hi everyone im new here, didn't find thread to introduce my self, so if i'm jumping over rules sorry for that. i bought case 688B tracked excavator some 3 months ago. it stoped working when unloading from trailer. any command will just start overloadng the engine. i found out turbo was in sorry condition so i took new one, and still is the same. i could bearly turn with it, there is some more power on the boom, but thats not it. when you engage any command you can her load on engine, tracks, if u engage just one doesnt turn at all. engine is not best u see, does smoke on pipe where you pour oil in it, but i believe it something with mixing pressures in system. i changed oil, 2 hydraulic filters and still dont see any changes. what bothered me most it was little slugish when i went to see it, but when oil temp was better it worked really better so i thought it was just filter issues. now im standig and trying to find out which direction to go. any suggestions here?
ok, if anybody has any clue, where could be location of return hidraulic oil filter. i changed those two behinde cabin, is maybe third one somewher hidden? i think it could be sam on any 88 case poclain?
Welcome to HEF @tihomir The return hydraulic filter is in the top of the hydraulic tank - under a cover held in with 3 bolts. Does the engine blow any smoke out the exhaust when you say it goes under load? Have you replaced the fuel filters (including any inline filter before the lift pump) & air filter? Also, check banjo fittings at fuel delivery lines for any restriction.
thanx alrman i could't find any cover with 3 bolts on oil tan, what i could find is thing you can see on pic. is this it? no excesive smoke through exhaust when engine is overloaded, just drop of rpm and you can hear engine goes down. no matter what position of throtle is. fuel filter is only thing i still havent touch. i'll do it this week
this is second pic. so it stands biside tank and is conected to tank
also im curious what is this lever for? in what position it should be when excavator is working
It does look like a filter, possibly for auxiliary circuit such as a rock breaker - this is what the parts book shows - item #30 That looks like a swing lock - A pin to prevent machine swinging around while being transported - it should always be in the raised position. (unless being transported) If the engine blows no smoke when you say it is "under load", then it is not getting fuel. As said earlier, check fuel supply - blocked dirty filters & fittings - particularly between the tank & lift pump.
so i finaly got to excavator. took out filter and looks pretty dirty. i will look for it over the holidays, and i realy wish that will solve problems. happy holidays to everybody
Hi, have you solved your problem? I have same machines and same problem... First I try to check and clean the fuel and air system, changed the filters, but nothing happend... Engine drowns when I try to load it... Thanks!
no. i changed all hidraulics filter, in line also, fuel filter, air filter, new turbo blower, its still the same.
What type is yours, wheel or crawler? Do you have any manual for this machine? (operator, service etc.) There are a lot of switches and faucets which I have no idea what they do.
mine is crawler. i have service manual. sorry for late replay, mostly im working...
I don’t know 88 series vary well, but I remember some of them used stack of gear pumps, and some used very early version of Rexroth A8VO with very square block looking controls. Which one is yours guys? If it’s not engine problem and your pump is variable displacement - then you may have problem with torque limiters.
Try to contact gentleman with handle Sheepfoot, here on forum. He seems to know these machines!
im temporaly using wheel zeppelin so case is still on hold. what i never noticed it has foot pump and its stuck in lower position. i will try conect hoses with bypass over pump. cause it holds closed position, maybe thats problem
Have it been fixed? sounds like the electric valve for adjust pump flow.