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Author Topic: 420AN Power Steering Issues  (Read 90 times)

k350024v

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420AN Power Steering Issues
« Reply #1 on: May 07, 2020, 05:30:31 PM »
I've recently acquired a 420AN, older model probably mid-early 80's.  When I first bought it it would'nt steer at all, you had to lower the bucket to get the front wheels off the ground and steer it.  The previous owner installed a completed front end from a parts tractor.  From what I Can gather before that it had some cobbled power steering setup.  Anyway i rebuilt the steering booster and adjusted the pressure relief valve as far as I could (I think its a pressure relief valve, its a spring loaded plunger on the top of the booster)  When cold it works but you can still hear the pump whine when your turning like its blowing past the pressure relief valve.  When I first rebuilt it after a little while of running it wouldnt steer again.  I drained the hyd fluid and put in 15w40 engine oil which helped alot.  But still when its hot it will barley turn, and most of the times with a load in the bucket it wont.  I think the pump is fine as the loader and 3 point works fine.  Not sure if anyone has had any experience with these.  I'm not a stranger when it comes to hyrdaulics but this one has me kind of stumped.  Is 15w40 the correct fluid to run?  Almost seems to me like when the fluid gets warm its causing an issue.  Should I run something thicker?  Looking for any ideas before I buy a new booster.  I did try putting a spacer to add spring pressure to the "relief valve" but it just started pissing oil from one of the fittings.


Thanks
Mike
  • Belarus 420A, Fordson Super Major Backhoe, Oliver OC6 Crawler, other misc junk