hydraulic PRV

[Kenny_T]

I was pulling my cultivator with my TEA 20 and I lost lift. The arms still lift but cannot sustain the pressure to lift an implement, I can even move them down slightly with my weight. I just replaced the cylinder and the piston is in good shape. When I had the lift cover off some water got in the oil I think because it went all milky. I pulled the inspection plate and there is no leakage from above as it tries to lift the implement. There is however turbulence around the pump. Is this indicative of a failed PRV? Can I remove an replace it from the side covers or should I pull the pump? I also checked the control valve and it is not sticking or anything. Thanks for any input.

 

[Kevin OH]

everyone told me if you have turbulence in the back of the pump the preasure relief valve is stuck open.where is yours at.

 

[Kenny_T]

It must be, it's about the only thing I haven't replaced in the hydraulics yet. I'm not complaining mind you, the old girl has been worked for 60 years and I'm not half that age. These are truly great tractors, did you ever hear of a car that was still a daily driver after 60 years?

 

[Kevin OH]

no and you can still get parts for these old tractors.and if it is your preasure relieve valve stuck open,i seen a while back on here some where ther is a way to get it unstuck without having to take it out.post it on hear and who ever it was might answer you back.

 

[Ryan (MI)]

My TO30 was doing the exact same thing you described. I replaced the PRV and she was fixed. I replaced mine by pulling the PTO shaft and the block on the control fork. I didn"t drop the pump. I bought the PRV off of this site too...it was even made in the USA.

 

[Jeff-oh]

If I had a TEA I would want one made in the UK.

Jeff

 

[John (UK)]

The Relief valve does NOT stick open....that is a myth.The spring loading is too high for it to stick open...John

 

[John (UK)]

DO NOT remove the Pump until you find the leak, if you remove the Pump you will never find the leak with the Pump on the Bench as there will be no pressure to leak. I can send you leak finding information if you want it. Usual places for a leak are the Pump Side Chambers but that usually shows as lifting in a jerking movement. The top right corner and the bottom right corner can have the gasket blown at the top and bottom of the high pressure pipe. Have an implement mounted on the 3 point or there will be very little pressure and the leak may not show easily.....John
[email protected] email if you need the info.

 

[Kenny_T]

John, I see no sign of leakage when I hooked up an implement and moved the control valve into the lift position. The arms feebly try to lift the implement and I see swirling around the back of the pump. I am going to try replacing the PRV.
Thanks for the replies.

 

[John (UK)]

If it is the PRV then it must have sucked up something out of the bottom and is trying to discharge it through the PRV so it must have passed through the Pump. I have been doing these tractors for over 50 years and I have never had a stuck PRV yet, always a first time. You will need to make sure that whatever it picked up is washed out or it may do it again...John

 

[Ryan (MI)]

Made in the UK is also fine in my book...just not china, india, etc. I was sad to see Autolites are made in china...its been a while since I bought them.

 

[Kenny_T]

I Had a closer look and I saw that it is leaking from the oil gallery where the cylinder and lift cover meet.
I'm gonna use this sealant stuff my dad has that works really great, I should have used it when I replaced the cylinder instead of the crumby paper gasket that came with it.
Oh well an easy and inexpensive fix. (I hope!)

 

[John (UK)]

Sealant is not recommended because of the High pressure involved. You should use the Correct gasket without any sealant, the gaskets were always used on production and gave little trouble, any trouble that did occur could usually be traced to the fact that the torque had not been checked on the bolts periodically. When you fit the Lift Cylinder you should tighten the FRONT bolts first and then the Rear ones, otherwise the Gasket can blow. They should be tightened to 55 - 60 lbs ft on both the Top Cover to Centre Housing and the Lift Cylinder to Top Cover. Gaskets should be fitted under the Lift Cylinder at the pressure point and the other two bolts should also have a gasket under the Cylinder next to the Top Cover, to level things up, if you don't use the extra gaskets the Main gasket will be unequally loaded and will not seal properly and will blow. I don't know what type of gasket they supplied with the lift cylinder but it shouldn't be "crumby" it should be about .020" thick, the same material is used on the Top Cover to Centre housing as well, again because of the pressure involved and the shock loads to which it can be subjected....John