Robert Kesselring
Member
Machine is a WA200PZ-6. Customer said it used to overheat maybe once every couple weeks when they worked it extra hard, now it will overheat after 20 minutes of just driving around.
Replaced thermostat, no change.
Checked fan speed against spec, fan speed is actually 50 rpm higher, verified fan is mounted right way around, air-flow seems strong. Temp drop across radiator is 15 degrees F, so about where it should be. Radiator was sent off to a rad shop last fall and cleaned as part of another repair, also, head was off and got checked and resurfaced.
Coolant temp sensor agrees with ambient temp at 72F and reads 190F when placed in recently boiling water, so I don't think it's a sensor issue. Removed and inspected water pump, no visible faults and vanes are tight on shaft. Belts look ok.
Hydraulic temp does not rise above normal, just engine coolant, so I don't think it's a hydraulic issue.
Drained oil and sent sample to lab, no coolant contamination. Pressure tested cooling system, no pressure drop and no coolant getting into cylinders. Pressurized each cylinder for 1 hour with gauge on cooling system, no detectable pressure getting into cooling system from cylinders. I suppose there might be a crack that opens up only when hot, but that's hard to test for. I've never had much success with the chemical tests that are supposed to check for exhaust gasses, I have had a lot of false negatives and false positives from them with other machines, so I don't really trust them.
Edit: Air filter looks ok. Machine is pre-DPF, so exhaust restriction shouldn't be an issue.
Any other ideas?
Replaced thermostat, no change.
Checked fan speed against spec, fan speed is actually 50 rpm higher, verified fan is mounted right way around, air-flow seems strong. Temp drop across radiator is 15 degrees F, so about where it should be. Radiator was sent off to a rad shop last fall and cleaned as part of another repair, also, head was off and got checked and resurfaced.
Coolant temp sensor agrees with ambient temp at 72F and reads 190F when placed in recently boiling water, so I don't think it's a sensor issue. Removed and inspected water pump, no visible faults and vanes are tight on shaft. Belts look ok.
Hydraulic temp does not rise above normal, just engine coolant, so I don't think it's a hydraulic issue.
Drained oil and sent sample to lab, no coolant contamination. Pressure tested cooling system, no pressure drop and no coolant getting into cylinders. Pressurized each cylinder for 1 hour with gauge on cooling system, no detectable pressure getting into cooling system from cylinders. I suppose there might be a crack that opens up only when hot, but that's hard to test for. I've never had much success with the chemical tests that are supposed to check for exhaust gasses, I have had a lot of false negatives and false positives from them with other machines, so I don't really trust them.
Edit: Air filter looks ok. Machine is pre-DPF, so exhaust restriction shouldn't be an issue.
Any other ideas?
