I have a Cat D5C Series III #9DL01969 dozer and when it warms up... it hesitates (sometimes) going into forward gear.

Hi, My name is***** will be glad to help. We can follow up as needed on here. Professionals are not employees of the site but users of the site and help on here as time allows depending on their daily schedule.Sorry to hear you're having troubles with your machine. Where this is a hystat transmission on this machine, I would first open up your hydraulic filters to see if you find what looks like fine glitter in the oil and filter that would flag a potential hydrostatic drive pump or component failure occurring. If this is clean, the next step is to have your flows and pressures tested by connecting test gauges to the oil filter housing for your transmission filters. You will expect to see anywhere between 150 to 300 psi of pressure there. I would have your pressures and flows tested and monitored to see if those test results reveal a hydrostatic drive pump that is tired and on its way out. If you find any traces of what looks like fine glitter in the oil and filter, this would indicate a pump or component failure as I have mentioned as well.I hope you find this information helpful. Reply back with the results of these checks if any further help is needed. It is a pleasure to help anyway I can.