12 replies to this topic

[tone_vvc]

Hi.
I'm in the process of rebuilding my Mini City E having bought a recon gearbox. The Sump plug hole has been helicoiled, but this has disintegrated upon removal of the plug, as has the 1st mm of the hole wall. The furthest 2 rings of the helicoil (into the gearbox) are still in situ.
So I have bought a tapered plug from Minispares and tonight installed it with a rubber washer, put a drop of oil in it to flush out any metal fragments and left til morning to remove.
Question
Minispares say you dont need a washer, but it will be metal on metal which i'm not sure about.
If I do use a washer, what are the pros and cons of using nylon (plastic), rubber or copper??
This is my 1st time at engine rebuild so all help gratefully appreciated. I have read other posts but I cant see my dilemma in others.
Thanks in advance.
Tone

[samsfern]

Id use a copper washer.

[bmcecosse]

I would return the gearbox for a refund - I would never trust that to hold.....

[Ethel]

A Taper plug should wedge itself in & seal on the threads; a washer may have it pulling on already weak threads. Ptfe tape would be a better option, but tend to agree about getting a replacement or proper fix.

[jaydee]

A Taper plug should wedge itself in & seal on the threads; a washer may have it pulling on already weak threads. Ptfe tape would be a better option, but tend to agree about getting a replacement or proper fix.

+1

Dont put washer on taper plugs.

And give a call to the builder first, helicol kits are usually strong...

[tone_vvc]

Thanks for all the comments guys.
No excuse but being a 1st timer i think i might have rushed into getting the gearbox, as builder is uncontactable.
So think im stuck with making a proper fix?

[The Principal]

if your stuck with it get it down the local machine shop and get a new helicoil fitted

[MiniLuke]

Are you confident the 'box is reconditioned to a good standard? If the sump plug thread is bad I'd be concerned the box hadn't been properly rebuilt either.

[tone_vvc]

I know what you mean, but yes i am confident the gearbox components,etc are new.

[mininuts]

Drill out and re-thread bigger to suit a sump plug from another vehicle?

Did this to our VW camper, it's now got a Renault sump plug

[dklawson]

As above, if this is a gearbox rebuild you paid for, have it repaired or replaced properly by whoever did the work. There is no need or reason for you to accept this.

If this is a used engine/gearbox you bought that someone else paid for your options are much more limited.

IF you fit a tapered thread drain plug, use the PTFE tape mentioned above. However, I'll bet such a tapered plug does not have a magnet like the original drain plug so I would consider this a temporary thing. I have used pipe plugs for drain plugs in non-Minis without issue. However, I chose to use Nylon plugs so they would not put stress on the tapped hole in the sump. Still... you are not going to have the magnet on the drain plug.

Fitting a larger size drain plug is possible but... how much bigger? The original sump plug was 5/8 UNC. Once HeliCoiled, the tap would have been drilled out larger... then when those threads fail.. bigger still. Your drain opening where the HeliCoil and casting have failed is likely to be close to 11/16" now. That means your next sizes up will be about 18mm or 3/4"/19mm. Those are some REALLY big sizes.

For future reference I no longer use the copper sealing washer on my Mini's drain plug. There have been too many horror stories on stripped sumps and I have installed HeliCoil's on the sumps of friends' Minis to fix the problem. Now I use a bonded metal/rubber seal. These are the type of seals used on some European cars and similar to the sealing washers used on hydraulic fittings (G3/8 size). The rubber gets crushed in the gap but the metal portion prevents it from moving out of place. You get an excellent seal with low torque.

If you have no alternative than to use the existing gearbox with its damaged drain and only 2 full threads, consider the Nylon sealing washers you mentioned. Like the bonded metal/rubber seals, they work with a lot less torque. However, they cover a larger contact area and therefore will work with that enlarged plug hole you have to deal with. You may not find one sized for 5/8". However, the 9/16"/14mm size should be available and can be worked over the coarse threads of the Mini drain plug.

[tiger99]

One version of the bonded seal, in the UK at least, is known as a Dowty seal, after its supplier, a well-known pioneer of high pressure hydraulics, amongst other things. They work rather well. My modern cars have mostly had similar seals on the sump plugs, and although you are supposed to renew them, I found that they last for ages.

If that was my gearbox, and not theoretically the responsibility of its supplier, I would get a short piece of hex steel bar turned, with an oversize thread, like a larger sump plug, only bored and tapped correct size through the middle. Screwed into a retapped gerabox with the correct sealing and locking grade of Loctite, it would be a permanent fixture, so the sump plug would, in future, be screwing into steel. Should last almost for ever.

I think someone used to make repair bushes as I have described. Maybe they still do.
.

[bmcecosse]

I wouldn't use on a taper plug - I would get another gearbox with a good sump plug, and transfer the 'new' gears to that box... I'm amazed anyone would rebuild a gearbox in a casing with a knackered sump plug. To say I'm dubious is the least of it.....