63 gas guage sending unit locking cam question...

[Jim F.]

Howdy all! So I recently had a "reputable Corvette shop" install a new tank in my 63 Coupe. After driving it for a couple o' hundred miles, I noticed the tank dripping from several spots. Turns out the sending unit locking cam had come loose, which I learned the hard way when I touched it and it fell out dousing me in a quick fifteen gallons or so of premium all over my Sunday best. Wifey wasn't happy. Hmph..., anyway....Here's my question. I've never seen the locking cam in it's correct, "locked" position. How tight is the ring supposed to be? Are those little tabs on the locking cam supposed to lodge under the "notched" extensions on the tank receptacle or are the tabs on the locking cam just supposed to rest against the raised armatures of the receiving piece?

Might seem like a silly question, but as I said... I never actually saw the cam in it's fully locked position. Tried tightening it with a mallet and screw driver. That didn't work... So I ordered the installation tool for my next attempt. I'm sure that'll help, but I still want to know how far to turn the darn thing so it doesn't come loose again, or over-tighten it and screw it all up.

Sure would be nice to know how tight to make it so I can get it right. Thanks for any advice ASAP on this one PLEASE.

Jim "Stranded in Nashville" Femino

[Wayne P.]

Re: 63 gas guage sending unit locking cam question...

Jim what a story !!! When I replaced my sending unit I first made sure their was the proper gasket on the sending unit then I believe the locking cam was turned maybe half a turn till it was tight. I used a flat blade screw driver and a rubber hammer. I guess I should take a look at mine to make sure it hasn't loosened off.
Sounds like the reputable Corvette shop over looked tightening it. I would go back to them and let them know what happened.
This could have been a huge issue with the hot exhaust so near by. Glad to hear you are ok. What a mess.

[John H.]

Re: 63 gas guage sending unit locking cam question...

How tight is the ring supposed to be? Are those little tabs on the locking cam supposed to lodge under the "notched" extensions on the tank receptacle or are the tabs on the locking cam just supposed to rest against the raised armatures of the receiving piece?

Might seem like a silly question, but as I said... I never actually saw the cam in it's fully locked position. Tried tightening it with a mallet and screw driver. That didn't work... So I ordered the installation tool for my next attempt. I'm sure that'll help, but I still want to know how far to turn the darn thing so it doesn't come loose again, or over-tighten it and screw it all up.

Sure would be nice to know how tight to make it so I can get it right. Thanks for any advice ASAP on this one PLEASE.

Jim "Stranded in Nashville" Femino

Jim -

Photo below shows the correct final relationship between the (rusty) locking ring and the (shiny) receiving part welded to the tank; the upturned tangs on the locking ring are bottomed-out against the formations on the part welded to the tank. Note that the rubber O-ring goes between the sending unit flange and the tank, not between the locking ring and the sending unit flange. In the plant, we soaked the rubber O-rings in engine oil for several hours before installing them, as noted in the Assembly Manual.

When you click on the thumbnail below, you'll get a larger image; click again on that image and you'll get an even larger image.



TankConnectors (2).jpg

[Jim F.]

Re: 63 gas guage sending unit locking cam question...

Yea Wayne, I already let them know of my "displeasure". Thanks for the tips. I'm here by the grace of God to tell of it. Have a good one and thanks again.

[Jim F.]

Re: 63 gas guage sending unit locking cam question...

Thanks John! The pic helped enormously. And the tip about soaking the O-rings in oil seems to have done the trick on any leakage. Problem solved.

[Jim L.]

Re: 63 gas guage sending unit locking cam question...

In the plant, we soaked the rubber O-rings in engine oil for several hours before installing them, as noted in the Assembly Manual.

Interesting, John. I get the part about lubricating the o-rings.... done it for decades. But why several hours of soak time? Are the o-rings so porous they need time to absorb oil? Did they swell up after being in contact with the oil?

Expiring minds want to know....

Jim

[John H.]

Re: 63 gas guage sending unit locking cam question...

Interesting, John. I get the part about lubricating the o-rings.... done it for decades. But why several hours of soak time? Are the o-rings so porous they need time to absorb oil? Did they swell up after being in contact with the oil?

Expiring minds want to know....

Jim

Jim -

I dunno - Engineering said to soak them, so that's what we did, and I don't recall ever having an in-plant issue with them.

[Jim L.]

Re: 63 gas guage sending unit locking cam question...

Jim -

I dunno - Engineering said to soak them, so that's what we did, and I don't recall ever having an in-plant issue with them.

Works for me. Thanks, John.

[Rob M.]

Re: 63 gas guage sending unit locking cam question...

Jim -

I dunno - Engineering said to soak them, so that's what we did, and I don't recall ever having an in-plant issue with them.

Hi John,

Can't you write a book or something else which will stick in the future about your memories of factory car assembly procedures for us youngsters so all that priceless nitty-gritty information stored between your two ears will remain available for future generations.