[C2] Leaking sending unit
Thread Starter
Burning Brakes
Joined: Nov 2010
Posts: 1,236
Likes: 113
From: Oakland, Maine
Leaking sending unit
My 66 convertible has had a small fuel leak that seems to be from the O ring on the sending unit. I've just ordered the O ring. Because I'm without my garage and tools as my new place gets built I'll have my local mechanic fix my problem. My question is how tough is this going to be? Will he need to drop the spare tire cover? Any tips?
Race Director
Joined: Apr 2005
Posts: 11,273
Likes: 2,136
From: Bowling Green, Kentucky
A few tips:
1. Make certain it is from o-ring. Original and some reproduction sending units have adjustable packing for the two electrical posts as well. They can be tightened.
2. If the o-ring, buy NOS along with a NOS metal retaining ring. Check parts books for GM numbers and then search Ebay for new originals. I can find the numbers for you if need be...........just ask. Both are still available.
3. Tank must be emptied of gas. Easy to do with a 8 ft 3/8 x 1/2 inch syphon tubing and a few 5-gallon cans.
4. Use Vaseline on o-ring or soak in motor oil overnight.
5. Not certain if can be done with tub in place or not. My tub was out at the time since I replaced the gas tank at this time.
6. There is a cheap tool for removing and re-installing the sending unit retaining ring, although many just use a brass drift or similar to rotate it.
Larry
1. Make certain it is from o-ring. Original and some reproduction sending units have adjustable packing for the two electrical posts as well. They can be tightened.
2. If the o-ring, buy NOS along with a NOS metal retaining ring. Check parts books for GM numbers and then search Ebay for new originals. I can find the numbers for you if need be...........just ask. Both are still available.
3. Tank must be emptied of gas. Easy to do with a 8 ft 3/8 x 1/2 inch syphon tubing and a few 5-gallon cans.
4. Use Vaseline on o-ring or soak in motor oil overnight.
5. Not certain if can be done with tub in place or not. My tub was out at the time since I replaced the gas tank at this time.
6. There is a cheap tool for removing and re-installing the sending unit retaining ring, although many just use a brass drift or similar to rotate it.
Larry
Last edited by Powershift; Aug 21, 2019 at 11:38 AM.
Race Director
Joined: Apr 2005
Posts: 11,273
Likes: 2,136
From: Bowling Green, Kentucky
You made me get up and walk over to the garage........but here they are: 
o-ring: GM # 3825206
retaining ring: GM # 3774937
Original o-rings have the JR logo molded in on the small tab.
And just for you today: https://www.ebay.com/itm/74-75-chevy...AAAOSwCwxdWeDp This combination is same for Corvette as other GM cars during the 1960's period. You may find others you prefer better. This is just a random selection by me. So look around.
Larry
o-ring: GM # 3825206
retaining ring: GM # 3774937
Original o-rings have the JR logo molded in on the small tab.
And just for you today: https://www.ebay.com/itm/74-75-chevy...AAAOSwCwxdWeDp This combination is same for Corvette as other GM cars during the 1960's period. You may find others you prefer better. This is just a random selection by me. So look around.
Larry
