1987 115 6 cyl. Power Trim Questions

[Raghauler]

SN 0B165923

Power Trim Design 2 (According to Mercury Service Manual 90-86134-4)

Picture: [img=http://img58.imageshack.us/img58/2708/outboardmerc115powertrixw0.th.jpg]

This has suffered from a very slow leak somewhere for a couple of years as the hydraulics would allow the motor to slowly fall after trimming up, although there was no visible evidence of a leak I could see.

After capping off the fluid and attempting to bleed, I was lowering the motor when it blew out and fluid poured out of it. It appeared to be comming from the underside of the port-side resevior - as though from the bottom of the main housing. I haven't removed the unit yet, so I can't see exactly where it failed.

Questions:

Is there a seal somewhere near the underside of the port-side reservior that might fail? The exploded parts diagram does not indicate one.

Is it likely it blew out the transom-side of the reservior cover and I just can't see it, or could enough pressure actualy crack the metal resevior (main)housing?

Where can I buy an entirely new assembly, or has Mercury discontinued manufacturing them?

New or used, what part can I specify (for an entire assembly)? How many years and models would suit my motor if I decide to look for a used assembly?

Thanks in advance for any answer.

 

[Raghauler]

Re: 1987 115 6 cyl. Power Trim Questions

Well, I can answer some of my own questions, so I might as well share since these vintage Merc's are still on the water, at least I still see quite a few.

They no longer make the same power trim unit, but Mercury does offer a replacement that my local dealer tells me will fit. Unfortunately, Mercury has fallen behind in production of them and they won't be delivering any until July 21 at the earliest. My dealer quoted me $1161.00 for the entire unit.

I was able to remove the assembly from my boat tonight (a somewhat involved task) and was relieved to see that the gasket between the reservior (main housing) and the reservior cover failed. The dealer said they still sell the gasket kits for these units ($18.42), so I should be able to fix this without too much expense.

I guess my only remaining question is: why did the gasket fail? Is there a probable reason the pressure was too much for it (failed check valve somewhere?) or was it simply too old? Could have I over-filled the reservior somehow? (I topped it off with the motor trimmed fully up just before it blew)

I don't want to reinstall the unit only to find a new gasket does no better than the old one did.