Oliver 770 Power Steering problems

Hi guys,

My Oliver 770 power steering has never worked like it should (always was stiff and hard unless running at over 1500 RPM)...but on Friday it just plain quit...Impossibly hard to steer, I basically could do nothing except get it parked.

My dad said he thinks the previous owners he got it from ran it low on PS fluid and probably damaged the pump. So my assumption is that it needs a new pump or the pump needs rebuilt, but I know there are many here who know a ton more than me so I thought I would ask what the best steps are to take.

After it started steering really hard I check the PS fluid which was near add but was not in the low yet. I added more fluid and turned the wheel all the way both ways to see if that would help...beyond that I have done no diagnostics....

As always, thanks in advance for any advice and input. Attached are some pics of the Power steering pump.
Questions are...
1. are there other diagnostics I should do to determine the problem or should I just assume its the pump.
2. can the pump be rebuilt? If so where can I get parts?
3. If the pump can't be rebuilt then where could I get a new one? My initial searches turned up nothing for power steering pumps on most of the websites I use to get parts.
4. What are tips/tricks for tearing apart and re-assembling these? I know its important to not have air in the line? How do I bleed the line and test the pressure to make sure things are working properly?
Shot of the 770 wiht the side tin off
mvphoto19178.jpg

Various shots of the Power steering pump.
mvphoto19173.jpg

mvphoto19174.jpg

mvphoto19176.jpg

mvphoto19177.jpg
 
First of real quick like, going to combine here. Check the pump first, also remember a leaking relief valve in the pump will act just like a worn out pump. You are going to need a 2000 PSI gauge some fittings and a shut off valve plus some other small stuff. Got a phone number? J.
 

Ok, so I am assuming what I am going to need to do is basically construct a pressure testing gauge to place in the line correct?

I see a 0-5000psi Hydraulic pressure testing gauge at Fleet farm...assuming that's what I'd need. Next question is how do I splice that into the line and then where in the line to I put it?

Assuming the valve goes on the back side of it so I can turn the wheel to make the pump push and then watch to see what the pressure gauge does when the valve is closed?
 
Ok got the valve setup done with a pressure (3000 psi max) gauge.

Started the tractor and closed the valve...the needle didn't even move, it pushes the ps fluid through when the valve is open but very slowly.

So what next? Does that mean the pump is shot? If so where do I look to get a new pump?
 
Anyone have further advice on this? Where to find parts or a replacement pump etc?

J. Schwiebert I misplaced my notes and your number so I couldn't call you back....

Any insight would be appreciated. Not that it's needed but here is a shot of the gauge, with the valve closed...reading 0 :cry:

mvphoto19364.jpg
 

John, I haven't had a chance to get the valves swapped out between my 550 PS pump and my 770 to see if the relief valve is the problem or if its the pump. Hoping to get to that this weekend if I have time. My problem is I need the 550 running right now and I need the 770 too...Too many things to do and too little time.

I am actually thinking I may just want to replace the pump and then have the old pump as a spare parts unit if anything in it is still good since the 550 and 770 have the same pump. I will likely have more time this winter when there isn't mowing and fencing to do and could troubleshoot it better.

Anyway bottom line is I would like to find a new or rebuilt pump that I know is going to work. Can you or anyone else point me in the right direction to get a replacement pump?

Thanks,
Patrick
 
Well guys thanks to John S. and others here I was able to get the pump tested properly and it was shot. I sent it in to Maibach tractor for a rebuild (actually they sent me a different rebuilt pump but same difference basically.

Anyway new pump is pushing 900psi right where it should be at idle, but the problem now is all that great pressure revealed a new problem. :(

Previous owner of the tractor must have broken the steering gear somehow, so it had been welded all around where the snap ring goes in.

All that nice pressure cracked several of the welds so I find myself in need of the body for the power steering gear and the o rings as well. Also we broke a bolt getting the steering gear out so I need that as well.

Anyone have any good sources for getting the housing, bolt and the o-rings so I can get this tractor off the DL? Being that its one of two I have I am sorely missing the poor thing at the moment. :)


mvphoto21098.jpg


mvphoto21099.jpg


mvphoto21100.jpg


So from the picture above I need the O-rings which are #s 5, 6, 12, 16, 17 and 22.
I also need the housing: #14
and I need the tapered bolt that goes through the hole by #14.

Of course in my haste to get home I missed taking pictures of the next page which shows the rest of the part numbers. I'll try to get that tomorrow morning before I head to work.

Anyone who has any idea where I might be able to get the housing if you could let me know that would be greatly appreciated.

Thanks!
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top