1971 450c milky hydraulic

[campguy]

hi im new to working on dozers, was doing some general maintenance on a 450c yseterday and noticed some pretty milky hydraulic oil in sight glass on tank. any ideas/things to check would be much appreciated. im not too sure if it is air or water being pulled in but any common problems for either of those?

[B Town]

Hello,

I would examine the hydraulic fill cap. It is very similar to a radiator cap, it has a rubber seal and spring. I would make sure they are in good order.

Does your 450C have the external spin on hydraulic filter along side the hydraulic tank or is it the older style with the filter inside the tank. These filter are often overlooked and can restrict follow, causing turbulent flow. There is a pop up on top of the tank that will rise up if the system is restricted.

I would drawn the tank and add new oil. Change the filter. Inspect the cap. Seafoam makes a very good hydraulic oil conditioner, this can help dissipate water. Especially if it is a reasonable amount from condensation.

There are a lot of rub points from the tank to the pump in front of the motor and back to the tank. These can leak and also allow air infiltration, but these are usually visible b/c they leave their mark/leak.

HTH,

Bruce