Best Fuel Sender Gasket Source

[Ed S.]

Re: Best Fuel Sender Gasket Source

Thanks - will try to find it.

[Joe L.]

Re: Best Fuel Sender Gasket Source

You know, there are a lot of threads about how the replacement gaskets don't work. People state that they leak and they are not the same as the OEM gasket. I have 2 OEM gaskets. the OER gaskets are available from a lot of vendors. Summit sells one for $3.99. I am going to get one from Summit and compare its dimensions (with a micrometer) to the OEM O-ring I have..... and then report the results on this forum. Before I order one from Summit I want to ask Joe (and others) is there an alternative source I should get one from to do the comparison? Just about every vendor carries the aftermarket O-ring. Is one supplier preferred over another?

Ed-------

There are many aftermarket sources for this gasket but I do not know if the actual manufacturers differ.

Keep in mind that the differences involve more than just the thickness of the gasket. Durometer is another factor.

[Mark M.]

Re: Best Fuel Sender Gasket Source

I've measured original nos and repro o rings and all are close in size. The leak issue will appear if the locking cam goes on loose. If that can't be understood what else is there to say. The previous thread discussing this was from dec. 10 2022 titled : weird fuel leak from the sending unit on 69 . good luck

[Ed S.]

Re: Best Fuel Sender Gasket Source

I did a search of this Tech forum for the O ring part #. It came up with only 9 threads, not many to scroll through to look for someone that measured and comments on what they found. Only found one post, where a member actually compared a new repro O ring to an original that he removed from his car. Here is the link to the post: https://www.forums.ncrs.org/showthre...hlight=3825206. To my surprise, the diameter and thickness of the repro gasket were greater by several thousands than the used original. The author (James West) attributed the smaller size to "shrinkage".

[Gary B.]

Re: Best Fuel Sender Gasket Source

Ed,

Harry Sadlock provided these measurements,

NOS Thick .2385 ID 1.868 OD 2.377

Rerpro Thick .2270 ID 1.789 OD 2.277

5% smaller thickness on the repro.

Gary

[James W.]

Re: Best Fuel Sender Gasket Source

I think the the O-ring shrank after being exposed to the air after it was removed. It is/was definitely smaller than the new GM NOS that I replaced it with. The tank is back in the car and is leak tight.

James

James

I did a search of this Tech forum for the O ring part #. It came up with only 9 threads, not many to scroll through to look for someone that measured and comments on what they found. Only found one post, where a member actually compared a new repro O ring to an original that he removed from his car. Here is the link to the post: https://www.forums.ncrs.org/showthre...hlight=3825206. To my surprise, the diameter and thickness of the repro gasket were greater by several thousands than the used original. The author (James West) attributed the smaller size to "shrinkage".

[Ed S.]

Re: Best Fuel Sender Gasket Source

Ed,

Harry Sadlock provided these measurements,

NOS Thick .2385 ID 1.868 OD 2.377

Rerpro Thick .2270 ID 1.789 OD 2.277

5% smaller thickness on the repro.

Gary

Hay Gary - how's it going? So I just measured both of my NOS O-rings. I gotta tell you, measuring the ID and OD is a challenge. The rings have these small rubber nubs from the form or mold all around the ID and OD circumference. Precise measuring is difficult. I got numbers ranging from 1.8895 to 1.9001 for the ID; 2.3645 to 2.3830 for the OD and a constant 0.2400 for thickness. A few 10 thousands difference can probably be attributed to age (and caliper operator error) and shouldn't make that much difference.

All written advice states these should be soaked in oil for 24 hours before installing. Does the oil cause them to swell? Wondering if the ones I have should be stored wet with oil (and in a plastic bag)? Any thoughts on that?

[James W.]

Re: Best Fuel Sender Gasket Source

I would say store them dry in a cool, dark place. If they were meant to be stored in oil, I think GM would have packaged them that way. The NOS ones I still have are soft and pliable.

James

Hay Gary - how's it going? So I just measured both of my NOS O-rings. I gotta tell you, measuring the ID and OD is a challenge. The rings have these small rubber nubs from the form or mold all around the ID and OD circumference. Precise measuring is difficult. I got numbers ranging from 1.8895 to 1.9001 for the ID; 2.3645 to 2.3830 for the OD and a constant 0.2400 for thickness. A few 10 thousands difference can probably be attributed to age (and caliper operator error) and shouldn't make that much difference.

All written advice states these should be soaked in oil for 24 hours before installing. Does the oil cause them to swell? Wondering if the ones I have should be stored wet with oil (and in a plastic bag)? Any thoughts on that?

[Gary B.]

[Joe L.]

Re: Best Fuel Sender Gasket Source

I've measured original nos and repro o rings and all are close in size. The leak issue will appear if the locking cam goes on loose. If that can't be understood what else is there to say. The previous thread discussing this was from dec. 10 2022 titled : weird fuel leak from the sending unit on 69 . good luck

Mark-----

It's probably always advisable to replace the cam lock when replacing the gasket. The GM part, GM #3774937, is still available under the original part number. Curiously, it carried a GM list price of $0.15 in 1963. It's $11.38 today. That's inflation for you (and, also the result of this part no longer being used in PRODUCTION).

[Ed S.]

Re: Best Fuel Sender Gasket Source

Good point! I have been and will continue to store mine in a plastic bag - with most of the air pressed out before it is sealed, and then in a cool dark place. I think we have solved this problem!

[Joe L.]

Re: Best Fuel Sender Gasket Source

Ed,

If you look in your AIM, I’m pretty certain it says to soak the O-ring in motor oil for 2 hours. It’s best to be a bit careful with rubber and petroleum products, since petroleum lubricants and grease will degrade rubber. So, if the AIM says 2 hours, I wouldn’t recommend 24 hours.

For other purposes, I use silicone grease on rubber items, since silicone grease does not degrade rubber.

Gary

Gary-------


I do not know what type of rubber this gasket is manufactured from. However, since it has to be gasoline resistant, it must be a rubber that's probably resistant to other hydrocarbon compounds.

[Gary B.]

Re: Best Fuel Sender Gasket Source

Gary-------


I do not know what type of rubber this gasket is manufactured from. However, since it has to be gasoline resistant, it must be a rubber that's probably resistant to other hydrocarbon compounds.

[Wayne G.]

Re: Best Fuel Sender Gasket Source

Joe,
I recently changed out the tank fuel sender seal on my 66. The Paragon repo had a slightly larger diameter and would not seat in the fuel tank depression. Even with the tool you could not turn the retainer ring. Quanta seal was right on and sealed properly. My fuel tank is original to the car.

Wayne

[Keith M.]

Re: Best Fuel Sender Gasket Source

I believe OEM have JR on the tab?