Petrol Tank - somewhat rusty/cruddy inside - quick fix ?

[hoogerbooger]

[Who the *ell invented imperial sizes !!! }

Julian S informs me:   Petrol tap thread is 3/8 BSP. 
[ I've found online something on BSP sizes that says the major diameter for a 3/8" BSP is 16.7mm & minor diameter 14.95mm - so it makes more sense now as when I the measure the diameter of the outlet hole in the tank it's more or less 5/8" (16 ish mm)

( except I currently have no idea what the  3/8"  refer to !!  cos a 3/8" )

Question 1: So is 3/8" BSP  defo right  for a 1965 B40 tank?

I need to blank off the threads to clean & seal the tank so looks like a plumbing blanking bolt like this will do ....hopefully ? 

https://www.flowfitonline.com/hydraulic-qrcs-and-adaptors/plugs-caps-and-crimp-nuts/bsp-solid-plug-38?gclid=Cj0KCQjwqYfWBRDPARIsABjQRYxY48leENdrKm5Pc6bBhvjA4XTCONUIRKtXTKA_ZZHKtsWVKsHqlncaAk-TEALw_wcB

Question 2:  Have been shaking around me nuts n bolts. Still some moving and shakin to do but I can see shiny metal appearing. Process is producing a flour of rust. I might be able to vacuum out a bit of this. Should the rest be washed out with a soapy water rinse ?

I have no airline so drying looks like it'll have to be a hair drier - which looks slow.

I'm going to use the POR15 kit ( degreaser/phosphoric acid metal prep/sealer) & looks like I'll still need to use paint stripper first to be sure any previous sealer is removed.

As far as I can see the only time I need to ensure the tank is fully dry is before the sealer goes on ?  Any advice ? or do I need to dry it out after other rinsings out of the tank ?

[ROYC]

Same subject going on here  https://www.a7a10.net/forum/index.php?topic=12801.msg101039;topicseen#msg101039

[AWJDThumper]

In answer to your questions:

Q1. It's much easier to use a rubber bung to seal the outlet from the tank.

Q2. The shaking will only remove loose rust - you still need to remove the film of rust using a suitable de-rusting solution. If you put sealant on top of rust, you will create an even bigger problem later on.

As said, it's best to de-rust first to see whether this produces shiny metal throughout. If you still end up with a rusty looking finish in places then there's probably a layer of sealant present which needs to be removed.

[Phil C]

From what you can see of my tank (see photo), would you say use the shaking method followed by a derusting agent, or just use a derusting agent, or do nothing for now?  It's not bad enough to need the shaking method, is it?   Phil.

[Greybeard]

It's difficult to tell from your photo, Phil, but the tank doesnt look that bad. At this time of year when theres a chance of improving weather (hopefully) I would be inclined just to rinse the tank out with fuel to remove any loose sediment and use it as it is.
Any rust will only get worse if its exposed to moisture. Keep the tank topped up with fresh petrol and possibly a dose of something like Millers VSP which is supposed to counter the effects of any ethanol and you may find that you never have to treat it.
I have a 1937 Sunbeam that has an unlined/untreated tank and its fine.

Hoogerbooger, BSP thread sizes refer to the bore of the pipe, not the outside diameter of the thread. A 1/4 BSP is about 3/8 diameter, a 3/8 is over 1/2 inch  Have a look at the Draganfly website. They have a useful section that explains it. Imperial threads do make life interesting don't they? Metric threads also have their quirks though. I recently made up some long engine studs for a mates 's Yamaha FJ1300. M10 but 1.25mm pitch instead of the usual 1.5mm. I had to cut those on my imperial lathe which is always a challenge 

Steve (wots wondering whether Spring has arrived yet)

[Phil C]

Thanks, Greybeard.   Hoogerbooger, A Zeus book is a useful thing to have for info on threads etc (although there are occasional odd ones such as Greybeard describes which won't be in there.) Years ago when I worked in machine shops we always carried one.  Phil.

[Phil C]

A bit disappointing though that Zeus books don't include British Cycle threads.   Phil.

[AWJDThumper]

From what you can see of my tank (see photo), would you say use the shaking method followed by a derusting agent, or just use a derusting agent, or do nothing for now?  It's not bad enough to need the shaking method, is it?   Phil.

The patch shown isn't much to worry about. However, what does the bottom of the tank look like inside on either side and what does the roof of the inside of the tank look like because that can go rusty because its not usually covered in petrol?