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100 1hdt-fte power steering bubbles

Paul80-100

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Jan 24, 2023
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As title suggestes 100 series 2002 getting bubbling in pas tank and heavy steering but not all the time . Some times steering normal then further around go with lock gets easier and harder as if preasure issue.

The vehicle is new to myself and I believe this could be a existing issue as I can see the pas pump has been of at some point as not been fitted with correct sealing washer and just rtv sealant to block. Also appears to have a new steering rack installed very recently.

From what I can figure it would appear air is in system to give the bubbles but where it's getting in is anyone's guess as cant seem to see no visible leaks even though was previously little wet around area presuming from pas coming out the tank itself.

Could it be the pump or any known common issues applying more revs does not make steering easier.

I happen to come upon a valve that some talk about preasure relief valve . Are these commen and would a failed one give these symptoms.

Bit reluctant to just go straight to the pump as am guessing that's what was checked before replacing rack so just crossing other possible causes first

180k on car 1hdt-fte

Thanks
 

SteveJB

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Don't know about issues with the pas but might suggest jack up the front so that the wheels are off the ground then with the engine running slowly turn the steering wheel left to right making sure there is enough fluid in the pas tank do this several times side to side don't hold the steering wheel on the limit stops where its making a squealing sound for too long cheapest thing I can think of for you a much more knowledgeable member may have some other ideas oh and check your tyres for the correct pressure
 

Shaner58

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HI,
I had similar issues and mine is a 2002 HDFTE as well. I cheated and put some stop leak power steering fluid into the tank. Have not had an issue since. gone is the bumpy steering . I only did this as I was quoted some huge price for a replacement hose on the pressure side. It took a couple of hours of around town driving for it to completely settle.
 

Grimbo

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great_britain
Sounds like the pas pump is sucking air and cavitating.....
A leaking hose on the pressure side would be obvious but on the suction side it may not leak oil ..... check the supply hose from the reservoir down to the pump... is it a metal pipe with a flexible part ? as these get older the crimp where the flexy is joined to the metal can weaken and allow air in . A good test is to see if you can turn the flexible hose on the solid pipe....if you can then that's a possible source of air ingress .....also check whatever seals the supply hose as it joins the pump
 

Odin 8

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Bubbles in a hydraulic pump circuit are created by cavitation. This is the pump impellors chaffing on the wall of the pump, getting hot and boiling the oil. The pump is worn due to a blocked filter and contaminated fluid.
A power steering circuit is a pressurised system, it cannot suck air in.
 

Grimbo

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great_britain
"A power steering circuit is a pressurised system, it cannot suck air in."
It has a separate reservoir mounted above the pump and pipe work leading to the pump ....the reservoir isn't pressurised and I'm not aware of a PAS filter .
In the world of tractors and gear pumps you are correct that a worn pump will cavitate under load with a blocked filter.....
I still think as the OP says "It's a little wet where the PAS comes out the tank" that's the first thing to check
Odin 8 ...is that a 42 series LP in your picture ?
 
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Odin 8

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The pump is gravity fed from the resavoir. The resavoir lid must be allowed to breath, but any hydraulic system with a gravity fed resavoir does operate under a slight pressure created by the filler cap. This is to push the oil down into the pump. The pressure is only a couple of PSI above atmospheric pressure, but enough to maintain the supply to the pump. A blocked or faulty cap can create pump cavitation as the demand for oil to the pump cannot be maintained. This often creates the illusion of 'air being sucked in'.

"42 series LP in your picture"? Which picture, not sure of your question.
 

Paul80-100

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Just to update the thread so for future reference of anyone searching . It turns out that the pump itself was at fault and must of been the culprit for dragging air into the system.

Fitted new pump cleaned out the reservoir and all is good no more air in system and all is good .
 

Grimbo

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great_britain
Glad you sorted it .
""42 series LP in your picture"? Which picture, not sure of your question." Odin 8
Your profile picture shows what I thought was a Case IH 4200 series tractor ?
 

Odin 8

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Its a David Brown 1590 Commerative Edition, one of the last off the line in Mltham. Straight six cylinder diesel loader tractor. Where the picture was taken overlooks the old Mltham factory.
Most of it then went to Doncaster and got the Case IH treatment, as you probably know.
 
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