Construction and other equipment - I40 Backhoe- Leaks Down

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I40 Backhoe- Leaks Down

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Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=20320
Printed Date: 21 May 2025 at 3:37pm
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Topic: I40 Backhoe- Leaks Down

Posted By: easygoin4
Subject: I40 Backhoe- Leaks Down
Date Posted: 04 Nov 2010 at 6:21am

I have an I40 loader/backhoe and was wondering what causes the boom to sag down or drop after few minutes. The bucket and arm slowly lossen up after some time. I know this is not a new machine and know nothing about hydraulics. The front loader will stay up for ever. When I got her I had to replace the seals in the boom cylinder it leaked so bad- and that it fine now.

I was wondering if it could be the levers on the hoe - or that whole valve body thing with the levers that needs redone.

I am sure the seals or rings are not available so I would have to research to find a match. Was thinking of taking it apart for the winter- but not sure what I will get into.

Any advice?

Thanks

Replies:

Posted By: Ron S/IL
Date Posted: 04 Nov 2010 at 6:27am

I would say that the valve body is worn to the point of leaving the oil bypass. I think you could rebuild or have rebuilt. You said you replaced the seals in the cylinder, did you replace the internal seals. It could also be bypassing there. Good luck.

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Ron Stork
Co-Owner Sign Solutions and Promotions.
We can custom make signs, decals and any promotional items you may want.

Posted By: easygoin4
Date Posted: 04 Nov 2010 at 6:34am

I had the whole cylinder apart- what a learning experience. From what I remember I did piston seals I think you call it, and all the o-rings that were inside. Wanted to do them all so it would last. Seems to have worked- when I got her it poured fluid out near the cyl. rod and now it does not.

I have no leaks on any lines or drips anywhere on this unit.

I am just hoping if I take it apart- I will solve the problem. I do have all the manuals for this unit so that will help on assembly.

Thanks for the input..

Posted By: easygoin4
Date Posted: 04 Nov 2010 at 6:37am

Does anyone have an idea what it would cost about to send the whole thing for rebuild? It has 2 shorter levers and 4 larger ones. I am not afraid to do it- but if the price is fair- I would send it out. Just did not know if it would be hundreds of dollars or not.

Thanks

Posted By: Ron S/IL
Date Posted: 04 Nov 2010 at 10:26am

I know a mechanic that does that I will ask him about this and let you know. Ron

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Ron Stork
Co-Owner Sign Solutions and Promotions.
We can custom make signs, decals and any promotional items you may want.

Posted By: Coke-in-MN
Date Posted: 04 Nov 2010 at 5:11pm

I would say re-do the piston seals and be sure they are good as is the bore , also there is a "0" ring under the piston to seal it to the rod. Check it out by raising the hoe and then removing the hose on the other end of the cylinder , (non pressure side) check it for oil coming ferom pressure side leaking down.

Unsure if it has "V" ring packing or square rings / also if backup ring on piston are not on right side they sometimes leak. Piston leak is probably the cause if it dro[ps fast..

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Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something.
"Challenges are what make life interesting; overcoming them is what makes life meaningful."

Posted By: pineyjd
Date Posted: 07 Nov 2010 at 1:38am

My I40 leaks thru control slightly,this lets the boom drop. I rebuilt hyd eqiup back in 60's in factory equip. & it was'nt complicated.

Do you have chains to hold boom up when not using or do you leave boom out/down ?

Posted By: easygoin4
Date Posted: 08 Nov 2010 at 7:00am

Yes I do have HD chains. I think I may get into the whole valve or lever assembly this winter. She leaks down probably in about 20-30 min. from full up to the ground.

However the loader will stay up for days..

Thanks for the advice..

Posted By: Coke-in-MN
Date Posted: 08 Nov 2010 at 7:03am

If that is the only valve leaking down, I would check the cylinder closer. Had one hoe where packings were backwards and it leaked down fast.

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Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something.
"Challenges are what make life interesting; overcoming them is what makes life meaningful."

Posted By: easygoin4
Date Posted: 08 Nov 2010 at 7:13am

Actually outriggers leak down also pretty fast- constantly having to adjust them up.

And I know the bucket does drop too.

That is what lead me to believe the whole vavle assembly needed to be redone.

Posted By: Coke-in-MN
Date Posted: 08 Nov 2010 at 7:30am

When I resealed the valve body on my HD4 I just bought the "O" rings instead of the kit, got them through MINNPAR and was cheap way to solve loader problem of dropping.

As they were a standard size , you could just pull one and match it

Posted By: easygoin4
Date Posted: 08 Nov 2010 at 7:34am

Exactly what I was thinking. Sounds easy just hope it will be.

I think the biggest problem may be getting the unit off.

Thanks

Posted By: pbqc3803
Date Posted: 31 Jan 2019 at 12:57am

Chris,
Did you get your valves fixed? Did this help or was it the seals on the cylinders?