Quanta Tank - Leaking Sending Unit Direction

[Barry J.]

I have a 66 with a new Quanta Tank and the after market sending unit. Current the o-ring is leaking and I have read several threads that only GM O-rings seal correctly. Given I plan to have the car judged soon and I need to get this leak stopped. Any recommendations on sending unit and o-ring? Should I go with Quanta sending unit to ensure the best fit possible? Thanks

[Ray G.]

Re: Quanta Tank - Leaking Sending Unit Direction

Hello;
You can do this in the car. Have plenty of ventilation. Siphon most of the gas from the tank. Jack up the car on the Passenger side frame rail, under the door, as far back as possible without hitting the RR tire. This moves whatever gas is in the tank to the driver side.
After removing the tire carrier. Remove the sending unit. Fit the sending unit back into the tank without the Oring to make sure nothing is obstructing the flush fit in the tank. Occasionally the fit will be obstructed by poor alignment of the pick up screen or tube.
Check for any damage to the Oring, if necessary replace. Coat the Oring with bar soap softened with water or saliva. Reassemble using care not to damage the Oring.
The soap does two things. It make turning the lock ring easier and also acts as a sealer. Soap dissolves in water but not in gas.
I've been told liquid soap does NOT work as it dries slower.
Allow this assembly to dry for 8 hours before exposing to gasoline.
Hope this helps.
Ray

[Mike M.]

Re: Quanta Tank - Leaking Sending Unit Direction

i've always coated the o-ring with silicone dielectric paste and had no problems. as ray says, the o-ring must be lubricated. mike

[Bill C.]

Re: Quanta Tank - Leaking Sending Unit Direction

Barry
I just had this problem on my 63.
I replaced the O-ring and it still leaked.
I contacted Mike Ernst(on this board) and he had nos seals.
When I compard it with the others I had, I could see it was thicker.
I soaked it in oil and installed and it fixed the leak. I suggest you contact Mike; as he may still have some seals.
Good luck
Bill

[Barry J.]

Re: Quanta Tank - Leaking Sending Unit Direction

Thanks for the information! I have the car up on the passenger side and that worked great however after replacing again with a new spectra o-ring it stil leaks more than ever. Bill, do you have a phone number for Mike Ernst? Mike McCagh, where di you get the silicone dielectric paste, I have soaked in motor oil the last two O-rings. Thanks Barry

[Mike M.]

Re: Quanta Tank - Leaking Sending Unit Direction

i get ac deco dielectric silicone past from deco dealer. think i have a couple of o-rings that came with genuine deco sending units. send your snail mail address and i'll send you one,on the cuff , if my memory of extras serves me. mike

[Terry M.]

Re: Quanta Tank - Leaking Sending Unit Direction

Thanks for the information! I have the car up on the passenger side and that worked great however after replacing again with a new spectra o-ring it stil leaks more than ever. Bill, do you have a phone number for Mike Ernst? Mike McCagh, where di you get the silicone dielectric paste, I have soaked in motor oil the last two O-rings. Thanks Barry

Barry,

Take your choice:

http://www.amazon.com/s/?ie=UTF8&keywords=dielectric+silicone+grease&tag=googhydr-20&index=aps&hvadid=44724301065&hvpos=1o1&hvexid=&hvnetw=g&hvrand=15314564855995933215&hvpone=&hvptwo=&hvqmt=b&hvdev=c&ref=pd_sl_6co88du4ss_b#

20 pages worth.

[Roger P.]

