Trim Wanders Up Slowly (power off) O/W Normal! WHY??
07-26-2013, 09:37 PM
#1
Registered
Thread Starter
Join Date: Aug 2009
Location: Oak Creek, Wisconsin
Posts: 90
Likes: 0
Received 0 Likes
on
0 Posts
Trim Wanders Up Slowly (power off) O/W Normal! WHY??
Ran into some sandy beach/bottom just barely, leading to minor skeg repair done.
Right after that happened still on water, the port outdrive started to wander UPWARD slowly...without running trim pumps...even under engine power pushing it forward/in.
SSM NXT6 outdrives, NXT1 transmissions, 2007 fountain 700sci's. (the steering is integrated into outdrive setup, I thought this was called ITS)
Boat out of water, Port outdrive starts sloowwly wandering upward against gravity! Trim otherwise acts fine, goes up and down, but when you stop using trim pump, starts its little slow wander up.
I see no fluid leaks and the trim pump reservoir is full.
I grab the outdrive, and it has a slight give, will rock up and down a 16th of an inch or so if that; while the starboard is rock solid, no give up/down.
Why would the trim wander UPWARD against gravity and even under high power, but otherwise act normally?
I will have to remove all power from the trim pump and see if it does it, like maybe the DOWN direction pump is turning a few rpm's even "not trimming" by the switches.
Right after that happened still on water, the port outdrive started to wander UPWARD slowly...without running trim pumps...even under engine power pushing it forward/in.
SSM NXT6 outdrives, NXT1 transmissions, 2007 fountain 700sci's. (the steering is integrated into outdrive setup, I thought this was called ITS)
Boat out of water, Port outdrive starts sloowwly wandering upward against gravity! Trim otherwise acts fine, goes up and down, but when you stop using trim pump, starts its little slow wander up.
I see no fluid leaks and the trim pump reservoir is full.
I grab the outdrive, and it has a slight give, will rock up and down a 16th of an inch or so if that; while the starboard is rock solid, no give up/down.
Why would the trim wander UPWARD against gravity and even under high power, but otherwise act normally?
I will have to remove all power from the trim pump and see if it does it, like maybe the DOWN direction pump is turning a few rpm's even "not trimming" by the switches.
Last edited by xwing; 07-26-2013 at 10:05 PM.
07-26-2013, 11:51 PM
#4
Registered
Thread Starter
Join Date: Aug 2009
Location: Oak Creek, Wisconsin
Posts: 90
Likes: 0
Received 0 Likes
on
0 Posts
Lil Red and Mike Tkach, thanks for answering!
That makes sense, air in line or cylinder would allow such power-off variability in an otherwise incompressible fluid; heating up air could cause expansion and push drive up slowly, or act as a slow spring as it expands/decompresses against trim pump recent action; and could also cause the looseness of the drive when pushing on it by hand.
I had thought we cycled the system enough in driving around and seeing what it was doing to purge any air, but maybe not.
I will cycle the trim all the way up and down a few times to purge air and see if that helps.
That would be the easiest to solve if true! Maybe contacting the lake bottom for a split second put enough force to it that some air got sucked into system, or for some reason sucked air at trim pump reservoir and sent it into system.
Thanks again, will try this in the morning.
That makes sense, air in line or cylinder would allow such power-off variability in an otherwise incompressible fluid; heating up air could cause expansion and push drive up slowly, or act as a slow spring as it expands/decompresses against trim pump recent action; and could also cause the looseness of the drive when pushing on it by hand.
I had thought we cycled the system enough in driving around and seeing what it was doing to purge any air, but maybe not.
I will cycle the trim all the way up and down a few times to purge air and see if that helps.
That would be the easiest to solve if true! Maybe contacting the lake bottom for a split second put enough force to it that some air got sucked into system, or for some reason sucked air at trim pump reservoir and sent it into system.
Thanks again, will try this in the morning.
