SAE j1171 trim motor. Pressurized air in reservoir. Leg falling slowly

[NorinRadd]

290 leg. Trims up and down great. Slowly falls when trimmed up. No leaks in hoses. If I trim up and open the fill hole theres a tiny bit of pressurized air. If I go down there is more. Still quite minimal but its there. Ive cycled up and down 6 times. It seems like its gotten less but its still there. Leg still falls but maybe slower. Hard to say. I dont want to keep doing it if im hurting something.

Could it take 10 cycles and burps to clear the air?

 

[alldodge]

Moved to VP because trim issue with 290 leg

I don't see an issue with the air, it appears to me that there is a internal leak in the pump or the trim cylinders

 

[NorinRadd]

Moved to VP because trim issue with 290 leg

I don't see an issue with the air, it appears to me that there is a internal leak in the pump or the trim cylinders

There shouldnt be air in the lines and there is no leak. Fluid level has stayed the same.

 

[alldodge]

There shouldnt be air in the lines and there is no leak. Fluid level has stayed the same.

Agree, didn't see anything about air in the lines only the fill hole

Running the led up/down increases some heat and heat expands.

 

[NorinRadd]

Agree, didn't see anything about air in the lines only the fill hole

Running the led up/down increases some heat and heat expands.

But I have read everywhere to bleed air in system cycle leg up and down. Burping reservoir at every interval.

 

[alldodge]

Paging @kenny nunez

 

[ESGWheel]

But I have read everywhere to bleed air in system cycle leg up and down. Burping reservoir at every interval.

AD's point is that for the reservoir, accessed by the filler cap, its ok to have air. In fact, it needs it. Your lines should not have any air which is purged by the cycling you are doing. Think of it this way: when you check your brake fluid on your car the reservoir is not completely full. But there is no air in the lines either. I did a mockup and compared it to your pic to help.

And you are correct, no air in lines as its compressible and will allow for movement (or a squishy break pedal). But if its purged via the cycling and not leaking anywhere then it’s an internal leak.

 

[NorinRadd]

AD's point is that for the reservoir, accessed by the filler cap, its ok to have air. In fact, it needs it. Your lines should not have any air which is purged by the cycling you are doing. Think of it this way: when you check your brake fluid on your car the reservoir is not completely full. But there is no air in the lines either. I did a mockup and compared it to your pic to help.

And you are correct, no air in lines as its compressible and will allow for movement (or a squishy break pedal). But if its purged via the cycling and not leaking anywhere then it’s an internal leak.

Ohh ok! So should I just cycle up and down without opening the cap and burping the pressurized air?!

 

[ESGWheel]

While I do not have the manual for this device, yes, that would be ok with a qualifier. The qualifier is IF there was lots of air in the lines, the ‘burping’ is needed as well as the need to fill it back up to the proper level during the cycling process > you do not want the level to drop below the intake for the pump (which you cannot see because its inside the reservoir). But given you have already cycled it a bunch of times a few more will not hurt and then check the level. If you get a little pressure coming out, that is OK too. AD’s comment about heating up is that the cycling heats up the fluid (which causes it to expand some) and creates a little pressure in this sealed system.

IF you find during that process you need to add a lot more hyd fluid, then keep cycling and filling it back up (burping). But if there really is not any more to add or even a little of the fluid comes out (due to expansion) you are ok and the system is purged of the air.

Now onto your original problem of “Slowly falls when trimmed up”. If it continues to do so and NO external leaks, there is only one answer > internal leak in the pump or cylinders.

 

[NorinRadd]

While I do not have the manual for this device, yes, that would be ok with a qualifier. The qualifier is IF there was lots of air in the lines, the ‘burping’ is needed as well as the need to fill it back up to the proper level during the cycling process > you do not want the level to drop below the intake for the pump (which you cannot see because its inside the reservoir). But given you have already cycled it a bunch of times a few more will not hurt and then check the level. If you get a little pressure coming out, that is OK too. AD’s comment about heating up is that the cycling heats up the fluid (which causes it to expand some) and creates a little pressure in this sealed system.

IF you find during that process you need to add a lot more hyd fluid, then keep cycling and filling it back up (burping). But if there really is not any more to add or even a little of the fluid comes out (due to expansion) you are ok and the system is purged of the air.

Now onto your original problem of “Slowly falls when trimmed up”. If it continues to do so and NO external leaks, there is only one answer > internal leak in the pump or cylinders.

My thought is maybe I need to cycle and not open the check valve to burp the pressurized air? Would it self regulate?

 

[ESGWheel]

When the system is normally operating there is no need to open the fill valve. You go all day and many more without ever needing to open it. If you have cycled this 10 or more times post whatever maintenance you have done on it, and the fluid level is not dropping anymore, then you can cycle it a 100 times with no need to open it.

Which brings up a question not yet asked: why were you trying to burp it in the first place? Was it due to the falling leg? If yes, and you started this burping process becuse of that, did you have to add a lot of fluid the first time to get it to the full level? This is a sealed system and does not loose fluid except by leaking externally.

 

[NorinRadd]

When the system is normally operating there is no need to open the fill valve. You go all day and many more without ever needing to open it. If you have cycled this 10 or more times post whatever maintenance you have done on it, and the fluid level is not dropping anymore, then you can cycle it a 100 times with no need to open it.

Which brings up a question not yet asked: why were you trying to burp it in the first place? Was it due to the falling leg? If yes, and you started this burping process becuse of that, did you have to add a lot of fluid the first time to get it to the full level? This is a sealed system and does not loose fluid except by leaking externally.

When the leg is all the way up. It slowly drops down. Maybe takes 30-40 minutes. My mechanic just said to burp airbubbles in the system if trim is dropping. So thats what I tried. It hasnt leaked any fluid. The fluid level has remained the same the entire time, at appropriate levels as far as im concerned. When leg is all the way down the fluid is just at the fill hole. There is pressurized air when I trim it up or down and open the res fill plug. I figured I needed to open the plug to let the air out.

 

[ESGWheel]

You have an internal leak.

 

[QBhoy]

Hi. This is extremely common an issue with this particular model. It’s almost exclusively caused by the small check valve balls passing and not holding as they should. Your situation of it dropping down but not externally leaking or losing oil…is the tell tale sign of it.

 

[NorinRadd]

Hi. This is extremely common an issue with this particular model. It’s almost exclusively caused by the small check valve balls passing and not holding as they should. Your situation of it dropping down but not externally leaking or losing oil…is the tell tale sign of it.

Intersting. So what needs to be done?

 

[alldodge]

In most cases it's the cylinders that need new seals. Rebuild kits can be found and easy enough to do