Mercruiser Alpha One Trim Won't Work

E36 Phantom

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Jun 11, 2012
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1991 SeaRay 170 w/ 3.0L I4 and MerCruiser AlphaOne outdrive

Just bought the boat, this is our first time out in the water with it, and the trim worked fine in the driveway on muffs, and out in the water all day. Came back to load up on the trailer and got nothing. Relay clicked for each switch (trim up/trim down/trailer) but absolutely no movement any direction, up or down. This was with a brand new battery that turns over just fine, with the engine stopped and running, in neutral, forward, and reverse. Fluid in the reservoir looked fine.

Any ideas for what to look for? It's still at the marina waiting for their "mechanic" :)eek:) to look at it, but I want to make sure I get the straight scoop from him.

Thanks all!
 

Bondo

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Re: Mercruiser Alpha One Trim Won't Work

Ayuh,... Could be corroded wiring ends, or a bad trim motor...
 

E36 Phantom

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Re: Mercruiser Alpha One Trim Won't Work

Thanks for the reply. Is there any manual release on the outdrive, so I can lift it in the trailer mode to get home and troubleshoot?

Also, do the motors typically fail without warning?
 

Don S

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Re: Mercruiser Alpha One Trim Won't Work

No manual release. Just disconnect the trim cylinders from the back of the drive and lift the drive.

Do you have an Alpha I or an Alpha I Gen II drive. being a 91, it could be either.

Assuming the trim motor itself didn't fail, get a couple of jumper wires and jump the Blue wire to the trim motor on the positive terminal of the battery and the black wire to the negative terminal of the battery, that will raise the drive.
 

E36 Phantom

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Re: Mercruiser Alpha One Trim Won't Work

D'oh. Three guys standing there staring at it and none of us thought to unbolt the hydraulic cylinders. Thanks, seems too obvious now!

Unfortunately, I've only owned European cars so most all my tools are metric, and the boat isn't with me of course. Would anyone happen to know the size of the bolt and nut (I'm assuming they're SAE) so I can borrow the right sized wrenches before I head down there?

The mechanic called and says he ran a couple quick tests and believes it's the pump. Not having a history with the mechanic I'm always a little skeptical when they jump to the most expensive part, but are there any recommendations for good brands and ones to avoid? I'm also tempted to go used... thinking about just towing it home and DIYing it. Can't be that hard, right? The thing looks pretty easy to get to.

Edit - I think it's a GenI - I only recall seeing AlphaOne logos on it, and I'd assuming GenII branding would be pretty prominent on an early production of a new upgraded unit.
 

fat fanny

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Re: Mercruiser Alpha One Trim Won't Work

I highly suggest diy get the merc service manual for your drive post serial # off drive and some will send you a pdf link. troubleshoot before spending any money. It will save you money if your mechanically inclined it's not that hard. Good luck and post back!
 

rickryder

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Re: Mercruiser Alpha One Trim Won't Work

I think 9/16" or 5/8" on the nut size = 14 15 16 mm
 

E36 Phantom

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Re: Mercruiser Alpha One Trim Won't Work

You guys are awesome. I talked to the mechanic and am going to pick it up tomorrow night so I'll have more info then.

I've read about the failing contacts inside the motor and such, but I found an aftermarket one for $55 new, rather than wasting time fooling around I'm tempted just to buy it and replace it. It doesn't look like replacing just the motor is too hard. With that in mind, one last "uninformed" question:

According to the iboats part xref (here), it looks like most modern MerCruiser outdrives used the following OEM part #s: 17649, 17649A1, 17649T, 87828, which xref with Sierra motor 18-6772. By extension, on Pat's Small Engine Parts (here, scroll down some), aftermarket part AHTRM0008 xrefs with the Sierra part 18-6772 and the OEM parts listed earlier, so theoretically I should be able to separate motor and pump and replace just the motor with AHTRM0008 for $55, right?
 

Bt Doctur

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Aug 29, 2004
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19,093
Re: Mercruiser Alpha One Trim Won't Work

in that link you remove 2bolts(screws) #21.removes motor from pump body
 
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