Engine trimming down on its own while driving on trailer.

[jrbdad]

While putting boat on trailer Saturday we noticed the engine would go down on its own when powering onto trailer. It will trim up find when running down lake and does no appear to go down on its own when running. I checked the fluid and it was at correct level. It did it again an Sunday. We are not doing anything different then we have done for the over 3 year i have owned the boat. Matter of fact the ramp we used this weekend is better and i have trailer little deeper then normal. So it should have went on easily.

Did some reading and found a thread on SB 2017-012 (Check Valves). This sounds like it could be cause of my issue.

I never leave the engine up with out trailering support so i do not know if it leaks down when sitting.

2017 PRO Xs 115 ct 2B484135

Thanks

[jrbdad]

Any help would be appreciated.

[Mechanic Bob]

Check the manual trim screw. Maybe loose?
Other than that, I would raise and lower it while on the trailer. Maybe drain and replace the fluid. Just my 2 cents

[blackwater]

Mine has done this from day one.

[jrbdad]

Mine has done this from day one.

It should not do that.

[jrbdad]

Check the manual trim screw. Maybe loose?
Other than that, I would raise and lower it while on the trailer. Maybe drain and replace the fluid. Just my 2 cents

I will look at that. When we raise it to install support for trailering it stays in place so i think it is probably good but will check.
Thinking it has to be bypass valve or internal seal.

[Rick H]

I'm pretty sure if you are on the lift cylinder and not the trim cylinders its normal for it to trim down on throttle until it reaches the trim cylinders. Once it reaches the trim cylinders then they shouldn't allow the motor to trim itself further down.

[jrbdad]

Pretty sure 115 only has 1 cylinder. Now it does have a range for tow but will not raise that high while engine is running.

We have not changed anything we do loading the boat. It will go ALL the way down when powering on trailer. Not just lower a little.

[Rick H]

Maybe true never had a merc that small but the 90 rude is a 3 ram for what its worth.

[jrbdad]

Crazy think is we bring motor up to same spot and it have never done this. I guess it would be possible that the ramp we were using last weekend was steeper then we usually us? I guess i will try it again at different ramp and see what happens.

[EuropeanAM]

Blackwater- appreciate the helpful info but do keep in mind we should have only ONE (1) engine in the post. Thanks!

jrbdad: The explanation in that email is a little misleading as the "computer" doesn't raise or lower the trim under any circumstances on this engine model.

Engine may be forced down due to the relief system, and engine RPM's may be limited due to trim being too high.

Let's check for leakdown: Raise the engine up and place an object below the bullet of the gearcase (a 5 gallon bucket, upside down works nicely). Set trim angle to 2" above the bucket, and allow it to sit that way for 12 hours (overnight).

Does the gearcase drop to rest on the bucket? If not, how far above the bucket did it remain?

[jrbdad]

Thanks, I was unsure of that info. I will give that a try tonight.

[jrbdad]

So let it sit for 9 hours or so and it dropped MAYBE 1/8 inch. Will let it set while at work today and check it again.

[EuropeanAM]

Unless you see a considerable drop (compared to above), what you're experiencing is likely the NORMAL operation of the trim system.

[blackwater]

jrb did you take it to the dealer.Like to here what they had to say.

[Dam0007]

It’s normal. Did it on my 2 stroke and the new 4 stroke as well. It also won’t let you trim up into the tilt section while on pad.