Hi Guys, I have a 307b with about 4500 hours on her good all round machine digs well I did a full service when I first got it it has the Mitsubishi 4m40 non turbo engine. however recently I have noticed that after it gets warm it lacks power to turn with the tracks needing a bucket down manoeuvre to turn the track frame. but when the hydraulic oil is cold (more viscous) it seams to turn on the levers !!!! Any idears ? regards Jason
Check pressures at main pump. Possibly needs to be rebuilt. Can be other issues, I would start with pump.
The swivel is leaking. Later Bob
Unless you are 100% sure that the swivel seals are recently replaced, do that as a first action and go from there.
is that a big job ? sounds involved. it happens to both tracks when the oil is warm that's what made me think it was not the pump or track motors. however there is no power loss from the arm so unless the tracks are run from a separate pump then I would have thought the pump was ok. I was wondering if it was a valve of some sort oil leaking round when it gets warm. do you have any idea where I could get a pdf workshop manual ? thanks again Jason don't know what I would do without this forum !!
I would recommend the swivel seals as Eriksson said! :thumbsup
Ditto with others, I've done a couple of 307B with same problem, loss of tracking power but no loss of digging power, swivel seals is the first place I'd go.
hi guys, got the swivel/king post off inside are 9 seals but they look ok I cant see if they are warn ? anyone got a measurement on depth of seal so I can see if it need new ones as the new seal from cat uk are £30 each !!!!!!!
It's not so much the measurement of the seals, it's their "softness", that's what makes them seal to the centre spindle. Older seals will be a mid-to-dark brown colour and hard. New seals will be a pale cream colour and soft. Can you post a photo of the seals you removed from the swivel..?
Hi nige They were dark blue in colour and harder than I expected I have changed them all !!!! £300 later the new ones were a lighter blue and softer. The machine seams a little better but I don't think quite right if I move one track control forward and one back it won't turn a 360 is there anyway of turning the pump pressure up ? Thanks again Jason