Last time I filled up I noticed My fuel tank is leaking from the top around the sending unit. I used cork gasket material. Is there a better material I could use. I plan on dropping the tank this weekend.
If I'm not mistaken, the current replacement gasket is a thin rubber membrane. The key to sealing the tank at the sending unit is to tighten the clutch-head screws much like you would a 5-lug wheel. Alternate in a star pattern, but do not over tighten or you'll pinch the gasket and/or warp the sending unit plate. The sending unit should be snug not "jammed."
I thought the thin rubber gasket was a problem or at least what I have read, and the cork was the preferred choice. I used the cork gasket and black permatex with stainless washers and machine screws from HD, not even a hint of a leak so far.
If you have a stock type sender, you need a cork/rubber gasket. You can get a GM gasket from Greg Coleman, who has a perpertual ad in the regular classifieds (not the supporting member classifieds) at chevytalk.com.
There are other sources. Roger55 posted a pic of what looks like the right gasket a couple of days ago.
You need to use a non-hardening sealer on the gasket. The old standby Permatex #2 will work, but there's better stuff out there.
You either need to use sealant (Permatex #2 works) on the screw threads on the sender screws, and/or use the Danchuk (or locally sourced) copper sealing washers under the screw heads.
The gasket does not have an evenly spaced bolt hole pattern. It is irregularly spaced. There is a notch in the gasket and it goes at 6 o'clock, there is a dimple on the sending unit that matches the notch. If you don't have the gasket oriented properly, it will pooch and leak.
Don't overtorque the screws, even the good gasket will pooch. A thin plain rubber gasket or a thin cork gasket will pooch at normal torque. That's why you need a good gasket.
Last thing, on your EFI deal, don't assume it's the sending unit unless it's clear that it is. Jemo posted a few days ago with a similar complaint and he had problems with the hoses and fittings, and fixed it by using the right stuff.
This is an area where attention to detail and knowing what to do pays off.
Bruce cork is the way to go. I bought a roll of cork gasket at o`reillys and made my own gasket. So far so good. PLus i did away with the clutch head screws and replaced them with allen head screws.
However, If I hadn't specified that I wanted a cork one when I ordered the kit, I wouldn't have gotten it. In fact, there was a neoprene gasket in the box with the sender as well as the cork one which was in a bag with some of the other parts.
Also, they sent me screws with O-rings for the sender. Seems like they would be even better than copper washers.
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