Hack Job Sending Unit

[Slickcraft235]

Greetings all,
Somebody did a real hack job on mounting a sending unit on an aluminum gas tank on my boat. I'll try to post a picture, but for now let me describe.
The gas tank hole is 2" in diameter.
The sending unit 5 bolt pattern is not wide enough for all 5 screws to engage the tank metal. Their solution was to just tap and sink 3 out of the 5 screws, caulk like crazy, and hope for the best. We'll that wasn't such a hot idea.
Any ideas how I should remedy this? I'd would like to keep the sending unit if possible.
Thanks in advance,
Chris

 

[alldodge]

Take a 1/8 inch flat plate (or thicker) at least 1/2 inch larger then hole needed for sender. Drill hole size needed for sender. Use cork or other gasket which gas does not have an issue with. Fasten plate to tank then sender to plate

 

[Slickcraft235]

Thanks alldodge,
That's what I was thinking too. Any chance I could go BOOM while drilling?

 

[alldodge]

Thanks alldodge,
That's what I was thinking too. Any chance I could go BOOM while drilling?

Sure, I'll watch for the news at 11
Assuming this is aluminum tank and not steel. I'm old so manual drill is something I have

Move away from tank
Drill hole in plate
Drill 5 holes for sending unit and tap holes
Drill 3 to 5 thru holes in plate. Thru holes are large enough to clear threads or screws that will be used to bolt plate.
Install sending unit

Get a fan and have it blow air in area of tank
Best to use air drill or hand drill. If a Battery drill is used, then lots of air flow from fan or fans

Place plate and sending unit
Drill holes sized for taping screw size
Tap holes

https://www.amazon.com/Frylr-Speedy-Powerful-Manual-1-5MM-10MM/dp/B078SQTLMM

 

[Slickcraft235]

Thanks for the step by steps.
Tank is aluminum.
I think I'll use 3/16" for more bite
Should the plate aluminum too?
What metal should the screws be made of?
Looks like 10/32 is a standard thread for this application ?

 

[ScottinAZ]

Thanks for the step by steps.
Tank is aluminum.
I think I'll use 3/16" for more bite
Should the plate aluminum too?
What metal should the screws be made of?
Looks like 10/32 is a standard thread for this application ?

I would do the plate out of aluminum as well as the tank. less chance of getting corrosion under it that would NEVER be checked. If you cant do aluminum, I would go with stainless, but thats more of a pain to work with if you dont have good tools. Stainless will eat the tips right off your drills if you dont use good ones at the right speed, the chromium in it that makes it stainless, also makes it TOUGH stuff. My sender has standard 10-24 stainless self tapping screws, but 10-32 will work just as well if you tap the base first.

 

[Bt Doctur]

I simply slightly rotate the sender to a new location, hand drill for 10-32 and retap

 

[ScottinAZ]

I simply slightly rotate the sender to a new location, hand drill for 10-32 and retap

if it was just stripped mounting holes, I would agree with you. Problem is, from his initial pic, the center hole was drilled too big for the mounting screws to get a good bite. whomever did it originally buggered it up good.

 

[alldodge]

BT doctur has you on the right track. So long as soft and non ferrous metals are used there will not be an issue

 

[Slickcraft235]

BT doctur has you on the right track. So long as soft and non ferrous metals are used there will not be an issue

To plate or not to plate - is that now the question ? IOW, just rotate, retap, and bolt her down?
Check out the pic - can I get away with that? Looks like all my new bolt holes would be very close to the edge of the 2" sender hole if I tried this. Would I get enough "bite" being so close to the edge? Is this where the metals being non ferrous come to my aid?

 

[Bt Doctur]

If there is fuel in there now pump it into containers ,etc. Then fill with water to almost the top. Fuel will be on top. syphon it off, fill to the top with water and drill away..
Pump the water out let dry using shop vac on"blow"

 

[jimmbo]

Thanks alldodge,
That's what I was thinking too. Any chance I could go BOOM while drilling?

Very Good chance indeed, every Drill I have ever used, had plenty of Sparks happening inside it.

 

[Slickcraft235]

Very Good chance indeed, every Drill I have ever used, had plenty of Sparks happening inside it.

Trying to avoid this by using a hand drill

 

[achris]

That plate/tank is too thin to get enough threads on, use Riv-Nuts.

 

[nola mike]

Very Good chance indeed, every Drill I have ever used, had plenty of Sparks happening inside it.

Wonder how much of a risk a brushless drill is

 

[alldodge]

Manual drill not electric
Drilling non-ferrous material

 

[Slickcraft235]

Please advise on best way to drill and tap 1/4" aluminum with just a hand drill. Never done this before and want to increase my chances for success.

 

[alldodge]

Center punch then might take the most turns but far less chance for heat to build up with a brace bit drill



Use a shop vac outside the boat and just the hose blowing not sucking, by the bit to help from keeping fumes from building.

I do like Chris idea of using rivets. Only issue is if gaskets leaks the need to drill rivets and they have a steel pin

BT has the safest idea with drain and fill with water

Might even

 

[alldodge]

Another idea, get everything good and clean the JB weld it on. Again it will be a real pain if it ever did leak or had another problem

 

[Slickcraft235]

Hey guys I'm back!
Since my tank was so hacked up I decided to order a 1/4" x 4" diameter aluminum disk. I will drill out a center hole for the sending unit shaft, then gasket and 10-32 bolt down the 4" disk to the tank, and then use it as a base to bolt on the sending unit. A couple of questions . . .

1. I plan on using 1/8" appropriate rubber-type (not cork) gaskets. The sending unit uses the typical 5 bolt pattern. How many 10-32 bolts will I need to a fix the perimeter of the 4" disk to the tank seeing that it is larger. 5,6, 8?

2. Should any type of gasket sealer be used in conjunction with the rubber gaskets?

3. What is your preferred method of sealing the heads of the bolts? O rings, gasket sealer, nylon gaskets ?

Please advise, I really don't want to screw this up!

CT