FH - small repairs

 Spring is here and I'm away using the Square Four for some little house renovation jobs in a nearby town. There's a little bit of time in the workshop to do a few bits on the Huntmaster. 

We'll start with blocking that hole in the primary case that used to be used for the chain oiler before the fully Enclosed Rear Chain Case arrived. It's lost its blanking plug so I've made a new one up from a cheese head 3/16" BSW screw with a fibre washer:

The next one is a bit more serious. This is the pinhole in the fuel tank - I've taken the tank off for better access which is quite easy with these single centre bolt tanks. I've opened the hole up a little bit to clear the paint with a scriber and I've cleaned the area with acetone.

I've put a blob of Seal-All in that hole - just a tiny blob. After deliberating for a while over the approach I would take to this repair I realised that Seal-All had been sealing several holes in the W/NG tank for many years, and is still good. We'll see how this turns out tomorrow.

Fixing the leaky tank

So, I have had the little camera inside the tank to look at the mount damage. This is the front, where the leak is; this is the better of the two:

This one appears to show the worst leak:

This is the tap connection from the inside:

These next pictures are the two rear mounts, which don't leak:

Curious tank sealer.

So you may remember that I qualified the use of the 'Seal-All' in this application in the blog post 'Leak Test'. To effect a repair, we will start by using a small wire brush in the Dremel to clean the area to be sealed.

In goes the sealer. you can see it land from the gap beside the mounting plate - I pushed it into place with a chopstick!

So I have replaced the offending tank bolts to avoid the threads become contaiminated with sealer. We will leave it for a few days to set.

Leak Test

As I may have mentioned I have a leak in the fuel tank. I found a product online called 'Seal-All' which purports to be suitable for leaky tanks and is 'gasoline proof'.

I thought I would devise a little qualification test. These are the bits we will use - ignore the regulator! The plan is to make a hole in one of the tins, seal it, and then subject it to long term immersion in fuel to determine if it leaks, or if the sealant changes.

I made a suitable hole in one of the tins using an 8 mm wad punch, which should be very similar to the hole in my tank which was cut with an over long M8 bolt. The idea is that the area of adhesive exposed to the fuel will be comparable to the real hole in the tank:

I laid the adhesive over the hole and let it cure in this position for 24 hours:

After the cure, it is still soft, like a hard cheese. 

So this is the test setup. I have fuel in the top tin, covered with a polythene bag. This is sealed to the tin with a tight elastic band, but the bag is loose to allow movement of the bag to compensate for volume changes in the air above the fuel, preventing any pressure developing in the can which would change the test conditions; the bottom can is there to catch the drips coming through the sealant from the top can:

We'll leave it for a month and see what happens, investigating periodically so that we can get a reasonable idea of how long it lasts - I don't want to look for the first time at 30 days to find a leak which may have happened after 2 days! For the record, the test started on Wednesday 31st August 2016.

Here is the first inspection, 5 days in:

Still no leaks. The sealant is a little harder - maybe a 24 hour cure is not long enough?

Second inspection, two weeks in; still no leaks:

Its possibly a little harder - I'm starting to consider where this will handle any vibration?

Latest picture. 21st September, three weeks in. No change:

More than four weeks, still no change:

6th October - five weeks:

Still no change on the 12th October - that's six weeks:

October 2024 - this repair still hasn't leaked!