A long while back I replaced the reader assembly on my hydraulic tank as it was 30 years old and in desperate need of repair. I put on an aftermarket one as the NH one was ridiculously priced. I haven’t noticed it until the last few times, but after the machine gets hot if I take the breather off of the hydraulic tank, I noticed that the tank is pressurized. Does anybody else notice this on their machine? Maybe I do not have a high enough breather as I couldn’t tell what the NH one was.
Stupid autocorrect and I can’t edit my original post…. I replaced the BREATHER assembly.
I intentionally bought a 3 PSI cap for mine and it holds pressure. It's supposed to vent anything over 3 PSI so shouldn't cause any problems.
Ok I wasn’t sure if it was supposed to be pressurized or not. Thanks for the reply.
Mine was not venting as well so I simple took the O ring off the breather cap, opened up a couple small grooves under its channel and be sure not to over tighten it. No more vac or pressure issues.
Before replacing mine I took the original apart to clean it a couple of times. It had a seal and spring that indicated a pressure release and that is why I ordered the generic with a pressure release. It's been in place for 3-1/2 years and so far has not seemed to cause any problems. I think maintaining some pressure might prevent condensation from forming but not sure. I used to have a problem getting water in the oil and that ceased around that time but I also moved the machine into a barn out of the rain at the same time. With it holding pressure I at least know I don't have any holes in the tool box or tank. This is my original thread on the cap I used. HeavyEquipmentForums
If the tank has a breather it is going to take in a lot of water vapor due to the expansion and contraction of the oil as it goes through temperature changes. It is amazing how much liquid water is created in the tank as a result. The same is true for fuel storage tanks. A small amount of pressure in a hydraulic tank is a good thing. IMHO.
A lot of hyd. systems are designed to have 3 PSI or so reservoir pressure. They have vented caps so they don't over pressurize.
My 675E has a slight pressure after running...all good.
Appreciate all the responses. Thanks.