Interesting 880 "Challenge"

[Ronno6]

A friend resealed an old style 880.
Worked great for a while, til it didn't.
Chamber locking...will accept 1 pump, then no more...handle just bounces back open.
That has always seemed to be a symptom of over-oiling.
As he couldn't figure it out, he sent to me.

I disassembled, cleaned and re-assembled the Daisy.
It worked perfectly.........for 2 days in a row, then locked up.
I changed 1 chamber seal part.........
Worked perfectly for 2 days, then it locked up on the 3rd day.
I replaced the pump tube.........same result.

Now I have replaced the U-cup seal.
We'll have to see how that goes.
Those are the only parts that can cause this problem, other than maybe the chamber seal spring......
Other thoughts??
Dunno..............a new challenge for me!

[happymecanic]

Though I never had a 880 in my hands, and I don't know how the valve is made, this makes me think about a sticky inlet check valve. Had that happen on an old Cr 760 with the original Oringed check valve.

[Ronno6]

Though I never had a 880 in my hands, and I don't know how the valve is made, this makes me think about a sticky inlet check valve. Had that happen on an old Cr 760 with the original Oringed check valve.

Yessir.
The aforementioned chamber seal is the check valve.........