How remove fuel sender - bolts are stuck

[P27]

How to remove the fuel sender (prior to repair)?
I've flooded them with WD40 for a week, and managed to slowly unscrew 3 of them, but the other 3 are refusing to turn!
I'm using a flat screwdriver blade, of the right thickness, but it's only 80% of the width of the round nut (as I don't have anything longer).
And however hard I press down when turning, I'm, tending to wreck the slot

Is there a better tool to use?
or is there a tool small enough to get in and cut the slot deeper?

roverFuelSenderA.jpg (30.47 KiB) Viewed 451 times

[SHyslop]

One of the problems of today are metric sized screwdriver blades in imperial size screw slots.
However, for it it's worth, here's how I've found these.
You get one good go at the screw heads but they may be past that point. A good tool to try is the biggest screwdriver blade in cheap 1/4" socket sets you'll find on eBay for about £8. If you use the T bar or ratchet handle with them, you can exert more downward and turning power than with a normal screwdriver.
If that doesn't work, there may be little to lose by using a mini die grinder and grinding off the screw heads.
This will let you get the sender out.
You will then be able to apply oil to the stump sticking out. Once it has done it's work, as much as possible, you can then attach a Mole grip ( a good one with good teeth) and hopefully extract the remains. If they don't come out they can be drilled with a tapping drill for
5/32" Whitworth, the same as original Meccano. Long screws in the part no 111 range (there are a few different lengths) can make a substitute for the originals.

[P27]

Thanks,

I'm at the car next week and will try again.


re your:
"can be drilled with a tapping drill for 5/32" Whitworth, the same as original Meccano. Long screws in the part no 111 range (there are a few different lengths) can make a substitute for the originals."

Now that's real info that can't be found elsewhere!!

[P27]

Oh just thought ... are the bolts brass or steel?

[SHyslop]

Which ones ? On the car or Meccano ? The Meccano ones are steel. By the way, the tapping size drill for 5/32" W is 3.2mm.

[luli]

The thread is 3BA. After removing the screws, use 3BA tap to clean the threads. I used stainless steel hexagonal screws when I returned the sender, so that next time removal be easier. Don't use a tool that creates sparks!

[lincsnick]

I've tried every releasing spray over the years and by far the best which seems to work where others fail is this, https://www.lubricantsuppliers.com/prod ... lldog-bdx/

It's expensive but worth it in my opinion. Soak it a few times over a couple of days. WD40 isn't designed as a releasing agent, it's a water displacer (hence the 'WD', the '40' was the 40th recipe tried) that has other uses but nowhere near as effective as something designed for the job.

The rust-converting primer from the same company is also excellent. Both were developed for industrial use.

Best of luck!