How to clean rusted thread bores?

jsmoke · 24 Dec 2020 at 11:51

Need a bit of a crash course. I have a couple of 13mm thread bores that have rusted inside the bore and hence new bolts will not go in, at least not without massive force which I dont want to do, wd40 or brake cleaner doesn't seem to be enough. So far I've briefly read up on thread chasers and taps but unsure which way to go.

I'm going to look for plastic or wire brush that will fit see if that works I need to get this sorted asap. Also I'm dubious about using a wire brush incase I flatten the threads.

How would you deal with this?

jsmoke · 24 Dec 2020 at 12:46

Finners said:
Yeah running a tap down the hole is the easiest solution.

What is it on? 13mm is an unusual size are you sure it's not Imperial?

Thought I'd ask as if you are just measuring with a ruler or similar it could be 1/2inch

Not 100% sure it's 13mm.

So do you just buy a tap the same size as your bore i.e in this case you'd buy a 13mm tap, and how are the taps able to move the rust/crud whereas the bolt can't?

jsmoke · 24 Dec 2020 at 13:12

tom_e said:
Yep same size/pitch as the current thread and because they're designed to cut into metal so they're more than hard enough to cut through the rust

So there are chaser taps and regular taps, I don't really want to risk cutting incase I mess it up, so I guess I'm looking for a chaser tap?

Also what about rust remover?

And what is this it's always on Google and seems to be able to handle multi thread pitches, why is one tool able to do that?

https://www.eurocarparts.com/search...Orhi1aabZYUYOgBihrYFVD6TPwhZHt84aAj5kEALw_wcB

jsmoke · 24 Dec 2020 at 14:29

Finners said:
That is for external threads so for repairing/cleaning up bolts. It's a thread file with multiple thread pitches.

You really need to narrow down the thread size and pitch and you can then buy a tap. If the hole is blind you will want a plug/3rd tap to run down it.

Traditional taps are either sold is sets or individually

Sets include 1st/2nd/3rd(Plug) taps and if tapping a new hole you use them in order to achieve a full thread in a hole. If like you, you just need to clean it up a 3rd(plug) tap will be fine or a 2nd at a push. Hopefully that hasn't made things even more confusing.

Yeah it has a bit, not sure what 'pluging a third tap' means. It looks like you have to buy a set as the individual costs are quite high and just as well buying set.

I really grudge having to do this and a lot of Toolstation products are crap.

What do you think of this, all I can find and I need the car tomorrow.?

https://www.toolstation.com/hilka-tap-die-set/p75650

jsmoke · 24 Dec 2020 at 15:26

rodenal said:
Thought it was a 13mm you needed though(as mentioned before pretty unusual)? That set only goes to M12, unless you meant a 13mm head?

It's M12 which is 12mm I believe, can you confirm that?

Edit: yeah just measured bolt with calipers it's 12mm so M12, so that set above has right size, also it's 1.5mm pitch.

Now the concern is getting the tap broken in the hole, which could happen with cheap tools.