O rings and gaskets

Good day all. Replacing o rings fuel pump housing and gaskets. Pic’s show some of what I’m finding. Probably a number here has experienced this. Couple questions.. is it ok to lightly apply grease on o rings ..? Any tricks to replace the plug end? It is verrrry tight. The fuel tower side has the beveled bore on the pump and looks to position ok when tightening pump back on. And with the new gaskets.. is sealant necessary? Previous pump to fuel tower gasket had sealant extremely used. Tedious to clean scrape off. This is on a 3T D7. And I was a bit surprised the new retainer seal was so much lighter built than previous. Thankful for any advice ..

yes you can use a little oring lube. or simply some light engine oil as that is what the oring seals against is oil. as for the seal apply a thin coat of no3 form-a-gasket or grease to the out side and fill the seal lip with grease. the number 3 will help it slide in use a seal driver or a socket just smaller than the OD of the seal so you dont damage it, a piece of pipe can also be used but must have all sharp edges filed smooth. be sure to start it even and square or it will warp the seal ruining it. tap gently!
if you have access to a shop press you can push it home with that. or set it up square in a vice between soft jaws or bits of soft wood tighten slowly it will go in straight provided you set it up properly and the timber and vice jaws are square.

the gaskets can be dressed with a gasket dressing such as hylomar or my go to form-a-gasket no.3. you can also use a light smear of bearing grease which works well on inspection covers that are removed regularly as it stops the gasket from sticking and you can take the cover off without breaking the gasket.
check the mating faces before installation with a straight edge such as a steel rule held on its edge and sight across the faces if you see light or there is scoring a sealant is required if bad use loctite master flange sealant 515

rtv sealants are a nuisance when over applied and often are over used when the gasket alone is enough besides there are much better products for most applications
grease works fine on cork gaskets helps stop the breaking during install remember just a light smear.

Great info trainzkid88. Thank you for sharing. Much appreciated.