Mercruiser Trim Issue - Stopping at 3/4 Down

1993 Sea Ray 170 w/ Mercruiser I/O 3.0L Alpha 1

Hi guys. I've done some research, but cant find a definitive answer and thought I'd put it out there to get a second opinion before I dive into this project. This time last year I had the shift interrupt cable replaced by a professional boat mechanic, ever since, my sterndrive will not trim all the way down. According to the gauge it stops at or just before 3/4 down.

When it's just me or one other person on the boat I have no problems, but when I have a group on the boat it takes it a while to plane out. Is this a problem with air in the line or could the trim switches been improperly adjusted during the prior prior repair?

Thanks in advance for your help!

FYI - The up and down and trailer on my switch work with no issues.

Re: Mercruiser Trim Issue - Stopping at 3/4 Down

Additional information from an email with a different local mechanic:

On Tue, May 1, 2012 at 4:39 PM, Service wrote:
Hi Brian,
Ignore what the gauge is indicating. If the trim sender is bad, the gauge will not read correctly. It is possible that the prior dealer did not adjust the trim gauge sender correctly. Nothing in the trim sender affects if the drive goes all the way down. Trim the outdrive down all the way as far as it will go and make sure the hydraulic rams are being fully retracted to tuck the outdrive under the boat for helping get the boat on plane. It is normal for the boat to be harder to plane off with a much heavier load than 1 or 2 people. The more load you put into the boat the harder the engine has to work. You may need to get a 2" lower pitch prop to run when you are going to go out with a heavy load and your current prop for when you only have a light load in the boat.
Thanks,

Service Manager

My reply:
Thank you for your quick reply! I understand it's harder for the boat to plane out with a load of people in it, but I have had the boat for 3-4 season's prior to this (with the same prop) and it was never this extreme. I don't believe the senders are bad because both the up, down and trailer buttons work just fine.

I will double check and see how far down the motor is extended when I have it down as far as it will go.

Re: Mercruiser Trim Issue - Stopping at 3/4 Down

Yes, like the man said, take a look to see if the outdrive is actually going down all the way. Then, you'll know if it is a gauge issue or a trim/outdrive issue.

But, don't you just love it when a boat shop fixes one thing and your boat comes back with another problem :facepalm:

Re: Mercruiser Trim Issue - Stopping at 3/4 Down

Why didn't you take it back to the dealer that repaired it. It may have been as simple as they forgot to set the gauge sender, the could have adjusted it for you and you would be set to go. It only takes a few minutes to adjust.

Re: Mercruiser Trim Issue - Stopping at 3/4 Down

So I jacked up the trailer on some blocks yesterday and lowered the sterndrive, it actually went a little beyond vertical like it should and then by a random chance the gauge actually read that it was all the way down! I really wanted to but didn't have time to go drop it in the water and see if I would have the same results. This was the first time I've seen it peg all the way down in about 15 runs.

Does that even make sense that would happen out of the water?

Don - He is a terrible mechanic that I don't plan to go back to. I mentioned to him when I took it in later and he half acknowledged it and obviously didn't take a look at it. Every time I go to his shop he is playing around rather than working on the 20 or so boats he has sitting in his yard.

Re: Mercruiser Trim Issue - Stopping at 3/4 Down

thechamper said:

So I jacked up the trailer on some blocks yesterday and lowered the sterndrive, it actually went a little beyond vertical like it should and then by a random chance the gauge actually read that it was all the way down! I really wanted to but didn't have time to go drop it in the water and see if I would have the same results. This was the first time I've seen it peg all the way down in about 15 runs.

Does that even make sense that would happen out of the water?

Don - He is a terrible mechanic that I don't plan to go back to. I mentioned to him when I took it in later and he half acknowledged it and obviously didn't take a look at it. Every time I go to his shop he is playing around rather than working on the 20 or so boats he has sitting in his yard.

Click to expand...

Ayuh,.... Trim gauges are like fuel gauges in boats,....

Notoriously Inaccurate...

Get to know how to drive yer boat, 'n you won't need a trim gauge....

Re: Mercruiser Trim Issue - Stopping at 3/4 Down

Yeah I know my fuel gauge hasn't worked since I got the boat...I gave up trying to fix it.

Again, I don't think this is an issue with the gauge acting up, I believe there is a separate issue as I have driven this boat for five summers now and know how it drives. Last summer was the first time she couldn't get up out of the water fast enough to pull a wakeboarder out of the water fast enough...same group of people on the boat, same amount of junk in the boat, same driver....

Re: Mercruiser Trim Issue - Stopping at 3/4 Down

Last summer was the first time she couldn't get up out of the water fast enough to pull a wakeboarder out of the water fast enough...same group of people on the boat, same amount of junk in the boat, same driver...

Click to expand...

If you was going only by what the gauge said and nothing else, then that explains why it didn't work so well.