old Poulan Super 25 chainsaw leaking bar oil like a sieve!

[Frapp3coffee]

My dad's 1980 Poulan Super 25 chainsaw just got running again, but now it's got a new problem
Bar oil is GUSHING out automatically, it's basically spraying the chain constantly, even though it has a manual oiler button.

It never did this before. he fixed it to get it running. is this leak happening bcs he forgot a check valve or a tiny screw near the plunger or something?
Before I start tearing this old thing apart, what's the quick fix or what should I be looking for that would cause the manual oiler to fail open like this?
also, what should I do to make this kind of old chainsaw always in good condition?

 

[benchguy]

Make sure to check the oil pump and confirm that the check valve is in good condition. If the valve is broken, it could lead to an uninterrupted flow of oil. Changing out the check valve should fix the problem.

 

[Cuttingranger]

Hey, also take a look at the plunger seal and spring. If they're worn out or gone, you might get constant flow, no matter how the valve is.

 

[Alan]

Great points so far. I just wanted to jump in here because I think I can offer some help. Have you had a chance to check out the oil line routing and the tank vent? Sometimes, if the vent gets clogged or the line is misrouted, it can create a pressure buildup. This can force oil through, even if the valve is supposed to be closed. It's definitely worth a look.