Mine of the same vintage has a check valve in the tank where the pipe
from the compressor attaches, looks like a pipe fitting but is the check
valve. When it went I cut the pipe & installed a compression fitting
type inline.

Same experience here on a 50 year old IR T-30, including the same
symptoms the OP describes. Grainger has replacement checks, though in
my case the OEM check was much easier to install, and worth the extra
cost in avoided time and aggravation.

BTW, any old check valve is not going to be a suitable replacement.

--
Ned Simmons- Hide quoted text -

- Show quoted text -

THanks for the replys. "BTW, any old check valve is not going to be a
suitable replacement" - are you referring to the flow rate of the
check valve or is there something else I need to pay attention to.
After reading the responses, I was planning on buying one from
McMaster (note: I have not yet looked to see if they have one w/ a
suitable flow rate).