Volvo Penta SX-M Trim drifting down.

sledman11

Cadet
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Oct 27, 2014
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29
My trim is drifting down slowly. Probably drift down halfway over about 3 hours. Can't see any leaks any where. Fluid level is fine. Is there a check valve that if faulty would cause this and if so, is it located in the trim cylinders or in the pump? Appreciate and suggestion as to what could cause this.

Thanks,
Don
 

Bondo

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Apr 17, 2002
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Ayuh,..... There are valves in the trim pump, or the cylinders could be by-passing internally,.....

Is the trim pump full of oil,..?? is it clean,..??
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Most likely cylinder piston seals leaking
 

sledman11

Cadet
Joined
Oct 27, 2014
Messages
29
Ayuh,..... There are valves in the trim pump, or the cylinders could be by-passing internally,.....

Is the trim pump full of oil,..?? is it clean,..??
Thanks for the response. The trim fluid was clean but the level was way down when I first looked at it. So the fluid can bypass internally and there are no external evidence of a leak? Is there any way to figure out if the issue is with the trim cylinders or the pump? I did find some fluid sitting on top of the fluid reservoir this morning. Maybe leaking from between pump/motor and the trim fluid reservoir?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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I am not seeing a leak by the trim shafts
I said piston seals (internal) not gland seals (external)

the blind end is bypassing the cylinder to the rod end. this could be the piston to rod seal, or this could be the piston to barrel seal.

plastic/rubber cylinder seals last about 20 years and then they need replacing.
 

Lpgc

Petty Officer 2nd Class
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Jun 17, 2023
Messages
179
@Bondo and @Scott Danforth recently helped answer my questions about my Volvo drive dropping. I may have been lucky because I found a weep where a line connects to the pump, fixed the leak (new Oring), filled with new fluid, bled the system and so far it hasn't fallen again. I haven't tried it on the water yet so there is still a chance my pump or rams have an interal problem but it's not falling under it's own weight while the boat is on the trailer now. I had my engine out for a rebuild so was able to check for leaks where the hydraulic lines connect through the transom fittings, was pleased not to find any other leaks.
 
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