Fuel filter housing

[afibbe]

The attached picture showing the top of the fuel filter holder. There are two bolts and I wanted to know what they do.

The large one will not unscrew. I have not tried holding it in a vise. I am worried about breaking the part while trying to unscrew the bolt.

I was able to unscrew the small one and the seal needs to be replaced. Where can I find a replace seal?

[wwheeler]

The small one is an air bleed which usually not needed. It just uses a copper seal ring.

It has been many years since I disassembled this unit but pretty sure the large bolt is a plug. Correct me if I wrong though. I don't believe it has a seal since it is not supposed to be removed. I did remove mine and just used a thread sealant when it was reinstalled. I took the plug off to be plated.

[MikeSimon]

Sometimes, holes are drilled into cast parts that are needed for machining internal passages. They are then plugged.

[jim 56]

I put a pressure gauge in where the large screw is and it helps me troubleshoot fuel related problems