Mercruiser Trim Issue (not the usual issues)

[RBuffordTJ73]

I have a 2018 Chaparral with the 6.2L engine and Bravo 3 outdrive. I am having a kind of unique problem.
If the drive is trimmed all the way up, it will not trim down, it engages the trim motor and the pump is running but the drive will not move (not a Relay/Solenoid issue) If I don't trim it all the way up it operates normally up and down, the problem shows when the drive has gone all the way up, then releasing the pressure from the trim lines is the only way to get it to come back down.
Anyone else run into this or have any ideas? I appreciate the time you out into reading that.
Rick

 

[Bondo]

Ayuh,...... Welcome Aboard,...... 2 possibilities come to mind,.....
If yer in the salt, or brackish water, corrosion can build up around the shaft, by the seals, causing a bind,....

The other is, in the pump, when you raise it full up, you hear the motor load up, when that happens, tap the down button a couple of times to unload the pump, 'n it's valves,.....
Leaving it full hard up, can cause that locking valve to deform, hang, or just go bad,....

The trim pump makes 'bout twice the up pressure, vs; down pressure,....

 

[RBuffordTJ73]

No salt or brackish water here all mountain lake water but good idea. As for the other I tried tapping away but no go, she is holding tight in the up position. I was thinking maybe an internal hydraulic issue in the system somehow and you may be on to it, but not sure so keep the ideas flowing I really appreciate it.

 

[Fun Times]

Does the drive get stuck right away or after some time once it reaches full trailer mode?

Being an 2018, has this been doing it awhile now or all of a sudden?

Are you able to (try to) have someone help push down on the drive as someone starts the down button to see if it will free up?

Is the boat in the water?

Could try removing the trim cylinders from the drive on at a time and see what one seems to get stuck.

Having/using your stern drive / transom serial numbers is best for finding your exact parts but you might need to open up the cylinders for inspection / cleaning... maybe there's an issue with the scraper rod item 16 or cap end 'item 21 for examples, https://www.mercruiserparts.com/bam/subassembly/30974/11210/150

Any recent service work done to mention and now the issue?
Make sure the rear pivot ends are positioned as shown below.
Page 20, http://www.boatingwithtr.com/Members/PDFs/5b_28.pdf
Page 32, https://fliphtml5.com/cdmd/lfie/basic


Or maybe just don't go all the way up. https://www.ebay.com/sch/i.html?_fr....l1313.TR0.TRC0.H0.TRS0&_nkw=15768A3&_sacat=0

Trim Cylinder Spacer Kit Prep

All, I need to install trim cylinder spacers in the rams of my Alpha I to avoid it hitting my swim platform when raised up and have questions: 1. Will one set of spacers be sufficient or do I need to order more to stack spacers in the cylinder? 2. Do I need any special wrenches? I saw a...

forums.iboats.com

 

[RBuffordTJ73]

Does the drive get stuck right away or after some time once it reaches full trailer mode?

Being an 2018, has this been doing it awhile now or all of a sudden?

Are you able to (try to) have someone help push down on the drive as someone starts the down button to see if it will free up?

Is the boat in the water?

Could try removing the trim cylinders from the drive on at a time and see what one seems to get stuck.

Having/using your stern drive / transom serial numbers is best for finding your exact parts but you might need to open up the cylinders for inspection / cleaning... maybe there's an issue with the scraper rod item 16 or cap end 'item 21 for examples, https://www.mercruiserparts.com/bam/subassembly/30974/11210/150

Any recent service work done to mention and now the issue?
Make sure the rear pivot ends are positioned as shown below.
Page 20, http://www.boatingwithtr.com/Members/PDFs/5b_28.pdf
Page 32, https://fliphtml5.com/cdmd/lfie/basic
View attachment 377038

Or maybe just don't go all the way up. https://www.ebay.com/sch/i.html?_fr....l1313.TR0.TRC0.H0.TRS0&_nkw=15768A3&_sacat=0

Trim Cylinder Spacer Kit Prep

All, I need to install trim cylinder spacers in the rams of my Alpha I to avoid it hitting my swim platform when raised up and have questions: 1. Will one set of spacers be sufficient or do I need to order more to stack spacers in the cylinder? 2. Do I need any special wrenches? I saw a...

forums.iboats.com

Q: Does the drive get stuck right away or after some time once it reaches full trailer mode?
(A) Immediately upon reaching full tilt (trailer mode)

Q: Being an 2018, has this been doing it a while now or all of a sudden?
(A) For a while, over a year

(Q) Are you able to (try to) have someone help push down on the drive as someone starts the down button to see if it will free up?
(A) Yes, no play or give at all when trying this.

