MC1 Outdrive needs help to go down

[Piratehooker]

Sorry if this has been addressed here before, but I couldn't find it. I have a 78 Searay with a 302 and a MC1 drive. Ever since I got it the down has not worked so well on the trim. It goes up just fine, but sometimes I have to stand on the drive to get it to go down under its own power. It will work sometimes, but only after I have cycled it back and fourth a few times. It has the three button style switch. -Thanks

 

[Don S]

Re: MC1 Outdrive needs help to go down

If the boat has been used in salt water, it's a good chance you have corrosion build up where the rod from the trim rams come out of the trim cylinder.
They make kits for them, if you can get the old ones apart.

 

[achris]

Re: MC1 Outdrive needs help to go down

What happens is the outer most seal in the end cap leaks and allows water into the end cap. Because of the other seals lower down this water doesn't make it into the hydraulic fluid, but it does sit inside the end cap and start corroding it. As the end cap corrodes the aluminium expands and 'grabs' the trim ram rod. As the UP pressure is much high than DOWN and the surface area of the piston is more, the force exerted by UP can overcome the resistive force of the expanded end-cap, DOWN can't. You standing on the drive to get it down adds that little bit extra...

I have tried many different methods of repair, and the only successful one it to replace the end cap with a new one, complete with all new seals (they come already with the seals installed)... If you can get the old ones off.... That's where the fun is....

New end cap part number -> -45523. Unfortunately that now supersedes to a complete tube assy, and it ain't cheap....

Chris.....

 

[Piratehooker]

Re: MC1 Outdrive needs help to go down

Any chance at getting the old caps off and fixing them? I have a lathe? But you have at least put me in the right direction. I may also try and get a set of rams from feebay or something like that. UPDATE I found the caps PN45523 on ebay for $8.99 NOS so grabbed a pair, thanks for the advice.

 

[MarkSee]

Re: MC1 Outdrive needs help to go down

What happens is the outer most seal in the end cap leaks and allows water into the end cap. Because of the other seals lower down this water doesn't make it into the hydraulic fluid, but it does sit inside the end cap and start corroding it. As the end cap corrodes the aluminium expands and 'grabs' the trim ram rod. As the UP pressure is much high then DOWN and the surface area of the piston is more, the force exerted by UP can overcome the resistive force of the expanded end-cap, DOWN can't. You standing on the drive to get it down adds that little bit extra...

Always wondered what was happening in there. That's quiet a good explanation there mate; even I:facepalm::facepalm:understand it.

Mark

 

[Piratehooker]

Re: MC1 Outdrive needs help to go down

Sorry guys, one more thing. When I was looking on ebay, the rams for my drive were referred to as fitting a pre-alpha drive. I always thought mine was an MC1. Are they the same? My SN is 4197680. I read a whole paper on this one time but was still confused. -Thanks

 

[Bondo]

Re: MC1 Outdrive needs help to go down

Sorry guys, one more thing. When I was looking on ebay, the rams for my drive were referred to as fitting a pre-alpha drive. I always thought mine was an MC1. Are they the same? My SN is 4197680. I read a whole paper on this one time but was still confused. -Thanks

Ayuh,.... You have an MC-1, there's No such thing as a Pre-Alpha....

Mercruiser has never sold an outdrive they called a Pre-Alpha drive...

The ebay seller don't know what he's talkin' 'bout....

 

[achris]

Re: MC1 Outdrive needs help to go down

I'll add to Bond-o's comment.

The phrase 'pre-Alpha' (really grits my tits!!) is used by some twit at boats dot net in their instruction on various aspects of this style drive. It is used to refer to any drive 'before Alpha One', which is 1985 and earlier. That covers no less than 3 different drives, MC-1, R and MR. The interesting thing is that the MR and the Alpha One have so much in common, more than the MC-1 and the R. Strictly speaking the term also covers TR, TRS, '0' drives and some SSM drives (Super Speed Master). That makes the term so redundant that the idiot who coined it should also be made redundant.

Chris.....

 

[Bondo]

Re: MC1 Outdrive needs help to go down

I'll add to Bond-o's comment.

The phrase 'pre-Alpha' (really grits my tits!!) is used by some twit at boats dot net in their instruction on various aspects of this style drive. It is used to refer to any drive 'before Alpha One', which is 1985 and earlier. That covers no less than 3 different drives, MC-1, R and MR. The interesting thing is that the MR and the Alpha One have so much in common, more than the MC-1 and the R. Strictly speaking the term also covers TR, TRS, '0' drives and some SSM drives (Super Speed Master). That makes the term so redundant that the idiot who coined it should also be made redundant.

Chris.....

Ayuh,.... 'n don't forget the As, Bs, 'n Cs,....

I think they were 'tween the Os, 'n the MC-1s...

 

[achris]

Re: MC1 Outdrive needs help to go down

Ayuh,.... 'n don't forget the As, Bs, 'n Cs,....

I think they were 'tween the Os, 'n the MC-1s...

Ah, yes, the EZ-Shift, 1964-1966... Yep, definitely 'pre-alpha'....

Oh, almost forgot the II and III drives and the 'E' (Electric shift) and 'H'(Hydraulic shift) drives too. 1962-1972... Still pre-Alpha.

So, I count no less than 16 different 'pre-Alpha' drives.... Good one boats dot net dot idiot!