1490 Hydraulic issue

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dtw
Posts: 39
Joined: Tue Nov 23, 2010 11:08 pm
Location: newfoundland canada

1490 Hydraulic issue

Post by dtw » Fri Sep 08, 2017 4:18 pm

Good day to all

I have a 1490 case IH and there was a new hyd pump replaced on it three years ago.
I was noticing some sluggish movements in the back digger , so I put a pressure gauge on the remote valve running the digger.

With the engine rpm's at 2000 , the pressure guage went to 1700,psi and within 30 seconds it dropped to around 1200-1250psi and remained there.
I then tested the second remote valve and found the identical readings.

Question?
Is there a Pressure relief valve or a by pass valve in the hydraulic system which is not functioning correctly.
Could the bypass or relief valve be lifting 'till it hits 1200 psi and then seal???

I would appreciate any help out there.
Thanks very much
DTW

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DB780
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Location: Lincolnshire

Re: 1490 Hydraulic issue

Post by DB780 » Sat Sep 09, 2017 9:23 am

If you are running the digger from a remote it is by-passing the internal hydraulic system. Have you check the suction filter or changed the pressure filter one or both may be blocked. If these are good then it is either the pump or relief valve. The relief valve located along the pressure line from the pump and under the gearbox, you need to drain the oil to inspect this.

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dtw
Posts: 39
Joined: Tue Nov 23, 2010 11:08 pm
Location: newfoundland canada

Re: 1490 Hydraulic issue

Post by dtw » Sat Sep 09, 2017 11:24 am

Thanks for the info.
If I am going to check the relief valve , (a square block in line on the hydraulic line ??) I may as well check both the filters, drain the oil , ect.ect.

I'll probably get at it today and see what is up with it.
Thanks.
DTW

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ollek
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Location: South West Finland

Re: 1490 Hydraulic issue

Post by ollek » Sat Sep 09, 2017 12:01 pm

The pump is sucking the oil trough a washable strainer, situated under the gear box. The pressure filter behind the rear axle has to be changed. The pressure relief valve is ref number 14 in the following drawing from the parts catalogue. https://partstore.caseih.com/us/parts-s ... 9ar1303578 damaged O-rings with ref numbers 2, 11, 15 (2 off) and 19 can also give low pressure.

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dtw
Posts: 39
Joined: Tue Nov 23, 2010 11:08 pm
Location: newfoundland canada

Re: 1490 Hydraulic issue

Post by dtw » Sun Sep 10, 2017 8:54 pm

Hi all,
just an up date on the hydraulic problem???

Oil drained , and it looks good and does not have any odd smell, ( hydraulic oil when it has been extended beyond it 's life cycle can have an off smell , burnt , or not as new oil should smell.) I am comparing the oil to a new 20 lt pail I have on hand.

The suction filter, below the gearbox has been removed and there is no indication of any blockage, there very minute signs of steel filings , as you would expect from any gearbox oil.The suction filter is very clean.

The HP filter has been removed and it looks very clean , and the housing has no debris in it.
When i washed the filter in fuel oil there was no discoloration of the fuel , indicating filter clean.

The next step is removing the Pressure relief valves , tomorrow.
Not known to me the 1490 , with a double hydraulic pump has two relief valves , side by side, one for each pump.
I found out this info from the service manual i have.

We will see what comes tomorrow when they are removed.
Thanks to all

DTW

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dtw
Posts: 39
Joined: Tue Nov 23, 2010 11:08 pm
Location: newfoundland canada

Re: 1490 Hydraulic issue

Post by dtw » Mon Sep 11, 2017 4:16 pm

Hello again , both prv are out on the bench , all look good and clean.
what is the procedure to increase the blow off pressure, remove shims or install shims.

Under the PRV section of the manual all that is stated is:
"The spring pressure can be adjusted by adding or subtracting shims."

So lt looks like the prv resets at 1250 psi. I would like it to reset at 1700 -1800
Any suggestions ??
DTW

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ollek
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Location: South West Finland

Re: 1490 Hydraulic issue

Post by ollek » Tue Sep 12, 2017 7:01 am

Well, I think it is obvious, compressing the spring further will increase the opening pressure. I do hope that you have not used hydraulic oil, you have to use a oil meant for transmissions. Please, do not call the oil in the David Brown transmission hydraulic oil, the hydraulic system is using the transmission oil, using hydraulic oil will lead to transmission failures. Use a oil called STOU (Super Tractor Oil Universal) or UTTO (Universal Tractor Transmission Oil).

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dtw
Posts: 39
Joined: Tue Nov 23, 2010 11:08 pm
Location: newfoundland canada

Re: 1490 Hydraulic issue

Post by dtw » Tue Sep 12, 2017 10:57 am

Thanks Ollek.
The oil I use here in Canada is a Shell TDH. ( The TDH means Transmission differential and hydraulics)

The local farm equipment supplier sells this product.

I 'll add a few shims to both prv and see what we come up with
Thanks
DTW

jazo
Posts: 773
Joined: Fri Jun 15, 2007 7:13 am
Location: New Zealand

Re: 1490 Hydraulic issue

Post by jazo » Wed Sep 13, 2017 10:42 pm

Hi, i had a similar issue with my 1394, the screw on number 13 on olleks link has a aluminium washer under it that was bypassing oil
1394 4wd
1294 4wd
30D
990x2
880
780x2
900

User avatar
dtw
Posts: 39
Joined: Tue Nov 23, 2010 11:08 pm
Location: newfoundland canada

Re: 1490 Hydraulic issue

Post by dtw » Mon Oct 02, 2017 9:29 pm

Issue solved
After a few draining of the slump, removing the PRV valves and eliminating them altogether , I bit the bullet and bought a new hydraulic pump.
It makes all the difference in the world.
I took the pump in the tractor and mixed and matched with other pumps I had, and the most I could get out of a rebuilt set of pumps was about 1800 psi.
Again at 2000 rpm the pump ramped up to 1800 psi and within 30-40 seconds it dropped down to 1150-1250psi.
Normal output is 2000 psi.
New pump installed , (i should have written down the information on it from the tag), but I forgot to do it.
The output pressure on the new pump is running around 2150 psi ( I checked with a 0-3000 gauge and a 0-5000 gauge, and both came in around the same.)
Sorry to say but it is cheaper to buy a pump from the states , built in England , shipped to Canada, price includes freight , than to buy a pump in Canada, go figure.
One last question , does anyone rebuild the double hydraulic pumps for a case 1490,I have 2 (used) and it would not hurt to have one extra on hand.
Thanks to All who replied

Have a Happy Thanks Giving weekend ,Canada and elsewhere.
DTW

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ollek
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Location: South West Finland

Re: 1490 Hydraulic issue

Post by ollek » Tue Oct 03, 2017 2:15 pm

The only thing you can do to used hydraulic pumps is changing the seals. Usually this doesn't pay of as the rotors have worn the pump housing to the extent that the pump have to be exchanged anyhow. Fitting new rotors into an old housing will result in the pressure the pump can deliver will be next to nothing. The wear of the pump is more when the pump almost constantly supplies oil under high pressure. The pump and the hydraulic system in your tractor is designed to deliver a working pressure of around 1500 psi. The max pressure relief valve is there to safeguard the complete hydraulic system, and any pressure near to the maximum, should be used for only short times. All this is common for all hydraulic systems, regardless of manufacturer. The reason for the last pump giving usable pressure and then dropping the pressure down, can be because the end plate seals in the pump are damaged. I would strip the pump down and check the condition of the seals and the wear in the pump housing.

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