16 replies to this topic

[Joethemojomower]

HELP!! My Mini Engine depends on it!!

I went to change the oil on my recently purchased 1992 Mini HL.
But the drain plug seemed to be cross threaded (?) ..... as much as I turned it, it didn't unscrew.
So I gently tapped a screwdriver between the bolt and the sump casting while un-screwing the bolt. I managed to get the sump plug out, but the thread in the sump casting had disintergrated, a whole load of little bits of what looked like soft broken casting came out with it.

There is now only a tiny amount of thread left (about 2 threads, in a quarter segment) but no-where near enough to even hold the plug in place.

What can I do???

[john1.2pearl]

The only thing you can do is to Buy/use a helicoil kit like this Helicoil

[minisam1275]

your best bet would be to drill out the old thread and re-tap the hole only problem i can find with doing this other than getting to the hole with a drill and a tap is swarf getting into your engine or the drill going into something in the gearbox. if you did this you would have to get a different size sump plug and washer to match the size of the new tapped hole. the other thing you can do is to helicoil the hole but due to it being a sum plug i dont think this would work as it would leak.

hope this helps

Sam

[minisam1275]

well im not certain it would leak but personaly would not feel comfortable doing so

[mike.]

Minispares do a self tapping sump plug, more of a bodge really.

A properly installed helicoil repair won't leak, thats the best way of doing it.

[Joethemojomower]

i really dont want to drill it out and re-tap, for the reasons you said, (plus is £55) But having a look at the mini spares "SUMP PLUG WITH TAPER FOR GEARBOX REPAIR"
Its only a Tener, worth ago
Cheers Guys

[bluffin]

i really dont want to drill it out and re-tap, for the reasons you said, (plus is £55) But having a look at the mini spares "SUMP PLUG WITH TAPER FOR GEARBOX REPAIR"
Its only a Tener, worth ago
Cheers Guys

Hmm £10 and you could crack your gearbox housing and that will cost you more than £55 to put right, go for a helicoil

[matt615]

[/quote]
Hmm £10 and you could crack your gearbox housing and that will cost you more than £55 to put right, go for a helicoil
[/quote]


Agreed. I bought a Minispares sump plug repair plug once. However I was a bit alarmed to read in the instructions that there was a risk of cracking the gearbox casing if you weren't careful! So I never used it in the end.

[Joethemojomower]

Crack it? Blimey!
i shall have a good think about this one. maybe i should spend that £40 extra then

[duncancallum]

the taper ones are a bodge if you go easy and use it as a tap it shoulnt crack the box though

[taffy1967]

I had mine professionally heli-coiled last year by an engineering firm in Merthyr Tydfil.

They did a fantastic job and they even machined a new sump plug complete with the magnet and it looks almost identical to a standard plug.

The only worry I had was when I came to do an oil change a tiny bit of metal came out stuck to the magnet. But I was reassured by many here (after I'd posted a picture of that offending item), that it was only the heli-coil tang that should have been removed on fitting, but it obviously fell into the block.

Anyway the heli-coil is far stronger than the original thread and so far touch wood, It's not leaked a drop of oil.

[Blue Icarian Wings]

Got the same problem as you. I've spoken to 'The Mini Centre' in Preston the guy quoted me £40, to re-tap (not heli-coil) the hole/threads to the next size and fit a matching sump plug. Getting it done when I can next get it in.

[taffy1967]

A Heli-Coil is far stronger though and there are no threads to strip/fail. That's why their used on aeroplanes and stuff too.

[minisam1275]

ok i was wrong they dont leak

but they only use helicoils as repairs to damaged items so you dont have to re-tap or replace the damaged material

Sam

[Dan]

Actually lots of investment castings used in high spec and high value equipment use Heli-Coils and other forms of thread liner as original equipment, specifically because it almost entirely removes the possibility of torque damage to the valuable casting. If the thread liner is damaged it very rarely damages the outer thread in the casting, which would be almost impossible to repair in many castings and the liners can be replaced easily. Several parts in the cameras and other equipment I use at work come with thread liners installed in every single thread in the main castings. It is pretty poor engineering practice to use a very hard steel fastener in a soft alloy casting, the Heli-Coil is a far better solution.

Edited by Dan, 16 March 2009 - 02:48 PM.