Excessive Hydraulic foam

selftot

Active member

Equipment
L3400
Aug 6, 2025
95
124
33
Vancouver Island
My dealer replaced the rubber intake line to the hydraulic pump. I think they were grasping at straws to deal with the jerky 3 point hitch.
I have not seen any foaming in 18 years until now. It bubbles excessively when I engage the HST pedal.

The obvious response is to take it back to the dealer and get them to fix it but I have concerns about their competence (for other problems). Still waiting for the manager to call me back. Next closest dealer is 6 hours and an expensive ferry away.

I’m considering removing the new rubber intake hose for inspection and cleaning of surfaces before re-install.

Anything else I should look at first ? Is there a good way to test the (new) rubber intake hose itself ?

Oil is clear after starting tractor but looks like this after driving 20 ft. It looks bubbly and cloudy but go clear again after sitting.

IMG_2555.jpg
 

Fedup

Active member
Apr 6, 2016
343
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Winchester
You might start by tightening the hose clamps on said rubber line. That's cheap, simple, and could make a difference.
 
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number two

Active member

Equipment
B3030HSDC L2501HST
Mar 26, 2021
414
198
43
Northern Lower Michigan
Wasn't there a recall/updated hose near the left center of the tractor that would crack and suck air?
And I seem to recall many jerky 3pt complaints that were never resolved.
Good Luck!
 

selftot

Active member

Equipment
L3400
Aug 6, 2025
95
124
33
Vancouver Island
I added extra gear clamps and some grease around the hose interface to block air.
No improvement.

Is it normal for the level in the site glass to drop when the hst pedal is pushed? The level drops and oil gets bubbles. That cant be normal...

Other ideas in my head - maybe i should bypass the valves the dealer installed for 3rd function and rear remotes.

IMG_2559.jpg
 

selftot

Active member

Equipment
L3400
Aug 6, 2025
95
124
33
Vancouver Island
What is the best way to test for intake leaks (without expensive equipment).
I read that foaming Dawn dish washing liquid with a bit of glycol is effective and safe.
 

North Idaho Wolfman

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L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
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Sandpoint, ID
What is the best way to test for intake leaks (without expensive equipment).
I read that foaming Dawn dish washing liquid with a bit of glycol is effective and safe.
Why would you think soap would make a good suction leak fluid?
It's not like it's going to blow bubbles?
There is no quick intake leak detecting fluid!

If you have that large of a suction leak, wherever it was leaking would be wet when it's not running.

I bet they hooked up a remote or the third function improperly and that is causing flow issues.
 

selftot

Active member

Equipment
L3400
Aug 6, 2025
95
124
33
Vancouver Island
Why would you think soap would make a good suction leak fluid?
It's not like it's going to blow bubbles?
There is no quick intake leak detecting fluid!

If you have that large of a suction leak, wherever it was leaking would be wet when it's not running.

I bet they hooked up a remote or the third function improperly and that is causing flow issues.
Bubbles would get pulled in. Apparently.

I have a separate thread about the new valves. It was suggested they would not cause foaming. But maybe I documented the setup wrong. I’ll go take another look at the plumbing and report on the valve thread.
 

selftot

Active member

Equipment
L3400
Aug 6, 2025
95
124
33
Vancouver Island
I bypassed the 3rd function, rear remotes and backhoe is not attached.
Retraced the plumbing to confirm diagram below.

When forward is applied to HST pedal, oil level drops below site glass bottom and foams
When reverse is applied to HST pedal, oil level rises and foams.

I never monitored the level that closely before but i pay enough attention to know there has never been foam at startup or at the end of the day. Not sure what the dealer might have done...

There are no oil leaks. No spills on the floor where its parked.

How can I check for leaks in the low pressure suction lines to the pump ? Or am i looking in the wrong place.

Thanks for any tips.
Hydraulic circuit valves removed.jpg Hydraulic Block.jpg
 

selftot

Active member

Equipment
L3400
Aug 6, 2025
95
124
33
Vancouver Island
I decided to snug up the hydraulic filter a bit more.
It was tighter than i put it on in December (contact plus 2/3 as per instruction)
The shop gorilla must have had a go at it. I tensioned it correctly again but maybe the seal was damaged.
 

selftot

Active member

Equipment
L3400
Aug 6, 2025
95
124
33
Vancouver Island
Water in the oil will cause foam.
Thanks - the oil clears up after sitting for an hour. Tiny bubbles

I went thru the dealers invoice line by line. Turns out they also replaced these 2 0-rings. Just throwing parts at a theory. (their theory was air intake causes jerky 3pt)

I'll test this tomorrow with grease unless there is a better idea.

1779072868429.png
 

North Idaho Wolfman

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L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
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Sandpoint, ID
Again if any of the suction fittings are leaking then they should be wet after sitting for a while.

Oh and i think your barking up the wrong tree.
Run the loader up and down and the three point up and down without moving the tractor and see if it foams.
If it doesn't then you are 100% barking up the wrong tree and you need to look at the plumbing for the HST not the hydraulic system.
 
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selftot

Active member

Equipment
L3400
Aug 6, 2025
95
124
33
Vancouver Island
Again if any of the suction fittings are leaking then they should be wet after sitting for a while.

Oh and i think your barking up the wrong tree.
Run the loader up and down and the three point up and down without moving the tractor and see if it foams.
If it doesn't then you are 100% barking up the wrong tree and you need to look at the plumbing for the HST not the hydraulic system.
I confirmed the loader and 3pt both also cause foaming. It's just not as easy to see as the hst pedal. But full on valve openings do it.

I traced the suction lines from the tank to the pump and also thru to the other side around the HST filter. I don't see any sign of oil/oozing.

The dealer invoice lists parts for the new valves (3rd function and rear remote), the rubber intake hose and the 2 o-rings above. I'm 100% sure the problem started at the dealer as i tested for foaming before i took it in (they suggested air ingestion for jerky 3pt on the phone).

I'm not really worried about the jerky 3pt as these tractors are known for it. Just thought they might have a way to improve it.

My only concern now is the foaming.
 

selftot

Active member

Equipment
L3400
Aug 6, 2025
95
124
33
Vancouver Island
Spray your concerned fittings with a cleaner. When dry sprinkle a powder (like talcum powder) and it will be easier to see leaks.
Thanks - I tried that and left it sitting for a day and a half. Also did the HST suction pipe connections. No oil seeping visible.

After i removed the hydraulic filter, this piece of plastic was in the oil pan with the oil. I'm only 90% sure it came out of the filter / housing. I don't know how else it got in the oil pan... 1779311514460.png

I don't suppose anyone recognizes this piece (top and bottom pics). Looks similar to the plastic tab on a new container of oil but this is hard plastic and thicker.

IMG_2562.jpg IMG_2563.jpg
 

Joisey

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Kubota L47 TLB
May 31, 2015
221
144
43
Wild, Wonderful West Virginia
Does that feel like the same plastic that an oil bottle is made from? I understand it's thicker. Plastic bottles are made in a blow mold machine. A controlled size piece of hot plastic is set on the end of a metal tube that is inside of a heated metal mold. Air is applied, effectively turning the hot plastic into a balloon, which takes the shape of the hot metal mold. If not enough plastic is used, a piece such as you found will result.

When it was cleaned off of the blow tube, it could have fallen into the already blow molded bottles in the collection basket below. I worked for Wheaton plastic for a year and the plastic piece that you found looks very familiar for the reasons I listed.