Gas tank sending unit

[Business_As_Usual]

Replacing gas tank sending unit on 40’ business coupe.  Is there any advice out there on removing the gas tank?  Do I have to remove the left rear fender to provide room for the filler neck?  Do I need to put a sealant on the sending units gasket?  Any and all advice is appreciated.  Thanks to all, Tom

[buick looks fine for 39]

Removing the gas tank is pretty straight forward. It is not necessary to remove the fender but remove as much gas as possible to lighten it. As a safety device it's not a bad idea to use a florescent drop light to lessen the chance of fire. A padded floor jack under the tank makes the job much more controllable and easier. I didn't bother applying sealant to the sending unit gasket.

 

Whatever you do don't place yourself directly under the tank and drop it on your face as I once did. It does prevent the tank from getting scratched but It's bad on tooth enamel.

 

                                                                                              Thanks

                                                                                               Leif

[neil morse]

I dropped the tank on my '41 and agree with everything Leif says.  I emptied the tank as completely as I could before the job.  (The drain plug was frozen in place, so I had to use a hand pump to get the gas out -- a little messy, but it worked pretty well.)  I just used a floor jack with a wooden board to support the tank, and it came down very easily.  I don't know specifically about the '40 coupe, but on my '41 sedan the filler pipe just dropped down without any problem.  I also did not use any sealant on the sending unit gasket.  However, I did install a dedicated grounding wire, which I highly recommend.  In case it's helpful, you can see what I did here (click on the arrow in the upper right hand corner to get to the right post):

 

 

 

[Morgan Wright]

The float in the sending unit is a cork. It will be all dried out and corroded. Don't bother trying to fix the cork, just get a bottle of wine, the cork is exactly the same size. In fact, there is no part number for all these corks, they are just wine bottle corks. 

[Business_As_Usual]

I was going to put the rear of the car on jack stands to allow room to clear the fill neck from the bumper. Is raising the car necessary?  I think the dedicated ground wire is an excellent idea. I’m thinking the old sending unit is original. My new one does not have a filter sock on the gas line. I’ve read where some people remove them anyways. Back in 1940, I don’t think they had the sock type fuel filter on the gas line, but I don’t really know.  Tom

[Matt Harwood]

Everybody said putting in a new fuel sending unit would be easy and quick and that it would make my fuel gauge work. Instead it took six weeks and cost $1200 and I still don't have a working fuel gauge:

 

 

My advice? Leave it alone. Experience has taught me a harsh lesson here.

[Gary W]

Here's my step-by-step from my '37 Buick.  maybe it'll help you with the steps involved:

 

 

[neil morse]

3 hours ago, Business_As_Usual said:

I was going to put the rear of the car on jack stands to allow room to clear the fill neck from the bumper. Is raising the car necessary?  I think the dedicated ground wire is an excellent idea. I’m thinking the old sending unit is original. My new one does not have a filter sock on the gas line. I’ve read where some people remove them anyways. Back in 1940, I don’t think they had the sock type fuel filter on the gas line, but I don’t really know.  Tom

I found it very helpful to have the car body raised up on jack stands to give you more room under the tank.  You can see what I did from the pics in my thread.  I used a "sock" just because the unit I bought from Bob's Automobilia came with one.  If your tank is clean, you probably don't need to worry about it.  Speaking of which, you can see from my thread that I had the tank sand blasted and coated as long as I had it out of the car.  I would recommend that you take a look inside once you take the old sending unit out.  (A smart phone camera with a flash will do a great job of showing you the condition of the inside of the tank.)

[Morgan Wright]

In my '40 it was just 2 metal bands that held the tank up under the trunk. Once you get the tank out, the sending unit was a rheostat attached to a float arm with a cork on the end. You can check the rheostat with a multi-tester by hooking one wire to the wire and one to ground, and set the tester on ohms. When you move the float arm up and down, the ohm meter should go from 0 to infinity and back. I was lucky, mine worked. It just needed a new cork.

[Century Eight]

All of the comments here that i see are good  except one that is missing is that you might want to invest a whole three dollar bill on re-installing the sending unit with the stainless steel screws that are offered by Bob’s or CARS and others in their catalogs.  It makes it easy repeat the procedure if you ever have to do it over again (ask me how I know).  Sometimes the cork gets gas soaked again or the metal float also offered can get a hole in it, fill up with gas and sink to the bottom, and then you get to do it all over again.

 

The whole repair is not hard, although I would also add an extra ground wire.  There is room to wiggle the EMPTY tank out from under the car and the hardest part is trying to get back up off the floor when you are seventy three years old.  I’ve become fairly accomplished at it and somehow it seems to have become part of my workout routine.

[Str8-8-Dave]

10 minutes ago, Century Eight said:

the hardest part is trying to get back up off the floor when you are seventy three years old.

Ahh- at least you are still getting back up off the floor Phil- I'm 72 so I share your pain.  I'm also facing the possibility or having to remove the fuel tank on my 1931 8-66S to replace the hydrostatic fuel sending unit, a component of the King Seeley Tele-Gage fuel gauge setup.  

 

Dave...

[Buick35]

On my 35 40series sedan I made a small access hole above the sending unit on my wood trunk floor.I then covered it with an additional piece of removable plywood.Easier than removing the tank for future repair.