Hydraulic question for Ford 1920

[TraderMark]

And yes, the power steering is seperate from the 3ph and loader hydraulics. Power steering reservoir is under the hood, on the right side of the engine, just behind the radiator.

 

[TraderMark]

Here's a schematic of the hydraulic piping, filter and pump.

Hope this helps!

Mark

 

[wood butcher]

Mark, your post makes sense. I figured I'd take a closer look and see if there's a screen somewhere. I suspect the machine had the original filter/fluid in it before I did the change. I hope there's a screen that's just full of sludge. That would make this an easy fix. As soon as this snow/ice stops I'll be out there working on the beast.

 

[wood butcher]

And yes, the power steering is seperate from the 3ph and loader hydraulics. Power steering reservoir is under the hood, on the right side of the engine, just behind the radiator.

I thought it was separate. I cant imagine why the oil in it is milky. It's covered by the hood and it has a fill plug in it. The seal on the cylinder is shot so maybe from it sitting out before I bought the tractor water was able to get in around the seal.

 

[TraderMark]

Condensation could have played a big part in the milky appearance of the PS oil. The hot air from the radiator blows on the reservoir and then when it cools, you get some condensation in the reservoir. Check that fluid level and make sure it stays full all the time.


Mark

 

[RickB]

Just because your pump won't self prime doesn't mean it's worn out or worn beyond specs.
In order to self prime, this pump would have to pull the oil about a foot uphill, then suck ALL the air out of the new filter you just installed, then suck ALL the air out of the suction line from the filter to the pump. All the air this pump is sucking has to go somewhere. There's a priority valve between the pump and the next valve in the pressure line. A hydraulic pump can't pump air nearly as efficiently as it pumps oil so it can't push all this air through the priority valve and thus .... gets airlocked. Again, this doesn't necessarily mean your pump is worn out or worn beyond specs.

I agree that trying to rebuild the hydraulic pumps on these tractors is a waste of money, especially when a brand new one is only $300.00


Mark

1920's with sound hydraulic systems self prime just fine, thank you very much. I've been servicing them and other NH tractors since 1997, so I have a pretty good frame of reference. There are only two that I see regularly that don't pick up and prime on their own, and they are both high hour tractors that have had many hot suppers, so to speak. You are correct about priority valves making pumps difficult to prime, but in this case, a 1920 is NOT equipped with any priority valving. This tractor has either a suction circuit flaw or a weak pump, of that I am dead certain. A flow test would prove that, and should be performed prior to a pump replacement.

 

[TraderMark]

Rick,

I'm not trying to say that the tractor shouldn't/couldn't/wouldn't prime itself. All I'm saying is that just because it doesn't prime itself does not always mean the pump is shot and should be replaced.
Yes, a pressure and flow check would be the ideal way to determine pump condition. But those of us who don't have that equipment or don't want to take the tractor in to a repair shop for testing can use other ways to determine whether or not we want to replace parts.

If you look at the schematic I posted from the Ford parts catalog, you'll see that the piping goes from the pump to the "manifold diverter valve" (Item # 1 part no SBA340016640). This may not be a true "priority" valve but it has relief valves and spools inside it much like a priority valve. And those reliefs and spools make it difficult for a pump to push air past them.

Mark

 

[wood butcher]

Rick,

I'm not trying to say that the tractor shouldn't/couldn't/wouldn't prime itself. All I'm saying is that just because it doesn't prime itself does not always mean the pump is shot and should be replaced.
Yes, a pressure and flow check would be the ideal way to determine pump condition. But those of us who don't have that equipment or don't want to take the tractor in to a repair shop for testing can use other ways to determine whether or not we want to replace parts.

If you look at the schematic I posted from the Ford parts catalog, you'll see that the piping goes from the pump to the "manifold diverter valve" (Item # 1 part no SBA340016640). This may not be a true "priority" valve but it has relief valves and spools inside it much like a priority valve. And those reliefs and spools make it difficult for a pump to push air past them.

Mark

Just a side note...when I drained the hydraulic fluid I took 11-14 out. It drained some milky gunk out of it for a while so I just left it out for over a week until I could get back to it. After I refilled the fluid I pulled that plug & spring back out and more fluid ran out of it. I assumed that mean that the diverter valve was full of fluid.

 

[RickB]

Rick,

I'm not trying to say that the tractor shouldn't/couldn't/wouldn't prime itself. All I'm saying is that just because it doesn't prime itself does not always mean the pump is shot and should be replaced.

I didn't condemn the pump. I said it has a weak pump or flaw in the suction circuit. And I still think so. Big difference.

Yes, a pressure and flow check would be the ideal way to determine pump condition. But those of us who don't have that equipment or don't want to take the tractor in to a repair shop for testing can use other ways to determine whether or not we want to replace parts.

One of those methods is coming to places like this to get professional opinions based on years of experience working on dozens if not hundreds of different tractors. If that pump and its plumbing are right, and it has the proper oil and filter in/on it, that pump will prime in less than 25 seconds at 1000 or less ERPM. The OP should not have to jerk around bleeding the pump.

If you look at the schematic I posted from the Ford parts catalog, you'll see that the piping goes from the pump to the "manifold diverter valve" (Item # 1 part no SBA340016640). This may not be a true "priority" valve but it has relief valves and spools inside it much like a priority valve. And those reliefs and spools make it difficult for a pump to push air past them.

Mark

There is nothing in the diverter block that prevents oil or air from passing through with little or no restriction. I'm fairly familiar with that assembly given the thousands of Ford and NH tractors it is bolted to. Not at all like a priority valve, which will often inhibit the priming of an upstream pump.

 

[AlbionWood]

Wathcing this thread with interest as I have a similar, but slightly different, issue with the hydraulics on my 1920. Sometimes when I start the tractor, the hydraulics will not work at all until I rev the engine to full throttle and hold it there for maybe 10 -15 seconds; then I can hear the engine load a bit and the hydraulics are functioning. I'm guessing this indicates an air leak into the suction side causing it to lose prime.