Trim problem with my 4.3L Mercruiser Alpha 1

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poleclimber63

Cadet
Joined
May 9, 2010
Messages
11
This last week the tarp came of my Maxum, I de-winterized and myself and the family spent this beautiful weekend on the Lake. Problem is the power trim is malfunctioning:(
Problem: Trim will operate "Down" but not "up". To raise the leg, operating the "trailer" button will work. The trim indicator shows "down" or indicates an incorrect position.
I have been told the trim "limiting switches" on the leg could be the cause (outside of an electrical problem). If these switches are defective, will I have to remove the leg to replace them? I'm wondering how BIG a job this may turn into...

concerned in Canada!
 
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MCNPathfinder

Petty Officer 2nd Class
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Jul 24, 2010
Messages
125
Re: Trim problem with my 4.3L Mercruiser Alpha 1

This happened to me with my Alpha 1 as well. I think there are some wires they run back to the sensors/limiting switches that get freyed and old with the drive going up and down. Mine were actually broken. From what my mechanic said, once you get the leg down low enough, pressing the trim up will bring it as high as possible without causing damage to components. Quite honestly, I don't think it would be that hard to replace those sensors. I can't see you having to remove the whole out drive. I had them do mine because they were already going to have it apart for the bellows. Sounded like the parts were about $100 and they charged an hour labor.
 
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poleclimber63

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Re: Trim problem with my 4.3L Mercruiser Alpha 1

Thanks for your response! When I get the chance, I'll prove the wiring to the shifter etc. and if that TOK, I'll see about replacing the limiters(with cable harness I'm sure)... I hope I'll be able to find them at a reasonable $$$, everything marine is hugely expensive and/or high import duties.... Thanks again!!
 
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choppywaters

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Apr 27, 2012
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127
Re: Trim problem with my 4.3L Mercruiser Alpha 1

when I took ours in to the dealer for a good look over he found the same thing, wires were frayed. He just taped up the old wires and he said he just spliced it right to the battery. Over the winter Im going to have them replace some rings and at that time we"ll repair it so that doesn't happen.
 
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Chris1956

Supreme Mariner
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Mar 25, 2004
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28,571
Re: Trim problem with my 4.3L Mercruiser Alpha 1

Pole, The Mercruisers have a trim limit switch under one of the covers (port or starboard), where the outdrive pivots. They are open to the water and are made of a copper disc and a copper pointer. They have some electricity passing thru them. Guess how long they last in saltwater, before they turn into green slime....
 
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MCNPathfinder

Petty Officer 2nd Class
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Jul 24, 2010
Messages
125
Re: Trim problem with my 4.3L Mercruiser Alpha 1

I think it's on the side that doesn't have the steering wheel. At least that's where my freyed wires seem to suggest it was connected to. Although I have those two round discs on each side of mine.
 
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poleclimber63

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May 9, 2010
Messages
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Re: Trim problem with my 4.3L Mercruiser Alpha 1

I can imagine what salt water does.... luckily my Maxum has never seen the salt chuck, however, the hard (high mineral content) we have in the lakes here in the west is definitely not easy on things.... According to a Merc manual I was able to get my hands on, from a bud at work, it shows that the leg should come off..... I might try the trick suggested by choppywaters until the Fall, when I can get it in the garage and do everything ie. water pump, seals, bellows etc. I see the trim limit switch is on the port side of the outdrive, and the position switch is on the starboard... appearently, the leg comes off to feed the wires through the outdrive and hence the transom opening to the hydraulic pump.... wow.
 
Last edited:
paultjohnson

paultjohnson

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Jul 29, 2010
Messages
1,560
Re: Trim problem with my 4.3L Mercruiser Alpha 1

MCNPathfinder said:
I think it's on the side that doesn't have the steering wheel. At least that's where my freyed wires seem to suggest it was connected to. Although I have those two round discs on each side of mine.
Click to expand...
Um... That would be the port side... On that side is the trim LIMIT switch. Stbd side had the trim INDICATOR to the trim gauge on the dash [ if so equipped ] Its relatively easy to change the switch,but to run the WIRES up thru the transom is a SOB, the drive has to come off. Iv repaired my wires a few times with liquid elec tape, and have had the switch full of water, rusty, cleaned that up and has worked also...
 
dockwrecker

dockwrecker

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Mar 10, 2006
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1,392
Re: Trim problem with my 4.3L Mercruiser Alpha 1

Merc says you are supposed to replace the switches and wiring through the drive and transom. I cheated 7 years ago by installing new switches and soldering my wire connections and burying the connections in silicone and shrink wrap where they came through the boot. I might be lucky, but mine still work perfectly.
 
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