Hi All

I have recently taken possession of an Australian delivered D4 7U (30A).  It is in great condition and has had a fair bit of money spent on it over the years.  My question is with respect to the hydraulics.  Is it normal for the hydraulic ram piston rod to move up to an inch or more depending on load?  For example, I have a heavy after market stick rake and with it raised well above the ground and with the dozer moving forward I can see the piston rod moving an inch or so in/out corresponding to the undulations of the ground.  Also, when using the dozer blade to fine grade this is resulting in significant washboarding, as the bar is raising and lowering depending on how hard the material is.  Everything else seems fine.  It will hold a blade above the ground without any apparent leakage and will push the front of the dozer above the ground when in the fully lowered position.

I am wondering if there is air in the system somewhere,  but I have fully cycled it all several times.  Any help and tips greatly appreciated.

It is normal for the piston rods to move in and out a little bit as the the track frames move up and down independently of each other on uneven ground, it is fluid moving between the rams, you should see one go in and the other out a corresponding amount, they should not move together in the same direction, without you touching the control, that could indicate air in the system.
Washboarding is usually caused by a combination of, lack of experience, soil conditions and how your tractor is equipped.

I would say that the movement would be more likely to be in the joints and pivots rather than in the cylinders themselves. It does take alot of seat time to be able to stop that washboard. As an old friend told the foreman, " Anyone can do that boring flat stuff, it takes real talent to make these perfectly spaced, equal height bumps!" The foreman didnt see the humor the rest of us did.

yes the hydrualics normally float a little. and there is a float function anyway. when in float the blade will follow the ground as the thing is open circuit.
is the pump making any noise if its humming it may be cavitating a bit due to entrapped air. worn vane pumps are noisy.
and yes abit of play is common in the ram eyes we had brass bushes made for ours.

Thanks to all - based on the reply's I tend to think their may be some air in the system as I can definitely see the actual piston rod moving in and out of the cylinder (1-2 inches). I will do some cycling of the system and report back.

Good luck, report back on your findings. We hate being left hanging.

Oil level in the tank should be visible in the filler neck. not topped full.

Do both cylinders more in and out at the same time or does one move in and the other out when the one goes in? What it sounds like is you have oscillating track frames and they're following the ground, With a hard bar in place of the springs (like in a loader) they should move at the same time and direction.

Just a thought