How to choose backstay oil? how to clean circuit?

[AleCiotti]

Hi, guys I have a Navtec a250 -22 backstay, it started leaking oil from the top, I suppose the seals have worn out over the years.

I will be rebuilding the cylinder and I also wanted to change the oil, but I can't find what type of oil I should use, do you guys know anything about choosing the correct one?

I also have a Navtec Vang connected to the same circuit of the Backstay, do you guys have any recommendations/resources on how to clean the circuit before refilling with new oil?

Thanks!

 

[Bilgediver]

You may have power steering oil on board. Usually it is a mineral oil and a wide selection is available on Amazon .

 

[AleCiotti]

Update, I've read everything I could find in other forums and resources online, The air-pressured side of the cylinder which helps it extend when releasing pressure is full of oil, so from my understanding there has been a seal failure due to not having been changed in many years and wrong oil. (other than the seal failure on top of the cylinder that caused the oil to leak out)

What I will have to do from what I've read is:
1. Remove the cylinder for a rebuild (change seals with new navtec ones)
2. Detach the endpoint of the oil supply to the cylinder (at the cylinder) and pump new oil through the system to push the old one out with any contaminants that may be present in it.
3. Put the re-built cylinder back in place, add 100PSI of air pressure through the schrader valve at the base of the cylinder using a common bike pump.
4. Test the system

My questions are:
- when I detach the endpoint of the oil supply to the cylinder I will create an air ingress? is that a problem? is there a way to burp the air out of the system after reconnecting the oil supply to the cylinder?
-should I run mineral spirits through the system lines to clean them before pumping the oil in?

Thanks in advance.

P.S. i found the correct oil

 

[HenrikH]

With regards to the piston seal, mine is seeping. Once a year I open the valve a empty the back side. Then I add that to the overflow into the support container and I am good for another year

 

[AleCiotti]

Yeah, but I'm looking for a definitive fix, bleeding the air container from the oil that surpassed the seal, and adding more oil to compensate every year / when the piston blocks is a short-term fix and will likely cause more problems down the line, wouldn't it?
Thanks

 

[Zing]

Yeah, but I'm looking for a definitive fix, bleeding the air container from the oil that surpassed the seal, and adding more oil to compensate every year / when the piston blocks is a short-term fix and will likely cause more problems down the line, wouldn't it?
Thanks

The bloody things leak as soon as you look at them. I’ve spent a lot of time rebuilding my cylinders and the pump/diverter valve system. 3 cylinders and a pump with 5 full rebuilds in 13 years. Oil sprayed in my face from burst hoses. Puddles and mess from leaking fittings all over the shop from hoses and seals. Dripping oil on my forehead at 2:00 am in bed from a leaking pump. It’s life with hydraulics, get used to it.

Actually no, there is a better way. Change all cylinder and pump and valve seals, o-rings and hoses early as a preventative maintenance measure. I reckon roughly 6 years is a good time. That way you have a lot of work, but few emergencies and few if any high stress situation leaks.

You can easily and fairly cheaply pump through new oil to flush the system of old oil, dirt and air. I do that whenever I do a rebuild. I don’t know if it actually does any good, but it surely can only help.