07-29-2013, 10:10 PM
#6
Registered
Thread Starter
Join Date: Aug 2009
Location: Oak Creek, Wisconsin
Posts: 90
Likes: 0
Received 0 Likes
on
0 Posts
UPDATE: I've cycled the drives up and down about 15 times and port still wanders up a little, and still a little looseness when lifted by hand up and down.
Do people unhook a hydraulic hose or two to "Really Purge" the air out of the system? Seems like might just get more air in that way.
Could there be some stuck or defective "shuttle valve" I read about, or other cause that would not be cleared by standard air purging by running drives fully up and down repeatedly?
Thanks again!
Do people unhook a hydraulic hose or two to "Really Purge" the air out of the system? Seems like might just get more air in that way.
Could there be some stuck or defective "shuttle valve" I read about, or other cause that would not be cleared by standard air purging by running drives fully up and down repeatedly?
Thanks again!
07-30-2013, 12:14 AM
#7
Trim the drive fully in and remove the trim out hose from the cylinder (line connection closest to the transom). Point the open hose into a container and have someone run the trim out until solid oil comes out of the hose, making sure there is enough oil in the reservoir. Reconnect the hose. Trim should be good to go. You could also do this on the other hose after trimming fully out to get all air out of the other side. Your Fountain probably has the pumps on the firewall with long hoses, the bubbles may just move back and forth never getting to the pump.
07-30-2013, 07:38 AM
#8
Registered
Thread Starter
Join Date: Aug 2009
Location: Oak Creek, Wisconsin
Posts: 90
Likes: 0
Received 0 Likes
on
0 Posts
Falcon:
Yes the hoses are long with the pumps on forward firewall. I had been thinking the lines "circulate" and would dump any air in reservoir, but I can see how if the air is at the "perfect" spot it might not ever get back to the pump, or take forever.
I will do what you've outlined above.
THANKS!
Yes the hoses are long with the pumps on forward firewall. I had been thinking the lines "circulate" and would dump any air in reservoir, but I can see how if the air is at the "perfect" spot it might not ever get back to the pump, or take forever.
I will do what you've outlined above.
THANKS!
08-04-2013, 07:22 PM
#9
Registered
Thread Starter
Join Date: Aug 2009
Location: Oak Creek, Wisconsin
Posts: 90
Likes: 0
Received 0 Likes
on
0 Posts
UPDATE:
Tried bleeding the trim pump down by the trim hydraulic cylinder, no change, actually seemed to get worse.
Now, it won't go up against engine drive force in gear at all, and it trims up/out rather slowly, as though fluid is bypassing the trim cylinder or leaking.
There are NO fluid leaks, no decrease in fluid levels.
Switched trim pumps from one side to the other, same thing happens to port...so it is NOT the trim pump.
That leaves the trim hydraulic ram, sounds like a bad o-ring leading to internal trim cylinder leak
I don't have the 2000 psi gauges to test this, but looks like next step is taking off the trim hydraulic ram and taking it apart, I suspect an internal leak, maybe an O-ring went bad or slipped its groove...
Hope it comes off the SSM6 easily...
Tried bleeding the trim pump down by the trim hydraulic cylinder, no change, actually seemed to get worse.
Now, it won't go up against engine drive force in gear at all, and it trims up/out rather slowly, as though fluid is bypassing the trim cylinder or leaking.
There are NO fluid leaks, no decrease in fluid levels.
Switched trim pumps from one side to the other, same thing happens to port...so it is NOT the trim pump.
That leaves the trim hydraulic ram, sounds like a bad o-ring leading to internal trim cylinder leak
I don't have the 2000 psi gauges to test this, but looks like next step is taking off the trim hydraulic ram and taking it apart, I suspect an internal leak, maybe an O-ring went bad or slipped its groove...
Hope it comes off the SSM6 easily...
08-04-2013, 10:07 PM
#10
Are you sure you didn't get the hose (and wire) connections crossed? The two ports on the pump are set a different pressures and if wrong, it will not trim out against thrust. Also, if you over-tightened the hose connection(s) to the cylinder it can crush the brass flare seat and restrict the port. It can be fixed because the seat is replaceable, but it requires some careful work to pull the brass seat out.
