Thanks for the reply; serial # H2X352P02313 with Perkins diesel engine. Our Lindes have the foundry package with fire retardant hyd fluid (Quintolubric 888-68 syn. ester type fluid compatible with mineral base type hyd fluid and approved by Linde for use in our trucks). We change the fluid and filter every 1500 hrs which is factory required for units with an extended drive train warranty. I scheduled the local Linde dealer to come out to do the presure testing; but they are having trouble showing up. I contacted the factory; they told me I need to purchase a $1600.00 presure test kit in order to properly test this system. They also sent me a "quick reference check for hydro testing form to be filled out and returned to them. In our case we need to rely on our local Linde dealer support in order to properly troubleshoot this problem; thanks for your help and response; Dave.