Drilling into a aluminum fuel tank

[Monte Cresto]

The grease thing sounds ok (I've used it in other drilling operations) however, be careful
of using a sending unit in the tank. I have a friend with a Valiant 40 with aluminum tanks
that had the seams of the tank eaten away with the electrical current and was a major
operation removal and repair (we both use a stick to measure fuel now)!

[wandering rober]

Keep the stick ,it will never fail ya !

[model 10]

Originally Posted by wandering rober

Keep the stick ,it will never fail ya !

I have been flying since 1973. With my planes it has always been the stick and a clock. It works just about as well on the boat.

[sailah]

I had to holesaw into my aluminum fuel tank to install a in-tank pickup for my fuel polisher. I knew I was going to get chips in the tank but the fuel polisher got them in the first filter immediately.

You could always drill and let everything settle. Use a thin tube and turkey baster to feel around in the bottom and suck them up. Or buy an inexpensive 12v pump (Carter P4070), plumb through your racor and do a "polish". Copper refridgeration tubing works well for making an inlet tube wand.

But your Racor will surely get the chips well before they ever get to engine even if you leave them

[a64pilot]

Just do not use copper to stay in the tank, apparently it will cause dissimilar metals corrosion.
I know your not abdicating keeping it in, but I made a pickup tube out of a piece of copper pipe and then learned better on this forum and got it out before it caused any issues

[sailah]

Originally Posted by a64pilot

Just do not use copper to stay in the tank, apparently it will cause dissimilar metals corrosion.
I know your not abdicating keeping it in, but I made a pickup tube out of a piece of copper pipe and then learned better on this forum and got it out before it caused any issues

Hmm, I did not know this. I do have a copper pickup tube for my fuel polisher which is then connected by a brass compression fitting to the aluminum tank bung. Looking at galvanic scales it does appear that they would be an issue.

I'm trying to fight the cobwebs and remember back to high school chemistry. That would require an electrolyte to create a reaction correct? So my question is: Is diesel fuel an electrolyte?

Because the aluminum tank is so large compared to the copper tube, I would think the effects would be negligible. I used rtv sealant between bung and tank but it is connected by SS bolts.

[pwilletts]

I have the stick on style level indicators,,,but hey don't seem to work

[Dougtiff]

O.K. First off it would be better to be able to access the inside of the tank for inspection and cleaning, aluminum diesel tanks have a history of corroding over time, usually at the lowest point, i.e. a corner, where all the welding comes together [i know from experience], so it would be prudent to install a inspection hatch with the sender penetrating said hatch, there is a company [seabuilt] that makes a bullet proof access plate system in aluminum and stainless steel, comes in 6,8,10,14" dia. has a fold back ring that is inserted after cutting the hole, very simple to do, i added these for my tank's, which i inherited when i purchased this boat, installed on fuel, water and holding tank's, good luck.

[a64pilot]

I'm not sure how or what it takes to have dissimilar metals corrosion, just that it can be a problem, Pure Diesel fuel would not be an electrolyte I don't think, however all Diesel has some water dissolved in the fuel, enough to be a problem? I don't know
West Marine sells a plastic dip tube that has an aluminum threaded end, so of course then it's aluminum against aluminum, and plastic, so I went that way