Dolmar 7900 over oiling.

[esshup]

Dolmar 7900. I had a problem with it being a PITA to start hot, so I took it to a friend who has a small engine shop. I had previously took it to the dealer where I bought it new, but they couldn't find anything wrong.

He tore the top side down to look at the pulse line, and it was cracked. (The saw has never been apart since new that I know of). Dunno how it cracked. Now the hard start problem is fixed but.....

Ever since new the saw has leaked bar oil when sitting for any length of time with the motor off. Leave it sit long enough and the oil tank will be durn 'near dry. There was a puddle of bar oil in the back of the truck that was about the size of the powerhead footprint from sitting 3 days.....

It was set to go thru about 7/8 tank of oil to one tank of gas (when the engine is running and I'm cutting).

So, we tried adjusting the oiler less, and it's either oil or no oil, no happy medium. Then we noticed bar oil oozing out on the cover under the muffler, black bar oil, so it has to be weeping from somewhere. Took the bar off and there was a LOT of oil on the backside of the case, not just where the oiler is.

Usually it wears a 24" bar, but occasionally it'll see a 32" bar. We made sure the oil hole in the bar was clean, and so was the channel in the bar under the chain.

Any thoughts?

 

[cgraham1]

038245061 is the oil line from the pump to bar mounting pad.
038245020 is the oil line kit that has the line and screen inside the tank.
It's most likely the one going to the tank that's leaking, but it's only about $25 to replace both. You'll have to pull the clutch and the oiler to get the lines swapped.

I've had three different Makita 6401/Dolmar 7900 saws, and they all leaked oil badly. If your oil lines are black, then it's a good idea to upgrade to the newer green lines. It fixed the problem on my saws.

 

[esshup]

Thanks. The oil lines are green. They'll get changed!

 

[blades]

All I can say is due to heat the line from the tank to the pump seems to become loose at the pump connection leaking oil at that point. Case in point Makita 6421 Home depot sell off from their rental dept. Oil pump plastic parts melted. Line very loose fit on pump. I have replaced pump assembly but ran out of line to be corrected shortly ( to access must remove clutch assembly) Another note is to check very close the line up of the oil port on the bar with the oil supply slot on saw. Lately that has not been too good with the various bar mfgs. Solution is two fold increase dia of bar oil port and grind a tapered lead in to said port that positively crosses the bar oil slot on the saw. Over oiling of the chain has never been a problem on the dolmar/makita units rather lack of same - which seems to be related to the feed line connection from tank to input of pump.

 

[esshup]

I talked to the guy that's doing the work, and he said that after taking it apart he found the first line from the tank to be black, but the line going to the bar is green. He's got new ones ordered.

 

[cgraham1]

Yep. It's usually the line going into the tank that leaks. It doesn't seem to make a good seal. Someone once told me that you could pull the line out and put a washer in there to space it back tight to the inside of the tank, but I'd just swap it out since your in there already.

 

[blades]

I saw that article also , but when I recently replaced the damaged pump on the 6421 I really could not understand where it was that a washer would help. New piece of line more effective. The heat problem is of course related to the ethanol in our fuel.