Stihl BR420 Issues

[sundance]

My BR420 is acting up this year. Not coming up to speed. I'm getting oil on the air filter (looks to be coming from the mix but not at all sure how). Also getting oil leakage out of the blower housing.

Not making much sense to me how the oil is getting on the filter. Lots of leaves left to blow, if I can't figure something out I'll be in the market to replace early nest week.

Thanks for any thoughts.

 

[DND 9000]

The oil may be left from the spitback of the carburetor venturi. That is normal if it is not to much. In your case it seems to be to much. A reason for this can be a worn piston and piston rings. That can also be a reason for the bad speed you descripe. A clogged muffler can also be the reason for the bad speeding. The oil on your engine housing can come (depending where it is) from leaking cranckcase seals or the seal between the case halves, leaking fuel lines and so on. Your blower should be properly checked in a qualified workshop. It should also be verified if your piston and cylinder are scored or not.

 

[Mad Professor]

Check the spark screen on the muffler. I've got a BR400 for many years now and had to remove the screen to clean many times. Didn't have the oil spitback but the blower would not rev at all and hard to start. This is 25 year old blower and never another problem with it. All rubber parts still original.

If you have a real leak that needs to be tracked down.

 

[sundance]

Check the spark screen on the muffler. I've got a BR400 for many years now and had to remove the screen to clean many times. Didn't have the oil spitback but the blower would not rev at all and hard to start. This is 25 year old blower and never another problem with it. All rubber parts still original.

If you have a real leak that needs to be tracked down.

@Mad Professor : Found the clogged spark screen before I saw your post. You nailed it, cleaned and burned the screen and running well now. Exhaust port was a bit of a mess as well. Makes me wonder about the muffler (420C model). Any good way to clean out the sealed unit?

 

[Mad Professor]

@Mad Professor : Found the clogged spark screen before I saw your post. You nailed it, cleaned and burned the screen and running well now. Exhaust port was a bit of a mess as well. Makes me wonder about the muffler (420C model). Any good way to clean out the sealed unit?

Does that muffler have a catalytic inside?

You might try heating the muffler with a propane torch to "cook" out the residue. You'll have to repaint it.

I know people have put sealed mufflers in the hot coals of a fire also. You have to be careful you don't melt/damage it

 

[sundance]

Yes, claims it has a catalytic inside. Makes me hesitant to try "cooking" it.

 

[Mad Professor]

Yes, claims it has a catalytic inside. Makes me hesitant to try "cooking" it.

Try asking this in chainsaw forum. The folks there have lots of knowledge about sealed and cat mufflers