Hydraulic System143Service Manual – Advance 7765 / Nilfisk CR1500TroubleshootingGeneral TroubleshootingProblem Cause CorrectionGeneral poorhydraulicperformance.Low oil hydraulic level. Check the oil level in the reservoirand add oil as necessary.Hydraulic oil temperature too high. • Check for any restrictions to orfrom the oil cooler and correct asnecessary.• Clean the cooling fins on the oilcooler to ensure adequate airflowthrough the cooler.Hydraulic oil filter plugged. Clean or replace the filter elementas necessary.Pump(s) failing. Check the output pressure from thepump(s). If below specs, replace thepump(s).Contamination in the hydraulic system. Drain, flush and refill the system.General Information Regarding Checking Hydraulic PressuresAccurate measurements are the key to troubleshooting a hydraulic system. Once you obtain accuratemeasurements you can compare them to the specifications to analyze a problem.You can use digital tachometers, flow gauges/meters or pressure gauges to troubleshoot the hydraulicsystem. The pressure gauge should have a range of 0 to 3000 psi (see the Special Tools section). The flowmeter must be rated to 3000 psi and 10 gal./min.The most convenient way to check for oil flow is to check the RPM of the motor that is performing poorly.Refer to the appropriate Hydraulic Specifications table to determine the motor RPM. If the motor speed iscorrect, the pump is producing the correct amount of oil flow. However, this does not mean that if a motor isrunning too slow the problem is in the pump.The following information should be used to check for correct motor RPM, system pressure and relief valvesettings. The readings are nominal figures and there will be variations due to manufacturing tolerancesand system oil temperature. If any reading varies greater than 20 percent, there will be a noticeable loss ofperformance and the problem should be corrected.
