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Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 4378
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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HAVE A 2004 BOBCAT 435 EXCAVATOR RESEALED 5 HYDRAULIC

Customer Question

HAVE A 2004 BOBCAT 435 EXCAVATOR RESEALED 5 HYDRAULIC CYLINDERS BOOM BUCKET BLADE ETC DRAINED ALL OF OLD HYD OIL OUT PUT NEW AW 68 COSTAL BRAND OIL & NEW HYD FILTER THE PROBLEM IS AIR IN SYSTEM BLEED CYL THE OIL IN SIGHT GLASS OF TANK IS BUBBLY AND THE MACHINE MAKES A LOUD NOISE LIKE IT IS LOW ON FLUID BUT IT IS FULL I RAN IT FOR 15 MIN AND WORKED THE BUCKET BOOM BLADE TO WORK AIR OUT NO LUCK & I BLEED CLY ALSO ?
Submitted: 11 months ago.
Category: Construction and Road Equipment
Expert:  Dan replied 11 months ago.

Hi Bernie, My name is***** will be glad to help. Most machines today require AW 32 ( 10 W) and AW 46 (15 W). AW 68 is a 20W hydraulic oil and the viscosity is likely too thick for your hydraulic system. Some require 15w 40 actually. Did you find any metal in the filters when you serviced the machine that would indicate a pump problem?

Customer: replied 11 months ago.
NO METEL IN FILTERS AND WHAT IS THE AW ? OF BOBCAT BRAND HYD OIL ? ALSO DO YOU THINK THE HYD OIL COULD BE THE PROBLEM
Customer: replied 11 months ago.
ALSO HOW DO YOU BLEED OUT THE AIR IN THE SYSTEM ?
Expert:  Dan replied 11 months ago.

The AW is the viscosity of the oil.... 32 is 10W, 46 is 15W, 68 is 20w. If the oil is too thick for the system yes it can be your problem. Even larger excavators use AW46 and in older systems or in colder environments AW 32 is used and recommended.

Expert:  Dan replied 11 months ago.

For each cylinder, run the rod 4-6 inches slowly in each direction back and forth and extending 4-6 inches more each time until the end of the stroke is obtained on each cylinder.

Expert:  Dan replied 11 months ago.

How cold is it where you are?

Expert:  Dan replied 11 months ago.

You can run AW 32 or AW46. If you are in a colder climate I would go with the AW 32

Customer: replied 11 months ago.
I am in central FL its warm here all the time LOL Do you know the Viscosity & SPECKS of the Bobcat Factory brand HYD Oil Also when I felt the HYD Filter it was cool not warm after 15 min of running it should be warm ? rite
Expert:  Dan replied 11 months ago.

Click this link.

Bobcat hydraulic oil

Expert:  Dan replied 11 months ago.

Hydraulic systems take time to heat up. It will heat up faster if you put the functions into a stall by deadheding a function at high rpm.

Customer: replied 11 months ago.
okay so how do you get the wrong HYD oil out ? IS THERE A DRAIN PLUG ? & what about oil in cylinders ? And is the oil the problem ?
Expert:  Dan replied 11 months ago.

Hi Bernie. I would drain the tank and try to get as much as you can from the cylinders but would not be too concerned with getting it all. If you are going to AW32 you will be fine with what is left in the system of the 68 and it will mix with the 32. If the pump is still making cavitation noises and there are no other restrictions between the tank and pump suction screen (check it and clean it when the tank is drained), then it is the pump itself that is developed this noise from prior cavitation and wear over time. If this happened only after the repair and service work then hopefully the lower viscosity oil and cleaning the strainer will correct the problem. IF not you have a problem with the pumps themselves

Customer: replied 11 months ago.
Okay do I need to change the case drain filters in the system ? & if so where are they located on the 435
Expert:  Dan replied 11 months ago.

Hi Bernie. The case drain all is tied into the return filter in the tank.

Customer: replied 11 months ago.
Okay do u I need to change them ?? Do you no how many is there ? 1 OR 2 filters ?
Expert:  Dan replied 11 months ago.

Click this link and see page 14 for your filter list.

Filter list

Customer: replied 11 months ago.
they did not list case drain filter on that site
Expert:  Dan replied 11 months ago.

Hi Bernie. There is no case drain filter. The case drain oil is routed through the return filter back to the tank. Case drain oil is return oil back to tank. That is what I meant when I said it is tied into the return filter.

Customer: replied 11 months ago.
O I meant INLINE Hydraulic filter Bobcat part #(###) ###-#### ***** what I have been talking about the also call it a case drain filter they say there is 2 of them on the 435 I don't no where they could be at or if I need to change them DO you ??
Expert:  Dan replied 11 months ago.

Hi Bernie, Using internet explorer click on this link to access the online bobcat parts manual.

http://bobcatpartsonline.com/bobcat/Home.do?isF11=yes

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