Dolmar PS-7900 Air Filter Question...

[MCW]

Hi.
Bought a new 7900 a few weeks back and have done quite a bit of cutting since in dead eucalypt with both 20" and 32" bars and Oregon LGX chain. Its an excellent saw and it was info on this site that convinced me to buy one.
When cleaning the air filter however I've noticed that some wood dust (and presumably normal dust too?) has been getting through the filter leaving residue inside the filter and on and around the choke. This residue seems to be slightly oily.
Just wondering if any other 6400-7900 owners have noticed this and perceive it as a problem? I'm always worried when stuff like that gets through any filter on any engine as it can't be a good thing.
Thanks for any help.

Matt

 

[Madsaw]

Matt,
Do you mean crud like this build up in the filter? For some reason all the dolmar guys will not comment on it. This happens to be a 5100 filter here in the pic. But the 7900 do the same thing. Seems to be alot so good fit between the 2 pieces of filter. I am going to try a bit of silicon after cleaning the surface of oil residue. Then I hope not to see anymore crud on the inside.
Bob

 

[MCW]

Matt,
Do you mean crud like this build up in the filter? For some reason all the dolmar guys will not comment on it. This happens to be a 5100 filter here in the pic. But the 7900 do the same thing. Seems to be alot so good fit between the 2 pieces of filter. I am going to try a bit of silicon after cleaning the surface of oil residue. Then I hope not to see anymore crud on the inside.
Bob

Hi Bob.
That is exactly what is in my filter but your picture is to a lesser extent. You can tell by the way it is spread through the filter housing and intake that its not a leak or poor filter fit but coming straight through the filter material itself. It also seems to be a wood dust/oil type residue and is not gritty at all. I've fully degreased the filter etc now to get the crud out. I'm worried about what the rest of the intake/carb looks like
The filter certainly seems to get the bulk out but most of my cutting is dead wood with a reasonable amount of dust.
Can't complain about the saw in any other way but everyone seems to brag about the air filter set up on the 7900 and its got me a bit concerned. Not sure whether I should spray it with filter oil or not? This seems to work on my MacCulloch that has done a hell of a lot more work than my Dolmar with no dust getting through at all although that is a foam filter.
Matt.

 

[cbr929rr]

I usually spread a little grease on the plastic mounting flange of the filter, this helps alot, but doesn't completely eliminate the dust.

 

[funky sawman]

Sitting in my shop right now is 6 dolmars 5100 and 7900 all with the same problem: Blowen up do to debris getting past air filter----OK guys, choke on that on for a while!!!

 

[2000ssm6]

Sitting in my shop right now is 6 dolmars 5100 and 7900 all with the same problem: Blowen up do to debris getting past air filter----OK guys, choke on that on for a while!!!

How much for one 5100 and 7900?

 

[funky sawman]

How much for one 5100 and 7900?

Dolmar factory is sending me call tags to return the saws for credit and they are going to study the filter problem. One Dolmar tech told me that they will be coming out with a "stack filter from factory" set up in the near future. All the saws were almost new and everyone of the customers got a new saw at no charge--- NOW that is good warranty service.

 

[2000ssm6]

. All the saws were almost new and everyone of the customers got a new saw at no charge--- NOW that is good warranty service.

Yes, that is! Kudos to Dolmar!

 

[JT78]

Does your saw have the pre filter cover or the one with the holes in it. I had a little bit of this problem when I first got my saw I switched the filter cover to the one with the pre filter and have not had anymore problems.

 

[funky sawman]

Does your saw have the pre filter cover or the one with the holes in it. I had a little bit of this problem when I first got my saw I switched the filter cover to the one with the pre filter and have not had anymore problems.

All the 7900 that I've sold have the fine mesh pre filter in the cover but for some reason they are still getting debris sucked past

 

[Lakeside53]

That's why Stihl changed to the "fleece filter" about 18 years ago in the USA and Australia (and a few others). The mesh style is still sold in Europe, or as a "winter" filter here.

ALL FILTERS pass debris - if the material is smaller than the holes in the filter, it will pass though.

A little WOOD dust won't hurt the engine; sand or stone dust is another story...

 

[funky sawman]

Whatever these guys are sucking in, it is scoring the intake side of the piston!!

 

[Lakeside53]

I'd bet dust/sand from bark/drywood standing dead or charcoal etc from burnt timber...

 

[Works4me]

I'd bet dust/sand from bark/drywood standing dead or charcoal etc from burnt timber...

Standing dead is pretty much the only thing I cut with my 5100, cut some Hickory with the gritty bark. I sure would like a fix for this as I would like the saw to last a lot of years. Clean the filter everytime before I use the saw and it always has the fine dark brown dust on the inside. Tried vasoline around the base of the filter, didn't seem to make much of a difference

opcorn:

 

[MCW]

Whatever these guys are sucking in, it is scoring the intake side of the piston!!

The particle size that is getting through my filter certainly wouldn't be big enough to cause visible scoring in the bore. Mine hasn't got the pre filter though its a September 06 model.

 

[funky sawman]

The particle size that is getting through my filter certainly wouldn't be big enough to cause visible scoring in the bore. Mine hasn't got the pre filter though its a September 06 model.

Oh whatever

 

[gink595]

Dolmar factory is sending me call tags to return the saws for credit and they are going to study the filter problem. One Dolmar tech told me that they will be coming out with a "stack filter from factory" set up in the near future. All the saws were almost new and everyone of the customers got a new saw at no charge--- NOW that is good warranty service.

Any expected date for the new filteration? I'd hate to invest in the POS version

 

[funky sawman]

Any expected date for the new filteration? I'd hate to invest in the POS version

Spring of 2009:jawdrop:

 

[wkpoor]

A saw is supposed to be making chips, not dust Hahaha. I'm going to check mine tomorrow but I don't recall getting that fine dust particles around the filter. Seriously I do keep my chain sharp and pride myself on seeing large chips when I saw. My Solo ( about same as 7900) is bad about pulling chips through the starter slots. Many do reach the airbox.

 

[Sethro]

I have 3 Dolmars a 05 ,06 and a 07. I even drilled some extra holes in cover for more airflow. A little gets thru but I have burnt one up yet. I try to keep chains sharp though.