Garrik
Member
I recently bought a used PC35 with about 3,000 hours on it. I knew that it had this issue when I bought it, and I got an appropriate discount, but now it is time to diagnose and repair. I am very handy, but have zero experience with this kind of hydraulic equipment.
The machine works fine when it is cold. But once it warms up, ie once the temp gauge rises off the peg to a normal operating temperature (I have not measured the exact temp at which this happens, and I don't know if it is engine temp or hydraulic fluid temp that matters), the engine will stall if any hydraulic function is run to the limit and held there even briefly. ie, when cold, the main relief valve and related relief components seem to work fine, but when hot, something doesn't work right and the engine stalls.
I checked the idle and full throttle RPM, and they are to spec.
The first diagnostic step in the shop manual is to check the Main Relief Valve, so as suggested I measured the relief pressure when this happens, and the pressure rises to about 24 Mpa just before the engine stalls. Main relief pressure spec is 26. So that seems ok - I assume that the failure mode is when the relief pressure is too high.
My next move, based on the shop manual diagnostic flow for "Engine stalls", was to measure the differential LS pressure. When I started to look into doing that, I discovered a bunch of aluminum foil stuffed between the muffler and the main hydraulic pump. That led me to back to the shop manual, which shows (in pics) the muffler covered in some kind of insulation. That insulation is missing from my muffler. And part of the main hydraulic pump that contains the LS parts is closest to the muffler.
Has anyone seen anything like this? Does the heat shield/insulation on the muffler seem important, important enough to cause part of the hydraulic pump to overheat if it is missing?
Any hints, suggestions or guidance - esp of the form, "Oh yeah, every PC35 that I have ever seen has this issue when..." would be most appreciated.
The machine works fine when it is cold. But once it warms up, ie once the temp gauge rises off the peg to a normal operating temperature (I have not measured the exact temp at which this happens, and I don't know if it is engine temp or hydraulic fluid temp that matters), the engine will stall if any hydraulic function is run to the limit and held there even briefly. ie, when cold, the main relief valve and related relief components seem to work fine, but when hot, something doesn't work right and the engine stalls.
I checked the idle and full throttle RPM, and they are to spec.
The first diagnostic step in the shop manual is to check the Main Relief Valve, so as suggested I measured the relief pressure when this happens, and the pressure rises to about 24 Mpa just before the engine stalls. Main relief pressure spec is 26. So that seems ok - I assume that the failure mode is when the relief pressure is too high.
My next move, based on the shop manual diagnostic flow for "Engine stalls", was to measure the differential LS pressure. When I started to look into doing that, I discovered a bunch of aluminum foil stuffed between the muffler and the main hydraulic pump. That led me to back to the shop manual, which shows (in pics) the muffler covered in some kind of insulation. That insulation is missing from my muffler. And part of the main hydraulic pump that contains the LS parts is closest to the muffler.
Has anyone seen anything like this? Does the heat shield/insulation on the muffler seem important, important enough to cause part of the hydraulic pump to overheat if it is missing?
Any hints, suggestions or guidance - esp of the form, "Oh yeah, every PC35 that I have ever seen has this issue when..." would be most appreciated.