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Non-filtered oil supply for hydraulic pump?

December 17, 2014, 09:28:11 pm

I just replaced the hydraulic pump for the cooling fans.  I changed the 3 filters in the tank while it was empty.  I am ready to fill and check for leaks, but have a question.  The pump suction hoses connect to the large outer hole on the bottom of the tank.  The return hoses from the fans connect to the center which then gets filtered as it enters the tank.  The bypass and case drain hoses dump directly into the tank.  According to the scematic in the manual, this is correct.  I am thinking about moving the suction hoses for the pump to the center so that only clean oil is pumped through the system.  Currently any dirt that got in via the dipstick hole would be drawn directly into the pump.  If I can get the fittings loose, anyone see a problem with trying this?  Would the filters restrict flow too much?  Thanks for any insight.

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Re: Non-filtered oil supply for hydraulic pump?

Reply #1 – December 17, 2014, 09:58:25 pm

Dave, I may have an answer for you tomorrow. I'm getting an all-new system now, and I saw three filters in the collection of parts from FOT.

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Re: Non-filtered oil supply for hydraulic pump?

Reply #2 – December 17, 2014, 10:15:43 pm

@Dave I hear what you are saying but I wouldn't worry about it. The hydraulic system does not experience the same harsh conditions the engine does. Some of the hydraulic oil spilling unfiltered back into the system will not hurt. Just my humble opinion.

see ya
ken

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Reply #3 – December 17, 2014, 11:02:53 pm

well as it is pretty much a closed system and hopefully any time you want to check the level you clean the top  cover really well you should not have any reason to change it, just as Ken said.
leave it.
JohnH

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Reply #4 – December 17, 2014, 11:15:36 pm

The filters may not be able to flow all the oil that is required.

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Reply #5 – December 18, 2014, 10:06:37 am

Thanks for the replies.  I know that I am probably over thinking this.

David, if your system is plumbed the same way, it would be interesting to hear the thoughts of the guys at the truck shop.  Good luck on getting out today!

Ken,  your past posts have been very helpful while working on this.  I agree with you and John that it shouldn't be a big deal.

Krush, oil flow is my main concern.

The thought of contaminates circulating though the system with only a chance of being filtered just bothers me.

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Reply #6 – December 18, 2014, 05:24:03 pm

Well, I left the system as is and put some oil in.  @2500rpm, I had about 1400 PSI.  The oil pump made 1100.  The fans a quite a bit louder, but the pressure is still way less than the 2000 it supposedly should be. I looked in the tank and found a solid stream of oil coming from the case drain line.  (see pic if interested)  Can't be good!
 I confirmed that the "2 speed" is working and messed around with the Sun Hydraulics valve and in the process broke it.  New one arrives tomorrow. 

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Reply #7 – December 18, 2014, 06:16:53 pm

Well, as I said on another thread, most of what we got on Wednesday is being sent back, and the right stuff will arrive tomorrow. What I got included three filters (my system has one, in the oil tank).

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Reply #8 – December 18, 2014, 06:55:17 pm

That may be correct amount of flow through the case drain. The drain is there for a reason.

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Reply #9 – December 18, 2014, 07:14:07 pm

@Dave I don't think you should see that much oil coming back from the case drain. IIRC I think it was Alan (alan1958) that said one way to test a motor is to pull the case drain and redirect into a bucket. A healthy flow into the bucket means bad motor. If you have 2 fans you should check each individually using the bucket method.

Alan is a very good resource for hydraulic info. He helped me immensely. You might want to pm him.

see ya
ken

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