Re: Quanta Tank - Leaking Sending Unit Direction

Hi Barry, I think my post from a thread not long ago will help you: "I replaced my leaking sending unit and O-ring back in December with a Fargo unit which was determined to be the best repro unit available. I don't think they make the Fargo unit any longer as it was nearly impossible for me to find one. I researched the repro sending units with all of the typical vendors and no one had a Fargo unit. They all had press-in type electrical connectors and the units visually looked cheap. I then remembered a smaller supplier located on the west coast of Florida near Tampa called Davies Corvettes. They had a few Fargo units in their inventory, so I very happily purchased one. The Fargo unit has electrical connectors that are attached with nuts so they can be tightened in the future if necessary. The unit itself looks very similar to the original sending unit and appears to be well-made. Before installing the unit, I soaked the O-ring in motor oil as suggested, but it didn't tighten properly on my tank. After inspecting the new O-ring and the old one (which was only about 5 years old), I could see that the new one was visually thinner. Not having another option, and since the old sending unit was leaking and not the O-ring, I decided to recycle the 5 year old O-ring. Everything was fine for a few weeks... until I noticed a gas leak on my driveway. Son of a gun, the darn O-ring was leaking! So I called Davies Corvettes and had them send me a new O-ring from their inventory; not an O-ring from another Fargo unit, but rather a $ 3.00 replacement O-ring. I also ordered a replacement O-ring from another vendor. The O-ring from the other vendor was thinner than the 5 year old leaking O-ring (much like the one that came with the Fargo unit), but the replacement O-ring from Davies was thicker. I then contacted Ara since I knew that he had an NOS O-ring so I could find out the thickness of the NOS O-ring. He sent me a photo showing it was exactly 3 nickels thick (which equates to 6mm +/-) and that was the exact thickness of the O-ring that I purchased from Davies. Halleluiah!! Thank you again, Ara!! My brother has an auto repair shop, so I had his mechanic replace the O-ring for me again (after soaking it in motor oil overnight). To make sure that it tightened really well, he "love-tapped" the 3 tabs on the fuel tank so the locking cam would tighten a tad more. I think that was a very good idea and is the "magic trick" for this task. It's been a few weeks since we replaced the O-ring and so far, so good... not even a hint of fuel. So I would suggest that you contact Davies Corvettes and order a replacement O-ring once they confirm that it is 3 nickels thick. If you need a fuel sending unit, and assuming that you don't have an original that can be restored, I would suggest getting a Fargo unit from them while they last. I certainly hope that I don't have to deal with this again for many, many years!!" Good luck, Roger (50141)

[Bill C.]

Re: Quanta Tank - Leaking Sending Unit Direction

Barry
Sorry,I have no tel. number. The NOS seal is the way to go.
Good Luck
Bill

[Terry M.]

Re: Quanta Tank - Leaking Sending Unit Direction

Thanks for the information! I have the car up on the passenger side and that worked great however after replacing again with a new spectra o-ring it stil leaks more than ever. Bill, do you have a phone number for Mike Ernst? Mike McCagh, where di you get the silicone dielectric paste, I have soaked in motor oil the last two O-rings. Thanks Barry

In a moment you will have email.

[Ara G.]

Re: Quanta Tank - Leaking Sending Unit Direction

I had this problem too. Search the archives for my thread. Not only is the O ring a possible source of the problem, but the locking cam can also be too. I would use an original locking cam if you have one. The ears and tabs on the repro units do not allow enough of a bite. If you need/want the "special" tool to install/remove the locking cam you are welcome to borrow it (anyone is actually, just email me....it belongs to a buddy of mine who logs on here frequently so I can't wait for the ribbing to start) Soaking in motor oil overnight is also key. Good luck. ARA

[Mike M.]

Re: Quanta Tank - Leaking Sending Unit Direction

opriginal o-rings are 6.09mm thick. mike

[Jim S.]

Re: Quanta Tank - Leaking Sending Unit Direction

The locking cam is still available . GM Part # 3774937

Jim

[Barry J.]

Re: Quanta Tank - Leaking Sending Unit Direction

Does anyone have the GM sending unit Part Number?

[Joe R.]

Re: Quanta Tank - Leaking Sending Unit Direction

Barry,

Original part number of the AC Tank Unit was 6428065. I also have one that is the exact copy that has a tag on it that says "Service Sender" PN 6425827

JR