Saftey valve question

BigDanT

Member
Reinstalled pump after putting in a new NAA piston and rings, cleaned pump and housing, new gasket set, new CFP. readjusted linkage with Zanes jig and added new 134d oil I noticed the safety valve sitting on the work bench...crap...I thought I would see how it did and go from there...it will lift a 5' grader box just fine. will even hold it there for days, but it can't lift a 6' disc. it tries but just can't do it...so here is my question...can a bad safety valve cause it not to lift a heavy load or is there something else wrong here? Thanks Dan
 
Just to clarify, I meant to say the new safety valve was sitting on the bench...the old one is still in there. Dan
 
(quoted from post at 18:01:11 05/13/13) Just to clarify, I meant to say the new safety valve was sitting on the bench...the old one is still in there. Dan

I was real confused there for a minute. I hate doing that...

Anyway, pressure relief valves can get sticky from rust and debris and not fully close. If it sticks partially open it decrease the amount of total pressure built, limiting you lifting capacity. Its dumping fluid straight back to the sump instead of sending it to the cylinder. It should bleed off overtime as well.

Your new one should fix that. You can do it without removing the pump, but you will be hugging your transmission and cussin for about an hour
 
Open the inspection plate and look for turbulance behind the pump when trying to lift the mower.
 
JC, I tried it with the pump still in there...only took about 2 minutes before I was cussing...decided it would be a lot less aggravating to dump the oil, pull the shaft and drop the pump...anybody need a stubby little 11/16 wrench...thanks for the help. Dan
 
HCooke...funny thing..I saw that and mistook it for the PTO shaft turning..I'll know better next time. Thanks
 
(quoted from post at 21:27:01 05/13/13) Safety valve and pressure rellief valve are two separate components
epends on what tractor model we are dealing with........so far, everybody just made assumptions. :roll:
 
(quoted from post at 20:57:28 05/13/13) Reinstalled pump after putting in a new NAA piston and rings, cleaned pump and housing, new gasket set, new CFP. readjusted linkage with Zanes jig and added new 134d oil I noticed the safety valve sitting on the work bench...crap...I thought I would see how it did and go from there...it will lift a 5' grader box just fine. will even hold it there for days, but it can't lift a 6' disc. it tries but just can't do it...so here is my question...can a bad safety valve cause it not to lift a heavy load or is there something else wrong here? Thanks Dan

The simple answer is yes. How heavy is the disc? Connect a pressure gauge to the test port and see if you are getting 1500 PSI. If you are the disc is simply too heavy for the 3pt. If the pressure is less than 1500 PSI you have insufficient pressure - possibly caused by a weak pump and/or a leaking relief valve.

The safety and releif are two separate valves on the NAA and later system.

TOH
 
TOH...the disc is a little beefy but, my 2N lifts it OK. I will install the new valve and test the pressure, hopefully that will do it. Thanks for the help. Dan
 
(quoted from post at 07:31:17 05/14/13) TOH...the disc is a little beefy but, my 2N lifts it OK. I will install the new valve and test the pressure, hopefully that will do it. Thanks for the help. Dan

If your 2N lifts the same disc you have a pressure problem - hopefully the relief valve fixes it.

TOH
 
when doing TOH's pressure test. also look for leaks.. top end might still be leaking.. etc. with a low volume pump, leaks can kill lifting power.. etc.
 
SG...I worded that wrong, meant to ask is there a difference between a safety and relief valve or are they same assembly...Part# 8n638 is what I got. Thanks
 

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