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1490 Power Steering Pump Under Pressure - Leaking

Posted: Sun Jul 04, 2010 3:20 am
by pringles
Hi all,

I had the 1490 out in the field for it's first trial run finally after 2 years of repairing it.

One of the things I did to it was to remove the power steering pump, drain it and take it apart and replace the filter and o-ring. I cleaned all the insides of it (it was pretty clean) and checked the over pressure valve to make sure it was clean and working.

As the manual says, I re-filled it to the top of the fill hole and away I went. I noticed that after a while it was leaking quite a bit around the large o-ring that seals the pump head and the thin metal body or can. I removed the fill hole bolt and fluid came pouring out seemingly under pressure and way to full. I was shocked since I filled it only to the top of the hole like the manual says. I put the bolt back in and kept going. Fluid continued to leak out but maybe not as much. Now the fluid is quite a bit below the fill bolt hole. When I pull up on the vent it makes a slight hiss like it's a bit under pressure but nothing crazy. It does not leak just sitting there or when running a bit from the barn up to the house when it's cool. It only seems to leak when under load working for a while and warm. Maybe it has gotten to a level that it is happy with and will stop leaking but I had to stop the tractor because I was doing something else so I am not sure if it will just keep on leaking until it is empty. It did not seem to do this before I changed the fluid but I also put a new fill bolt nylon washer on and before the old one was not sealing. The old fluid before I changed it was quite a bit low as well. The vent seems to work so I don't know how the new washer would have anything to do with it.

Does anyone have any brilliant ideas as to what could be causing this. It's so annoying I just feel like going out and buying a new pump and to hell with it.

Thanks,
Steve.

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Sun Jul 04, 2010 10:12 am
by Alchad
Steve,

If you've replaced the large o ring between the can and the pump body it seems strange that you've got a leak, unless the can itself is under pressure, which means that the pressure valve is either letting by because of overpressure - a restriction downstream. Or you've done something wrong in reassembling the pressure valve.

You don't mention any problems with the power steering itself, so that suggests it's not a downstream restriction causing overpressure, which leaves the valve letting by as the problem. I think the manual says the pressure valve should not be taken apart, although I have in the past to no apparent ill effect.

I'd take the pump off again and check everything over again, particulary the pressure valve, before buying a new pump.

Good luck

Alchad

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Sun Jul 04, 2010 1:29 pm
by pringles
Thanks Alchad. I will have to have another look. I didn't actually take the over pressure valve apart, I just made sure that it was functional and clean.

I have read on here that some machines seem to have a pipe from the pressure valve running up to the top of the engine. I don't have this. My pressure valve is just a little button on top of the pump that lifts under pressure and has a spring that sets the pressure release. Do you know what the purpose of the pipe etc is from the pressure valve to the top of the engine. I am thinking that I might be missing something. My machine is a 1980, so maybe something changed later on.

Thanks again,
Steve.

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Sun Jul 04, 2010 3:24 pm
by Alchad
Steve,

Hi,

Just to make sure we're talking about the same thing - see diagram below, the pressure (relief) valve I was talking about is item no 9, you seem to be talking about the vent line - item no 34?

Regards

Alchad

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Sun Jul 04, 2010 4:30 pm
by roundhill
If the pipe(34)is crimped or blocked then you will get pressure from the oil warming up. the pipe can be replaced with flexible tubing. would fit tubing of larger diameter than you currently have. 8mm internal. This will give enough room for the oil to move when going from lock to lock.

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Mon Jul 05, 2010 3:42 am
by pringles
I was confused between the vent and the pressure relief valve. I was talking about the vent.

I don't have a vent like that. My pump just has a little button where the picture above shows a pipe connecting. My vent is just a button that is held closed with a spring. Was there a change in the design of the vent on later 1490 tractors? If I don't have this to allow the oil to move in the pipe, could this be my problem? My pump does not have any fitting that a pipe could connect to, just the little vent as I described above. It does not look like it has ever been modified.

Thanks,
Steve.

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Mon Jul 05, 2010 7:40 am
by roundhill
Perhaps if you post a photograph of the vent. Someone may be able to help further.

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Mon Jul 05, 2010 9:36 am
by Alchad
Steve,

It is just a breather vent, just two different types of design.Normally there shouldn't be any oil getting into the pipe, or coming out of the vent.

AS I said in my earlier post, it does sound as though you're getting pressure back into the suction side of the pump. Did you notice any problems with the steering when you were driving the tractor?

