Had a quick check on sis in regards to bleeding the implement pumps and it seems to only mention operating the machine which seems a little contradictory. Four test points off to the right are not letting oil through although I'm sure they are case drains. The big rig is definitely cavitating the pumps just from the noise when operating. Any tips? Cheers
A few things to check. The implement pumps are located higher than the tank therefore it's imperative that the tank is correctly pressurized when the oil is hot or the pumps can potentially cavitate. Also for this reason the implement pumps can't be bled. If the breaker/relief valve next to the filler cap (located under the front RH platform) has not been replaced recently then replace it. We used to change them every 2000 hours as part of the PM oil & filter changeout. There is a new Part Number for the valve, check SIS for Service Magazines or whatever listing the new number - it's something like 358-xxxx IIRC. Have you tried removing the high-pressure screens and inspecting them for the presence of metal (esp. bronze) particles. There is one of them behind each implement pump. Also, and here's the hard part, you're going to have to dig into the implement oil tank to check the suction baffles for the pumps. They have/had a nasty habit of failing due to vibration. No other way to do it unfortunately. Lastly, what temperature is the implement hydraulic circuit running at and at what ambient temperature..?
Hey nige. Honour mate read alot of your stuff in a short time I been on! So she has a brand spanking breaker up the top. All high pressure screens were cleaned during the service (4000hr) Didn't dig to far into the tank as we didn't find any particles in the screens. And the hydraulic oil was running about 75 deg C at outside temp 40deg C. A old guru came in and said to crack the bolt on the sight glass. Actually seemed to work plus getting the oil got on relief quite a bit.
At 40 DegC ambient you're going to borderline for cooling everything, not just the implement hydraulics. My last gig with 994's was with ambient temps in the mid-30's and we battled in those conditions. How clean is the radiator/cooling package..? And before you ask yes you are going to have to partially disassemble it (remove the a/c condenser and the hydraulic/PT coolers at least) in order to clean it properly - you can't just hit it from the outside with a pressure washer and hope for the best. Have a rummage round in SIS, I recall seeing a recent (July 2017 IIRC) Special Instruction for installing an additional cooler package. there may also be some Service Mags on the same subject. i recall the issue of the indicated level in the sight glass. if you examine the hoses that connect the sight glass to the tank you'll find one where (unless you're very careful) it can have a "dip" in it for want of a better word that collects an air bubble. That then leads to completely wrong indications in the glass of the oil level in the tank. I never heard of it affecting pump suction though. You are using SAE 10W hydraulic oil in the inmplements I assume..? Also it's worth checking that the tank is actually buillding pressure, despite the new breaker relief valve. Try pushing in the button on the valve after the machine has been working for a while. There should be quite a rush of air coming out of it, if not you'll have to investigate why. No obvious hydraulic leaks in the tank/pumps area on the front end I take it..? BTW the HP screens are NOT a regular PM maintenance item. They should usually only be removed and cleaned if you actually suffer a pump failure.