Q: Is the boat in the water?
(A) No on a trailer

Could try removing the trim cylinders from the drive on at a time and see what one seems to get stuck.
(Reply) Yes may try that shortly.

Q: Any recent service work done to mention and now the issue?
(A) two technicians came put from the local dealer of this boat and released the pressure and said they could not figure it out so they told me not to put it into full tilt again to avoid the problem. Yes, seriously.

***Make sure the rear pivot ends are positioned as shown below.
(Reply) they are.

***Or maybe just don't go all the way up.
(Reply) I know right! LOL...may end up using the trim limiter to stop it from going full, stopping it just barely away from that.

Will keep you all updated as I go!

 

[stang32]

while you are activating the switch, have someone stand on the drive and bounce. if the drive frees up, it sounds like the cylinders are hanging up.

 

[RBuffordTJ73]

while you are activating the switch, have someone stand on the drive and bounce. if the drive frees up, it sounds like the cylinders are hanging up.

We did try that, I am just under 300 pounds and it didn't even wiggle.

 

[ROY WILLIAMS]

I have a 2018 Chaparral with the 6.2L engine and Bravo 3 outdrive. I am having a kind of unique problem.
If the drive is trimmed all the way up, it will not trim down, it engages the trim motor and the pump is running but the drive will not move (not a Relay/Solenoid issue) If I don't trim it all the way up it operates normally up and down, the problem shows when the drive has gone all the way up, then releasing the pressure from the trim lines is the only way to get it to come back down.
Anyone else run into this or have any ideas? I appreciate the time you out into reading that.
Rick

look up the drive trim cylinders of those switches ...
look up that voltmeter of the motor cyl ///....
the electrical motor is the internal issues of the corrosion ..

 

[04fxdwgi25]

Sometimes the little white plastic disc under the solenoid that can get a spec of material in it and prevent that solenoid from working. They pop right out and are easy to inspect.

 

[RBuffordTJ73]

Sometimes the little white plastic disc under the solenoid that can get a spec of material in it and prevent that solenoid from working. They pop right out and are easy to inspect.

Under the Solenoid? Do you mean under the pump?

 

[dubs283]

Sometimes the little white plastic disc under the solenoid that can get a spec of material in it and prevent that solenoid from working.

OPs first post mentions the pump working both up and down. Can guess by this that most likely both solenoids and the pump are sound.

Based on info provided I'd suspect that one or both the rams have an internal issue or more likely one or more of the valves in the pump is sticking

 

[Scott Danforth]

the oildyne pump used in trim cylinder installations uses cross-port check valves for load holding. the down pressure is set to about 900 psi and the up pressure is just shy of 2500 psi. (because the area of the piston on the blind end is bigger than the rod end and the prop helps push the drive down).

because of this, the drive may get hung up if you mash the button and hold it until the pump grunts as there is not enough pressure in the down circuit to relieve the check valves

https://www.parker.com/content/dam/Parker-com/Literature/Hydraulic-Pump-Division/Oildyne-108-Series/02---108-165-Series-Section-12-2015.pdf

as @Bondo stated, once you get the drive up, immediately tap the down button once or twice to unload it.

dont raise the down pressure (which would alleviate the issue), as the aluminum gland could be blown off the cylinders.

 

[QBhoy]

@Bondo is spot on in my opinion. Been around hydraulics all my working life. First thing I had drummed into me as a junior engineer, was to never leave a ram at either of its extreme limits of travel. Always back her off a nudge the other way. Offers a little sympathy to the components, ram surface finish and seals.