Slow opening hatch/trim tabs

[it4llc]

I've got a 2020 C28, which has the common hydraulic pump for the engine hatch and trim tabs. When I've checked on the boat this winter, it seemed that the engine hatch was raising very slowly, but I figured maybe it was due to how cold it was. Today was in the 60s, but the hatch was just as slow to open. Out of curiosity, I checked the trim tabs while at the dock and it took close to a 30 count of holding down the actuator switch to deploy them all the way. (Yes, the engine hatch was closed while I was checking.). They used to fully deploy in about a 12 count. Could low fluid levels cause this? I had checked the fluid and topped it off not too long before the problem started happening and have not noticed any leaking fluid. Any other suggestions for trouble-shooting?

 

[baz]

Have you detected any change in the pump's noise when opening the cockpit hatch compared to when the hatch opened quickly?

 

[it4llc]

Hard to say - maybe a little bit deeper tone than before, but not a dramatic change. Could there be any blockage in the pump/line somewhere?

 

[BB marine]

I would suggest checking fluid level. The C28 has small beckson plates located under the aft seat remove Both plates and place a flash light through one and look through the other. The trim pump is located starboard side aft just above the grid stringer mounted to the transom. You must have the trim rams retracted and hatch closed when checking the level. The trim fluid should be at the high line on the pump reservoir. I use ATF the same fluid you use in the reverse gear.

If the level is low it will cause the trim tabs and engine hatch to operate slower. The reason is the pump will have cavitation. When raising the engine hatch you should always make sure the trim tabs are fully retracted. The Reservoir does not hold enough fluid to fully extend the trim tabs and lift the engine hatch at the same time.

 

[it4llc]

Thanks Brian for the detailed explanation, in particular the reason for slower operation due to low fluid levels. I will check the fluid level again and report back...

 

[CaptT]

You may also want to check your batteries. When my batteries dropped below 12 volts the hatch moved very slowly. With a fully charged battery the pump ran much faster.
Just something I observed with my C28.
Terry

 

[Scuba Too]

I had the same issue on my R29 CB and it was due to the fluid level being low. Added more yesterday and it's back to normal operation. Before adding fluid make sure that the trim tabs are all the way up and the hatch closed - this is when the reservoir will be at it's fullest. If fluid is added under other states it could overflow. Once filled run the hatch up and down a few times to purge out air bubbles.

 

[dbsea]

following... what kind of fluid does one put in there? is there dedicated hydraulic fluid? I saw someone else post that you can use ATF? is that what is in there now?

 

[it4llc]

I believe any ATF fluid can be used, and they can be mixed, according to the Bennet manual: https://bennetttrimtabs.com/wp-content/uploads/2015/02/owners_manual.pdf