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CAT 301.8 stick comes slowly in on its own

Kenskip1

Well-Known Member
Joined
Feb 13, 2019
Messages
129
Location
Missouri
How about reversing the hydraulic lines? This could tell you something. If the stick extends then this sounds to me like a leaking valve.
 
Last edited:

BigWrench55

Senior Member
Joined
Oct 11, 2018
Messages
1,176
Location
Somewhere
If it is anything other than bad piston seals then oil will return to the tank. Do the test again and watch your sight glass on the hydraulic tank. If the level doesn't rise then the cylinder seals are the problem. Also you can hold the cylinder in question into relief with a helper and check the temperature at both ends of the cylinder. If one side is significantly hotter than the other. Then the seals are blown. But you would hear the oil bypassing long before you could can hold it in relief long enough to get hot. My vote is cylinder packing.
 

pete40

Well-Known Member
Joined
Aug 2, 2008
Messages
61
Location
Australia
Ok fellas thanks for the input. Turns out a neighbour of mine is very handy. He lent me some plugs and I have now isolated the valves in question and the stick still comes in, thus it is the seals in the cylinder. They have just now been ordered from CAT and I will set about dismantling and replacing. If I run into trouble, my neighbour will be able to point me in the right direction.

Thanks everyone. I'll post up when it's fixed. Hopefully that might be tomorrow afternoon, Australia time.
 

jbernielh

Well-Known Member
Joined
Nov 25, 2016
Messages
72
Location
victoria bc
if the main seal on the piston is a flat ring type seal check back for installation tricks..
had to deal with that on the 305

Bernie
 

pete40

Well-Known Member
Joined
Aug 2, 2008
Messages
61
Location
Australia
Ok, found the problem.
IMG20210617155738.jpg
All the seals have now been done. I'll put it back on tomorrow. Should work a fair bit better now.

New seal kit from CAT had a blue seal where that orange one has failed. I'm thinking that one was not genuine.
 

uffex

Senior Member
Joined
Jan 23, 2012
Messages
4,464
Location
Lincoln UK
Occupation
Admin
Good day
May be prudent to ask why the seal failed.
Kind regards
Uffex
 
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