Otter LRC CM4647296 comes home

[Jordan Baker]

I finally got around to getting the fuel tank put back together, sealed inside and outside and painted. The end panels were welded in place. This took about 5 hours spread over two work periods. I had to use a copper flat bar as a backer due to the sheet metal being thin. In the end I’m quite happy with how the seams turned out. The outside was given a spray down with Purple Zep. I have been using it as a parts degreaser. The inside and outside of the tank was given an acid etch and then left to dry over night. I used a small blow dryer to circulate hot air. This worked great and ensured everything was dry. I then used 90% rubbing alcohol and gave one final washout. The hair dryer was setup again and the inside was quite clean, dry and rust free. The inside was then given a coat of ethanol safe fuel tank liner from the Hirsch product line. The added benefit is that it will seal up any and all seams and pinholes inside the tank.

[Jordan Baker]

The outside was given a spray of POR15 and then a topcoat of the green. Now the tank can sit for a few days for everything to harden up and off gas. Fuel lines, and sending units still need sorting out. But all in good time.

[Jordan Baker]

Fuel were lines made up from the tank to the junction in the floor. I used 1/4” copper nickel line. That stuff is so nice to work with and never rusty. I’m just waiting for some line clips to arrive so that I can secure the lines to the box. Lastly there is a lot of enjoyment when opening up sealed packages of NOS fuel tank caps. I had one original cap but it had suffered from the fire.

Still have to work out the fuel senders. I have both originals. However they were in rough shape with a lot of rust outside and inside. I’m also looking at getting modern ones custom made.

[David Dunlop]

Looking very good, Jordan!


David

[Jordan Baker]

Thanks David. In the end all this work will be pretty much hidden inside the hull and behind another plate. But I love a challenge…

Speaking of challenges, I decided to give it a go and rebuild the original fuel tank level senders. Considering the visible condition of what I had to start with where they were just as rusty on the inside as the outside and the mechanics were seized, I wasn’t sure if they would turn out.

I was able to clean them up using the citric acid bath. I was worried at first about the solution damaging the resistance strip, but thankfully there was no damage.

[Jordan Baker]

I used my multi meter to measure the résistance value of the unit. These units are 0ohms for empty and 30ohms for full.

Sadly the one unit had a broken contact inside. This was a small flat spring design that would move back and forth on the resistance strip. I’m still working out on how to make a new one.

[David Dunlop]

Jordan.

It might be possible that for any Sending Unit Assembly from GM Canada in the 30’s and 40’s, they all shared common electrical components and it was just the mechanical parts that varied to accommodate different tank capacities and dimensions. If so, you might be able to replace the broken part you have from another GMC Sending Unit of similar age and voltage and save yourself reinventing the part.

There might be some literature out there on the topic as well.

Nice the way those parts cleaned up by the way.



David