Control Valve & Pinion Test

Connect a 100 psi (7 kg/cm² ) pressure gauge into pump return line. Start engine and let idle. Pressure reading should be approximately 40 psi (2.8 kg/cm² ). Turn steering gear left and right a small amount.
CAUTION: Excessive turning of steering gear will cause damage to pressure gauge.
Pressure should increase equal amounts as wheel is turned in either direction. A slight fall in pressure, occurring before rise in pressure, indicates a defective control valve. Stop and then restart engine. Check that steering does not kick to one side.
If system pressure readings were not to specifications, connect Shut-Off Valve (JD. 10-2) between pump and pressure gauge. This will isolate steering pump from steering gear and determine if problem is in gear or pump. See Figure.
CAUTION: DO NOT keep shut-off valve closed for more than 5 seconds at a time, otherwise fluid will overheat and damage to system could occur.
With shut-off valve open, start engine and allow steering fluid to reach normal operating temperature. Close shut-off valve. Repeat pressure tests.
If pressure is 1100-1200 psi (77-84 kg/cm² ), fault is in steering gear. If not, fault is in pump. See OVERHAUL in this article.