I am preparing to drop my gas tank in order to change my fuel sending unit and lines, and looking for advice from folks who have done the same. I am hoping to get my fuel gauge working again (all tests point to the gauge and wiring being good).


Specific things I'm curious about:
Are there any parts you would recommend changing at the same time? (pad above tank? straps? mounting hardware? tank itself?)

Is any portion of the line from the tank to the pump metal? I have only seen rubber so far.

Any products/specific ways you would recommend to clean the tank if i reuse it?

Any value to using a sending unit from a specialty parts dealer? (i.e. fusick, opgi, etc.) Doorman sells one as well for about half the price, and from past experience its probably the same part re-boxed anyway!


Thanks in advance, any info/pointers would be very helpful!

 

Dropped the tank on my 71. Empty the tank as much as possible, to make the tank as light as possible. I had to replace the bolts because I had to cut them to get them off. Replace the rubber lines also. It is a good MAW. As for the rest check out the tank when you get it out. I had visions of having to replace all these things but in reality everything was fine.
I dropped mine to replace the rubber fuel lines, that were leaking. I can't help on sending units.

 

Grab a pad from 70Post, well worth it.

https://classicoldsmobile.com/forums...on-item-4.html

 

I would replace the sock on the fuel pickup which is part of the sending unit. A new sending unit may come with one.

 

Use plenty of penetrant on the on the threads for the straps before starting. Replace the rubber fuel lines in between the tank and the hard lines mounted to the frame, I use fuel injection hose.

 

The entire fuel line that runs along the frame rail is metal. There are only short sections of rubber hose from the tank sender to this hard line and from the hard line to the fuel pump at the engine.

Look for a build sheet on top of the tank when you drop it. Don't be surprised if you don't find one, but you might.

One way I've found to empty the tank is to disconnect the rubber line at the fuel pump and route it into a gas can. Now use a blow gun and air compressor to pressurize the tank from the filler neck. Use a rag to seal the hole. This should blow most of the fuel out of the tank.

 

Love that idea

 

Laziness is the REAL mother of invention...

 

You didnt say what year your car is but if your car has the "vent valve", that also needs to replaced. There's a small foam filter inside the valve that dissolves because of age. You can replace just the valve or replace the valve with the 2 hoses (it comes with clamps). Fusick, OPGI, Year One (just to name a few) should have it.

 

Thanks for all the info, good insight. I'm going to attempt this next weekend, hoping I can get all the way through this one without stopping to order parts!

Will do, looks like a good product.

Seems like a long shot, but here's hoping!

Definitely going to give this a shot.

Car is a '68. How/Where does this mount exactly? On the vent tubes on the top, passenger side of the tank? Just 2 hoses and a clamp there now if thats it.

 

Did Oldsmobile have a gas tank vent valve in 1968? If it used a vented gas cap I would suspect not.

 

Its mount towards the passenger side front of the tank. There's 2 nipples on the tank where the vent hoses clamps onto.

 

Went through the CSM and it seems olds did use a vented tank in '68, but with 2 hoses only, no valve, but it seems like an upgrade so I may grab one.

The more I look at my old steel lines, the more I feel like I ought to change them as well as the rubber portions, they already look like they have been patched once by the tank. Has anyone managed to do this with the body on the frame?

I did the front to rear brake line a while back and it was neither fun nor easy but I got it done eventually. It seems like theres even less clearance on the the fuel line side though.

 

Use a kit like this to thoroughly clean and seal the inside of the tank when you drop it:

https://www.summitracing.com/parts/s...56-3/overview/

You can also paint the outside of the tank with a durable paint like POR 15 or Rustoleum.

 

I use this to coat the inside on both of my Cutlasses gas tanks.
http://www.eastwood.com/gas-tank-sea...nk-sealer.html

And use this paint my gas tanks
http://www.eastwood.com/ew-tank-tone...sol-13-oz.html

 

The products Ely linked are a great option too. All of the fuel tank restoration kits are pretty much the same so get whichever is cheapest. Also, make sure you wear a respirator. NOT A DUST MASK! This stuff is poison so make sure you wear proper PPE.

 

Thanks for the heads up!

So what did you do with the toxic mess once you used it?

 

I was able to dispose of the toxic mess at a community "clean up day." The bad part is that it had to sit in my garage for months to wait for the "clean up day."

You can also ask your community if they have a recycling center where you can get rid of it.