Fuel Sending Unit Gasket

[Michael C.]

Can someone tell me what is the correct orientation of the fuel sending unit gasket / o-ring? Should the inside tab line up with the indention as shown in the attached photo? There is a slightly smaller indention on the opposite side of the unit at the electrical connection. I know that the gasket goes between the tank and the sending unit. I left the gasket off just to get a clear photo.

Does anyone apply anything to the gasket to assure a good seal?

Thanks and Merry Christmas.
Mike

[Larry M.]

Re: Fuel Sending Unit Gasket

Can someone tell me what is the correct orientation of the fuel sending unit gasket / o-ring? Should the inside tab line up with the indention as shown in the attached photo? There is a slightly smaller indention on the opposite side of the unit at the electrical connection. I know that the gasket goes between the tank and the sending unit. I left the gasket off just to get a clear photo.

Does anyone apply anything to the gasket to assure a good seal?

Thanks and Merry Christmas.
Mike

Don't believe orientation matters. Use no sealant. Soak in engine oil overnight or use Vaseline to coat the o-ring.

The most important things are to use a GM rubber o-ring/seal and a GM metal retainer (or reuse the old one). The repro o-rings and retainers generally don't fit as well, and can leak. Search archives for details. If you must use a repro o-ring, mike the OD and compare against OEM. Don't use if thickness is different. Then re-use the metal retainer.

Larry

[Michael G.]

Re: Fuel Sending Unit Gasket

Can someone tell me what is the correct orientation of the fuel sending unit gasket / o-ring? Should the inside tab line up with the indention as shown in the attached photo? There is a slightly smaller indention on the opposite side of the unit at the electrical connection. I know that the gasket goes between the tank and the sending unit. I left the gasket off just to get a clear photo.

Does anyone apply anything to the gasket to assure a good seal?

Thanks and Merry Christmas.
Mike

Merry Christmas to you and yours Mike. I've installed many of these over the years and do believe there's no specific orientation of the gasket. As Larry stated and very important to use a quality gasket. Couldn't say if the one's I've used were GM however there are some that are thinner (cross section) in diameter and will not seal. The correct gasket is physically thicker than it's thinner counter part.

[Michael C.]

Re: Fuel Sending Unit Gasket

Thanks Larry and Michael. The new gasket isn't GM and I'm afraid it might actually be too thick. I might end up putting the old one back on. When a leak appeared around the sending unit I assumed the gasket had deteriorated, but I found the nut holding the electrical terminal a bit loose. I've tightened the nut and might back it up with sealant on the inside. The old retainer ring looks great after a soak in EvapoRust, so I'll definitely reuse it.

[Michael G.]

Re: Fuel Sending Unit Gasket

Nothing like a new gasket Mike. Obviously will take a little effort to put locking cam into place.

[Roger P.]

Re: Fuel Sending Unit Gasket

Hi Mike. I had the same issue on my '65 recently and also thought that the O-ring had deteriorated after only 5 years. I found that the sending unit electrical terminal retainers had cracked (repro unit with push-in type plastic retainers). I found one of the last Fargo repro units available with threaded electrical terminal retainers so they could be tightened in the future if necessary. However, when I went to install the new unit, it wouldn't tighten properly because the new O-ring gasket was visually thinner than the old one. Since it was only 5 years old and appeared to be perfect, I cleaned it and soaked it in motor oil. Thankfully, it tightened nice and snug. You definitely have to look carefully at the repro stuff made these days! Merry Christmas, Roger (50141)

[Michael C.]

Re: Fuel Sending Unit Gasket

Thanks for the comments Roger. I'll soak the old gasket tonight and have it ready in case the new one is too "fat." Mike

[Roger P.]

Re: Fuel Sending Unit Gasket

Thanks for the comments Roger. I'll soak the old gasket tonight and have it ready in case the new one is too "fat." Mike

Mike, I think you will find the new O-ring to be too "thin"... but either way, you'll be ready with the old gasket just in case. Good luck, Roger (50141)

[Patrick B.]

Re: Fuel Sending Unit Gasket

Can you still get GM gaskets and retainers?

[Mike E.]

Re: Fuel Sending Unit Gasket

I just put a new sending unit and tank on my '65 chassis last weekend. Mine came with the O-rings and with some paperwork claiming that it's compatible with E10 fuels. Which is probably a good thing. Installation was a snap because I few months earlier I picked up a Kent-Moore J-23346 tool on Ebay for $25. Most of the Corvette supply stores sell a tool for installation for about $15-$20. It doesn't look as robust as the KM tool. I'm not sure how well they work.

Mike

[Larry M.]

Re: Fuel Sending Unit Gasket

Can you still get GM gaskets and retainers?

