TO30 Hyd Relief Valve

[DuKir]

I found need to replace the Hydraulic Relief Valve on my TO30, again. After activating the Relief Valve under heavy load, the lift began to rapidly leak down and required the valve replacement. This condition occurred after no loads heavy enough to activate the valve had been applied for about a year. The fluid used in this mild climate is NAPA SAE 90, API GL-1 and has been in about one year.

I’ve replaced the valve and all’s fine. I noticed the poppet stem of the old valve protruded .022” beyond the surface of the compression spring nut whereas the poppet stem of the new valve was flush with the compression spring nuts surface. I suspected foreign material between the poppet valve and its seat.

Before disassembling the valve for inspection, I made a test fixture using a grease-gun head to pressurize the valve. The valve leaked at less than 100 psi. I disassembled the valve and found it clean, except for oil. I cleaned out the oil and reassembled the valve using the same compression spring nut position as before; this time the poppet stem was flush with the compression spring nut’s surface. Retesting, it held pressure to the rated 2000 psi. (See picture).

I suspect the valve became misaligned with the seat and the stem was binding in the spring compression nut. Have others had this problem? Any comments?

The last Relief Valve replacement was with Part #: 181087M1 that included the statement “may look different than pictured, but will fit and work the same.” I’m concerned the valve may be of poor quality.

 

[John(UK)]

Ferguson recommend that you do not attempt to adjust these Safety Valves, just replace them if you have a problem. It is unusual for the Safety Valve to give trouble, it is more likely to be the Check Valve that is on the light spring attached to the Safety Valve and it can show wear on the seat. This is operating all the time the Pump is running while the Safety Valve is not. The Safety Valve will only wear if it is being discharged continually, if you are using a 3 point mounted implement that is not restricted from lifting fully then the Safety Valve will not be operating as there is no excess pressure. Make sure that the check chains are not tight when the implement is fully raised or the Valve will blow.If, as you suspect, that there was something under the seat of the Safety Valve this will have come out of the oil which should be changed to reduce th chance of it happening again..John(UK)...fergusontractors@hotmail.com
 

[DuKir]

Thanks, John(UK).
I did replace with a new valve but my concern is if the aftermarket internet valves are the quality of OEMs; they’re much less expensive.

I know the oil in the valve was very clean and there was no foreign material holding it open. I also know it was not the check valve as there was relief valve frothing in testing and the bench test showed leaking at <100 psi.

As mentioned, I suspect the valve stem was binding in the spring compression nut (probably from lack of activation) which resulted in the stem protruding .022” beyond the nut.
 

[John(UK)]

Most of the Safety Valves that are fitted now are aftermarket parts and we get little or no problems from them, so really I don't think you need to be too worried about the quality. It would be a different story if the tractors were working now as they were intended to work. I know it is not as good as the genuine ones (neither is the price) from MF which you can still obtain and if you have any doubts about quality, that is the only way to go as they are manufactured to the same original spec. There would be no froth from a leaking check valve as it is simply a non-return valve and nothing else, any pressure in the system will hold it shut. The only external signs you would get if it is leaking is that the 3 point linkage would leak down when the Pump was not running and if you can't easily find a leak, you should replace the Check Valve/Safety Valve assy as it isn't readily seen to be leaking....John(UK)...fergusontractors@hotmail.com