Smorgasbord

I've been running veg oil in my saws for more than 15 years. Never had any problems, except possibly this one but I'm not convinced it was the oil itself! I think bar oil is not worth the money to be honest plus it's bound to be more damaging to the environment.

Thanks for the replies. Now that I've replaced all the parts from the pump right out to the clutch I've had no problems. The new pump is the white plastic one, the original was the black version. I have only used neat rapeseed oil in this saw since new and the first worm drive only went last July, after about 8 years of use. The saw gets used quite frequently but there may be a month or two of little use occasionally. The original black pump was a bit gummed up, but I did clean it fully and was turning freely a while ago but still I had the worm gear issue after that. All parts are correct according to manual and OEM including the correct clutch drum with the lugs to spin the worm drive. There is one other factor that may have actually been the culprit; for a while I was using sunflower oil, not rapeseed oil and I wonder if this oil behaves differently when hot? I won't be using sunflower ever again just in case...

Hello all, This is my first ever post here after lurking for years but never needed to say much! So my 10 year old 560xp, which has had a lot of use and is still running well, has started giving me a massive headache with the worm drive. Last July the oil stopped flowing for the first time ever in it's life, turns out the worm drive was worn out - thread mangled. The replacement worm drive lasted to mid last winter, then same thing - oil stops flowing and drive's thread is mangled. This then happens again several times in a row for the last few months; I'm now on my 8th worm drive since last July! I replaced the oil pump last week, but the previous pump was running fine and after a full strip-down and clean I'm confident it wasn't the source of the problem. Cut firewood for a few hours last week after replacing oil pump, then a few hours today before the oil stopped again. The parts are definitely correct for the saw and they are fitting correctly. There is no play in the oil pump and the oil flow is good, all the lines clean etc. When I put a new worm drive in it oils fine for a few hours then eventually the thread becomes mangled. I've now replaced the pump, worm drive, needle bearing, sprocket, clutch drum, clutch AND even the clutch cover - all new parts. Is there any other possible known cause for such a consistent and frequent issue like this? Has anybody else had this issue? See pic of last 6 worm drives all with almost identical wear on threads.