Pat:

I purchased mine from DR REBUILD a few years ago, and he still had old GM stock on his shelves in the factory sealed plastic bags. I don't have the GM part numbers handy, but can probably find them if needed. Then we can check GM availability. I am sure they are still out there somewhere.

I was not happy with the o-ring and retainer supplied by Quanta with my gas tank...............but the OLA tank was just fine.

Larry

LATE EDIT: The metal retainer is Group 3.107 and GM # 3774937. It is still available from GM, although it appears that you might need to order a pack of ten. Cost was about $1/each. The rubber o-ring is Group 3.112 and GM # 3825206. It is no longer widely available from GM, although the internet has a number of places that still have old stock. It appears that this rubber o-ring was also used for other Chevrolet and GM vehicles. It shows up for Camaro, Chevelle, Impala, Buick, Olds, and a few others. So suppliers for these marques are also a potential source of NOS. Just Google the part number for more info.

[Patrick B.]

Re: Fuel Sending Unit Gasket

Pat:

I purchased mine from DR REBUILD a few years ago, and he still had old GM stock on his shelves in the factory sealed plastic bags. I don't have the GM part numbers handy, but can probably find them if needed. Then we can check GM availability. I am sure they are still out there somewhere.

I was not happy with the o-ring and retainer supplied by Quanta with my gas tank...............but the OLA tank was just fine.

Larry

LATE EDIT: The metal retainer is Group 3.107 and GM # 3774937. It is still available from GM, although it appears that you might need to order a pack of ten. Cost was about $1/each. The rubber o-ring is Group 3.112 and GM # 3825206. It is no longer widely available from GM, although the internet has a number of places that still have old stock. It appears that this rubber o-ring was also used for other Chevrolet and GM vehicles. It shows up for Camaro, Chevelle, Impala, Buick, Olds, and a few others. So suppliers for these marques are also a potential source of NOS. Just Google the part number for more info.

Thanks for the tip. I called Dr Rebuild today. They have the o-rings in their caralog for $3.50. I asked if they were real GM o-rings or aftermarket. She said they would call back after checking them. They called back and said they had real GM o-rings but the price was now $12.50. I ordered 2.

[Patrick B.]

Re: Fuel Sending Unit Gasket

Thanks for the tip. I called Dr Rebuild today. They have the o-rings in their caralog for $3.50. I asked if they were real GM o-rings or aftermarket. She said they would call back after checking them. They called back and said they had real GM o-rings but the price was now $12.50. I ordered 2.

I just got an angry letter from Dr Rebuild regarding my post. He said the online catalog was from 2008 and the price had risen gradually over the years not as a result of my request for only real GM o-rings. He said he would not check his stock until I edited my misleading message and that there was doubt if he has any stock remaining. He also made a point of telling me that he quit NCRS 5 years ago after being a long time member. At this point I don't really expect that he will honor my order. I am going to Florida until February so I will not know until then if he sent me the o-rings. I will follow-up then.

[Larry M.]

Re: Fuel Sending Unit Gasket

I just got an angry letter from Dr Rebuild regarding my post. He said the online catalog was from 2008 and the price had risen gradually over the years not as a result of my request for only real GM o-rings. He said he would not check his stock until I edited my misleading message and that there was doubt if he has any stock remaining. He also made a point of telling me that he quit NCRS 5 years ago after being a long time member. At this point I don't really expect that he will honor my order. I am going to Florida until February so I will not know until then if he sent me the o-rings. I will follow-up then.

Pat:

When I read your earlier post about Dr Rebuild, I didn't think it sounded derogatory or bad. The going price for these NOS GM o-rings on other sites is about $12/each, if you can find them.............so I didn't think the Doc's current price was out of line. However, for what it's worth, when I purchased these o-rings in January 2010, they were $7.50 each. Not certain of the catalogue price.

I know I have ordered from Doc as well as other places that have both GM and (china) reproduction, and there is always a significant price/cost difference in the two. I choose, and get what I paid for. It's that simple.

I don't think that Doc should have gotten upset by your post, but that's just me. I wonder how he even knew about your post if he quit NCRS five years ago??

Larry

[Ara G.]

Re: Fuel Sending Unit Gasket

Thanks for the tip. I called Dr Rebuild today. They have the o-rings in their caralog for $3.50. I asked if they were real GM o-rings or aftermarket. She said they would call back after checking them. They called back and said they had real GM o-rings but the price was now $12.50. I ordered 2.

Pat. When I called yesterday they couldn't find them by part number and told me to order it online . I sent an hour on their website and couldn't find them . I just ordered them from Buick farm tanks to Larry's lead...