Does anyone know what the plastic tank looking part is in a 164 gas tank.
It is at the top and look like the filler goes into it. I am having
the tank cleaned, but they can't coat it because of this plastic part.
Can we just break this out or is it needed for some reason?

You need it in there, it stops fuel coming the neck when corning with the tank more than 3/4 full on LH turns.

While the tank is out, make sure the floor of the boot is flat and parallel to the tank.

--
69 142S Overdrive + 69 164S Manual

I think it is part of the venting system for refueling and I am pretty sure it can be removed. Just make sure the vent tube in the filler neck on the gas tank and vent tube inside the upper filler neck are clear and connected to each other with the special rubber hose.

FYI, I have those rubber hoses in stock as I just dealt with a repro gas tank fiasco on a 1976 Volvo 264 which has a similar gas tank.

The repro gas tank did NOT have the plastic tank, nor did it have the metal tube inside the filler neck. I installed the tank that way and it was very difficult to fill requiring manual operation of the fuel filler nozzle at the gas station at the lowest possible flow and even then it would auto shut off like the tank was full even though it wasn't.

I removed the tank and had the metal tube from the original gas tank transplanted into the repro gas tank filler neck along with a new rubber hose and I was able to easily fill the gas tank afterwards.
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com