those things did not seem to make any difference.

So, I'm thinking that it might be some blow-by in the trim cylinder(s) or some backflow at the pump :noidea: I did some searching, here and on the web in general, and it looks like I should try to isolate the issue to either the trim cylinders or the pump.

OR, you've been a bad boy and you used motor oil in the trim system


I am going to vote for a leaking check valve in the pump.....When I installed mine, I replaced them.

 

[Don S]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

I am going to vote for a leaking check valve in the pump.....When I installed mine, I replaced them.

He's not going by votes on what is wrong, he is wanting to know if his TESTING method will work or not.

 

[tpenfield]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

OR, you've been a bad boy and you used motor oil in the trim system

Actually, I have not needed to add fluid, since only owning the boat for a short while . . . but . . . I *thought* that the fluid was either 30 Wt oil or ATF and not to mix the two ??? :noidea:

 

[Don S]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

From the Bravo service manual.

 

[tpenfield]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

Don, how do you put together those thread specific graphics so fast?

 

[Don S]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

Don, how do you put together those thread specific graphics so fast?

Toys (aka Photoshop, Adobe Acrobat (not just reader) and Illustrator)

 

[HT32BSX115]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

He's not going by votes on what is wrong, he is wanting to know if his TESTING method will work or not.

I wuz kidding (of course!)

 

[tpenfield]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

UPDATE:

I raised and supported the outdrive, then tied the hydraulic lines together . . .


Then I removed the supports for the outdrive and monitored the trim cylinder extension length over the course of 7-8 hours. Previously, it would have collapsed about 1-2" during that time. Well . . . it did not collapse even 1/16" . . . Sooo, I am focusing on the pump as the source of the problem.

I guess I will have to read the maintenance manual to see how to repair the pump. I assume there is some sort of a check valve that may be getting some blow-by. this must be my lucky day, as I was hoping it would be a pump issue rather than a cylinder issue. I can fix the pump with the boat in the water . . . If it were the trim cylinders, then I would have to delay my launch, that is planned for Friday, or schedule a haul-out at some point. ($$$)

 

[tpenfield]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

OK, I have taken a look at the information regarding the trim pump that is in the Bravo Service manual. In terms of identifying and correcting the sources of a slow hydraulic leak, it looks like there is a 'shuttle' assembly that acts as valves for the main up and down hydraulic lines, as well as 2 pressure relief valves (up & down) and a thermal relief valve.

It looks like I could spend $300 +/- on buying rebuild/replacement kits for these parts. I am wondering if I should take the pump out for some disassembly and inspection to see if the source of the problem becomes more evident :noidea:

Pump is Oildyne Mercruiser #865380A13 (superceded from 14336A8) 1996 vintage.

 

[achris]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

Ted, The pump is a standard Oildyne 108 series pump. If you need parts, just go direct to Parker-Oildyne, bypass Merc and their 200%+ mark-up. I just replaced the reservoir on mine, cost $61 (from Parker) as opposed to $205 (from Merc) for the same item. It's probably only about $20 in the US. :facepalm:

 

[tpenfield]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

Thanks for the info. I will check it out. Kinds of reminds me of the $63 oil reservoir bottle from Mercruiser . . .

I made my own for $5 . . .

 

[achris]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

Love the colour...

 

[tpenfield]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

It fit perfectly . . .

 

[tpenfield]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

Looks like I can get a new motor/pump assembly for around $200 from DB Electrical. I've had good luck with them on alternators, etc. Then I can fix the original pump at my leisure and have a spare.

 

[saltydogjeff]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

I don't think the pressure relief valves or thermal relief valves would be cause for the leak unless they are cross connected back into the system. Relief valves usually drain out of the system due to pressure overload. Could save you some $$.

 

[tpenfield]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

I don't think the pressure relief valves or thermal relief valves would be cause for the leak unless they are cross connected back into the system. Relief valves usually drain out of the system due to pressure overload. Could save you some $$.

Yes, more likely the control valves within the pump body. By replacing the whole pump assembly both bases are covered. As far as rebuilding the 'spare', probably will just order the valve internal parts directly from Oildyne-Parker. May get the relief valves as well, if they are not too pricey.

 

[achris]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

With the amount of gear you've replaced and rebuilt the old one as a 'spare', you'll have a complete spare engine shortly...

 

[HT32BSX115]

Re: Trim System Issue / Bravo 3 outdrive won't stay up

Love the colour...

I love your spelling of "color" :thumb:

Yes, more likely the control valves within the pump body. By replacing the whole pump assembly both bases are covered. As far as rebuilding the 'spare', probably will just order the valve internal parts directly from Oildyne-Parker. May get the relief valves as well, if they are not too pricey.

My memory sometimes fails me but I seem to remember buying check (or relief) valves from a local Mercury parts source and they weren't a LOT of money. (I could be mistaken however)

I would not hesitate to buy another pump from an aftermarket source though..........lots on ebay too, new and used.....