MS290 sprocket & oiler questions

[ihatesaws]

Bought a carlton bar and chain kit for €60 locally. Guy said that stihl bar is probably better but if lubrication isn't adequate any bar will wear out quickly.  Put bar on saw and area around bar is much cleaner now as oil must be taking sawdust away.  Warmed saw up and even mixed 10% diesel with SAE50 chain oil and put tip in front of timber and I could slowly see a line of oil being flung off the chain.  This is not enough however as chain got very hot after cutting for a while and oil in tank was not really going down.  I took off bar and ran saw.  Oil was coming out the hole on saw as usual but then it seemed to stop.  Can the oil pump be worn and not pump all the time or without enough pressure?  There are instructions in the stihl manual for disassembling the pump for cleaning,  Is this worth trying or should I just get a new pump?  There are no blockages in the tank or hose as I can suck oil through from the tank by attaching vacuum pump to hose where it connects to oil pump.

[ihatesaws]

Is Spud on holidays? 

The oil tank vent was blocked with the bio oil that had blocked everything originally. I was able to draw a vacuum from the oil tank.  I cleaned the vent and the oil flows better now but I don't think it's enough.   I feel the chain is much too dry still and the level of oil in the tank sinks very slowly.

[spudulike]

Not on holiday but mad busy. Yes, oil pumps can wear, there can be gloop in the bottom of the tank, the oil pickup filter can be blocked, the oil pump feed and outlet can be partially blocked, the bar oil holes can be blocked or the feed to the bar mount can be plugged....oh, and the worm can be stripped!

It is usually easier to clean and inspect every part and if that doesn't do it, buy a new pump!

[ihatesaws]

I cut off the stop for the control bolt with a hacksaw allowing it to be adjusted beyond maximum. This allows for a longer stroke of the pump piston.  It is pumping more oil now and while the chain is not very wet there is a thin film of oil on the drive links.  I will also try thinner oil in future.  That bio oil I used to use before was mixed with 4 parts water and looked and flowed like milk while this sae50 oil I'm using now is like honey. From what i've read online the saws are designed to oil badly to comply with environmental legislation.

[bmp01]

The oil pump on a saw is a fairly simple device but also a fairly pathetic vacuum device. You've seen you can suck oil through the lines with a proper vacuum pump but don't expect the pump to achieve anything like that sort of vacuum. The reason the pump falls over as soon as it is asked to pull a vacuum is because it will find it easier to suck in air past the seal....and often there is no seal,  it relys on a good fit between the oil pump shaft and the housing. With time and wear this clearance increases such that the pump can't pump anything before it sucks air in preference - ie. worn out. 

 

Another possibility - the pump shaft is not travelling its full stroke.  Maybe gummed up or the return spring might be weak,  maybe damaged or even rusted away if it's been in contact with water.

 

I'd pull the pump apart and have a look for wear and / or scoring. See what you can learn.  It's unlikely to get any better with time ....

 

BMP01

 

 

Edited April 19, 2018 by bmp01
Missing word added

[HuntingHicap]

Or buy a Husqvarna

[ihatesaws]

4 hours ago, HuntingHicap said:

Or buy a Husqvarna

Better the devil I know or in this case the boat anchor!

 

I think the pump is probably working fine and will do better now that the tank vent is open and won't have to fight the vacuum.  I've been reading and this SAE50 oil should have a viscosity of around 200 cSt.  I'm going to buy some oil with a value of 100.  I'll  thin the sae50 stuff as well by maybe 20 or 30% diesel.