Stihl FS400

We have a fairly old (pre 2002) FS400. I have recently noticed that there is a build up of oil (even though its a 2 stroke) around the base of the exhaust. It is covering the base of the plastic cover that covers the exhaust. I will be stripping the plastic covers off to find where the leak is. I think its the exhaust gasket but won't be certain until i strip it down.

Here are pics of both of our FS 400 and 450. Both have oil build up around the exhaust. No running problems except the 450 can be a bit of a pain to start first thing. The 450 also leaks fuel out of the carb/air filter but only when it is being stored. The first 6 pics are of the FS400. The other 3 pics are of the FS450.

I initially thought that you had a problem with "Spooge". That however looks like unburnt spooge most likely linked to the fuel leak you mentioned. I would hazard a guess that the inlet needle on the 450 carb is leaking, possibly the 400 as well. Should hold 5psi on the inlet pipe for a fair while, if not swap for a new one.

Are both sides of the cylinder wet with oil or just the exhaust side? Replacing the exhaust gasket should in theory be easy enough but I have had several exhaust screws twist off on these bigger Stihls and yours have been there for a year or two.

Out of interest what attachment are you running. If ours are on blade work they will put oil out of the exhaust as you can't load them up. 3.3mm Stihl black cord will soon burn it off after though.

I initially thought that you had a problem with "Spooge". That however looks like unburnt spooge most likely linked to the fuel leak you mentioned. I would hazard a guess that the inlet needle on the 450 carb is leaking, possibly the 400 as well. Should hold 5psi on the inlet pipe for a fair while, if not swap for a new one.

Are both sides of the cylinder wet with oil or just the exhaust side? Replacing the exhaust gasket should in theory be easy enough but I have had several exhaust screws twist off on these bigger Stihls and yours have been there for a year or two.

Out of interest what attachment are you running. If ours are on blade work they will put oil out of the exhaust as you can't load them up. 3.3mm Stihl black cord will soon burn it off after though.

Just the exhaust side and using 3mm on a quad auto cut head. We use metal heads for the much heavier stuff but dont rag them to death when on metal heads as that can cause the damage to the piston.

Stripped both strimmers right down yesterday and found why there was spooge around the exhaust. Both exhaust gaskets had completely gone. Got two new ones and steam cleaned both strimmers. Will check for anymore spooge leakage over the next few weeks.