New Holland TC48DA Steering not working after breaking tube.

[ircole]

I broke the tubing that comes out of the high pressure side of the power steering pump (I don't know how but it did break). Of course I lost all steering. After replacing the tubing and filling the power steering reservoir with oil it still won't turn the wheels. The steering wheel just spins. Was wondering if there is some 'bleeding' of the oil that is required to get it to work? It was steering fine before the break. I took the tubing off at the pump and turn the engine over with the starter and it pumps oil (don't have a guage so don't know the pressure). Anyone have any ideas as to what I need to do?
Thanks.

 

[dlctcg]

@ircole - I'm guessing air in the system is your issue...

If the steering system was opened (ie broken tube) & after you repaired it & filled the reservoir, it will most likely need to be bleed. If the pump is working correctly & it is the same procedure as the others in the TC Series (without SuperSteer, then you need to turn the wheels left to right multiple time, with the engine running, until the pumps relief valve begins to operate & bleeds the air from the system. If there is a lot of air in the system (especially in the steering cylinder) it may help to lift the front tires off the ground slightly & you should be able to manually move the wheels left to right. (I believe you could also crack open one of the lines to the steering cylinder & gravity bleed a good portion of the air out.)

Questions: How long did the pump run with the broken tubing? Did it run dry without fluid? if so you may have to make sure it is still working correctly... the only serviceable parts in the pump are the O-rings & seal

Also, I'm guessing you used NH134 hydraulic fluid (or equivalent) to refill the Power Steering system... that's what it requires.

 

[ircole]

Thanks for the reply, really appreciate it. I did use equivalent hydraulic fluid. I didn't run the tractor very long as I couldn't steer it so cut it off right away and then started it a couple of times for a minute or two to lift the front wheels off the ground using the FEL. So hopefully I didn't destroy it.

I was going to try bleeding at the cylinder but would have to unbolt it to be able to disconnect the hoses. After some more thought I'm wondering if it may be the steering wheel not engaging properly with the controller. Back in the winter the fluid was too low and I could spin the steering wheel round and round and it worked properly after adding hydraulic fluid. From some things I've read today it seems that maybe the controller has mechanical stops which would prevent the steering wheel from turning around and around. Do you know if there are mechanical stops?

Tomorrow I'm going to try to get a look at the linkage between the steering wheel and the controller. I think the front wheels weren't centered before I got the tubing replaced and now they are centered which could indicate that the controller is working Ignorance certainly isn't bliss when it comes to this tractor.

The tractor is deep in one of the pastures in dense brush and being not steerable can't get it out. Can't get a truck or trailer to haul it without getting a dozer to clear a path. I never learn!

 

[Harry in Ky]

You don't need to bleed anything. If the pump is moving oil and there is sufficient oil in the tank it will bleed itself. If you replaced the line, filled the tank, and started it up it probably used up the oil pretty quickly. Did you check and fill it back up after trying it?

 

[ircole]

Thanks. Yes, I did add more oil. Maybe the pump isn't working well now. The repair manual states that the tractor can be steered even without the PS pump running.

 

[Harry in Ky]

Yes, that's true. Most hydrostatic units can be steered (with great effort of course) for a short distance with dead engine steering. But that's provided the system was working properly before the pump stops turning. Your situation isn't in that category.

I would expect when you suddenly lost steering you killed the engine, so you shouldn't have really done any damage to the pump. In theory, with the line replaced and oil back in the system the fluid SHOULD have filled everything up by now and you should at least feel some resistance in the steering wheel with then engine off. Yet you say the wheel just spins. And no action at all at the steering cylinder? There's more to this than just a broken/replaced pressure line. .

 

[ircole]

Thanks, think you're correct more than just the replaced line. Maybe I got some contamination in the controller when replacing the line. There's no resistance with the engine running not. Can't move the front wheels at all running or not. With the front wheels off the ground I can't manually turn the wheels left or right other than a little slop. Think there might be some air in the cylinder but wouldn't think that would keep the controller from working. I miss the days of rods and gears.

 

[ircole]

Found the problem yesterday. The spline on the rod going from the steering wheel to controller was barely in the controller and had worn and not engaging any more. Managed to loosen a clamp and get it in deeper and now have steering. So strange that this happened at the same time as breaking the line. Anyway thanks to all for providing me with information and suggestions.

 

[Harry in Ky]

Why is that strange? You removed/replaced the line from the pump to the valve. In the process you had to horse on some fittings to do that. Apparently the support bracket(s) for the valve and/or steering column shifted a bit and you didn't notice. The splined shaft in the controller was evidently just barely making contact before, and the slight movement made the difference. It's as simple as that. It may well have happened sooner or later anyway, but this operation just sped that up a bit.

 

[ircole]

Harry thanks for the response, you are correct the splined shaft was barely in the controller and was badly worn and probably was about to fail anyway. The steering has had some slop in it for a while which in my ignorance assumed was wear in the front end. Now that it is working and I tested steering without the engine running have a theory as to what happened. When the line broke for a number of seconds I was trying to steer it which would be very hard so that stripped the spline and I didn't notice this happening. There is a check valve in the high pressure inlet on the controller which should allow the hard steering even with the broken line. With the shaft deeper in the controller there is no slop in steering now.