Alchad

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Mon Jul 05, 2010 5:04 pm
by pringles
Before I can tell if the pressure relief valve is bad I am replacing the o-ring on the hydraulic coupler at the top. I think it's the outlet but I forget. It might be leaking there and dripping down the back of the pump where I can't see. If it was the pressure relief valve causing pressure in the canister you would think that it would blow out the vent on the top.

The reason I am wondering so much about the two types of pumps (different vent types) is that I might have to replace the pump. There is no problem with the steering at all but the pump makes a bit of a funny noise when it's running. I stopped at the Case dealer this morning for some other stuff and I asked them about what type of pump they have. They only have the type with the vent pipe fitting, not the type that I have. This will mean that I will have to modify my tractor with parts from a bone yard because the vent pipe connects to the parts shown in the above diagram. This is unfornunate. Has anyone been able to buy the pump with the button type vent instead of the pipe fitting type. They sure look different when you look at the pictures of them.

In my manual it shows photos of them taking the pump off and it's the type I have with the button vent, but on the next page it shows the picture that is shown above. I am not sure when they made this change but it's strange that both types are shown in the same repair section of the manual.

Steve.

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Mon Jul 05, 2010 6:36 pm
by Alchad
Steve,

I'm as certain as I can be that there's only one type of pump fitted, it's just the vent/breather arrangement that's different. If I had to fit a new pump and I didn't have the correct connection, I'd probably just use a piece of plastic tubing bent over at the top!

For info, pictures below show the original pump (the one on the grass) from my 1390 which had a button vent and a breather connected to the fill point, the other two show the replacement pump with the normal breather, and where the breather pipe connects to into the rocker box cover - which again is a design variation to the parts diagram above.

Regards

Alachad

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Mon Jul 05, 2010 7:05 pm
by pringles
Now I am really confused. Mine has the button vent like your first picture but the fill bolt or plug does not have a hole tapped in it for an additional breather like your picture shows, it's just a bolt like your middle picture. When the breather/vent is from the fill bolt or when it's from the button vent point as a tube, does it get routed to the rocker cover in both cases. This seems very odd to me. You would think crap from the engine could get down the pipe into the pump.

I am very curious to get home and have a look at my rocker cover to see what's there. I had no idea this was done like this.

Thanks a lot for the pictures, they are very helpful.

Steve.

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Tue Jul 06, 2010 5:11 am
by jazo
if you were to replace the pump i would just put your canister on the new pump

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Tue Jul 06, 2010 2:49 pm
by pringles
I was actually thinking about that as well.

I checked last night and my rocker cover has only one pipe coming from it that is connected to a rubber pipe that is directed down through a hole in the frame for any engine blow by. There is no pipe for the line that goes to the power steering pump vent. I guess my tractor never had this at all. I was wondering if it was changed or messed with my a previous owner.

Thanks for all the help everyone,

Steve.

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Tue Jul 06, 2010 3:18 pm
by Guest
I think the differences between the vents on the pump reservoir housings are that the tractors prior to the 90 series had the 'button' vent and when this type operated oil would run down over the housing and all the dust and other stuff floating about in the air would stick to and mix with it making a mess so this was modified with the pipe type vent that vented up into the rocker cover thus eliminating the mess, basically just a change in design, not anything more. The button type vent rarely gave any problems and never actually vented unless the filter element collapsed creating pressure within the reservoir or if over filled with oil. There is no reason not to replace the pipe vent reservoir with one that has the button type. Some did have a sort of vent incorporated in the top of the filler plug and all this did was to allow oil to 'vent' if the reservoir was over filled. Pressure issues would suggest that it is the seals that are giving the problem or the filter element being blocked or collapsed. The pressure valve could possibly be at fault but this is very rare as the valve is set and sealed in the factory. You should never attempt to ajust the pressure valve as, like I say, it is factory set, if the valve is suspect then a new complete valve unit should be fitted.

RE: 1490 Power Steering Pump Under Pressure - Leaking

Posted: Wed Jul 07, 2010 1:20 am
by pringles
Thanks for the explanation Powerrabbit, and to everyone else as well. I haven't been able to play with this lately because my battery is at the dealer for a warranty claim (and of course they are trying to get out of replacing it). I've been trying to get the trail widened to my two back fields as well since the 1490 is rather large compared to my other tractor. Once I get my battery and get the trail widened I will be able to test if the new hydraulic coupler that I bought is the actual cause of the leak. It's kind of difficult the last few days to clear the trail because of the 34C weather and the ten thousand deer fly's swarming around my head. It's easier to sit inside in the AC and wait until the weather cools off a bit.

thanks again,
Steve.