14 replies to this topic

[slegersmini]

okay so i have had a leaky gearbox (as always with a mini) i have sorted out the gearbox selecter leak but on taking off my sump plug i noticed there was a lot of wear and it looks like it has been run other the threads, i have done it up as much as possible bt there still is a leak...

Is it too risky to like tap and die it...?

should i just go for a new gearbox housing?

HELP PLEASE ASAP!

[dklawson]

The proper fix is to have a HeliCoil inserted into the drain plug tap. There are also oversized drain plugs but avoid the self-tapping ones. You may also find tapered thread drain plugs. While some people use these... I think they are a terrible idea as they tend to push outward on the casing when you tighten them... wedging the case and drain hole apart. This isn't good in aluminum.

Another possibility for you since you still have some threads left is to replace the copper sealing washer with a bonded metal/rubber seal. Though snug, you should find that one for a 14mm drain plug will work. These things look like a steel washer with an o-ring glued into their center hole. The rubber forms the seal and much much less torque is required to seat them.

This is the only picture I could find quickly on the net. It's not a Mini sized part but you can see the rubber bonded to the center of the sealing washer.
http://ebay.stillsun...13-SH-RM-17.jpg

[slegersmini]

right okay because me and my dad have been talking about using a helicoil in there to get it fixed in better even the recovery man said about it last night on the way home!

What a waste of £15quid on oil hey?!

right i think i will go for the helicoil option as i dont fancy doing it over and over again, and my dad has done this with a lot of parts on his motorbike so that should be okay...

now just got to find the mini sump plug size... Any pointers?? and maybe some for where to get the helicoils from?

cheers!

[dklawson]

I am geographically not in a position to suggest where to buy the HeliCoils. Over here... I can buy them at an agricultural supply company or mail order them from Mini Mania. I suggest you contact Mini Spares (on the telephone) and ask if they carry the HeliCoil kits. Be prepared. Though your dad may have used HeliCoils on motorcycles, the ones for the sump plug (5/8-11 UNC) will be much larger and the complete kit (tap, insertion tool, inserts) will cost a lot more. With most kits you still need to order the drill bit separately (17/32" or 13.5mm drill bit).

Since your father has done this before he'll be familiar with the steps and process. There are two things I'd suggest he keep an eye on.
1) Make sure you tap the hole perpendicular to the gearbox casing.
2) The inserts are often a bit too long. Measure the thickness/depth of the gearbox casing at the tap location and cut a bit off the HeliCoil insert length (Dremel tool with cut off wheel) so it is slightly shorter than the tap. You want the insert to sit just below flush on the sealing surface and not quite poke through into the inside of the box.

In closing, if you go for the HeliCoil solution, the sealing washers I suggested earlier will no longer be any good as the rubber will be landing on the tapped hole for the insert... not on the smooth aluminum sealing surface. In that case, either stick with the original copper sealing washer... OR look for nylon washers that will fit the Mini drain plug. It's a lot easier to get a seal with a plastic washer (less torque) and the plastic will comply with the mating surfaces better if you don't tap the hole perpendicular.

[m1n1]

your in southend like me. South essex fasteners is the place to go. . In temple farm industrial estate.

[slegersmini]

your in southend like me. South essex fasteners is the place to go. . In temple farm industrial estate.

Oh right okay i will give them a call thanks buddy!

[GraemeC]

One word of warning with using helicoils to repair a sump plug thread on an assembled engine:

The last part of the procedure of inserting the helicoil is to break off the tang used to screw it into place. 95% of the time this tang will be lost into the internals of the box!!

[slegersmini]

One word of warning with using helicoils to repair a sump plug thread on an assembled engine:

The last part of the procedure of inserting the helicoil is to break off the tang used to screw it into place. 95% of the time this tang will be lost into the internals of the box!!

right so are we saying it would be safer to just use a whole new housing on the gearbox if i can get one for a decent price?

i really dont know what to do its costing me a bomb in train fares to get two and from work... hmm
i phoned the essex fastners and they said they would get back to me this was about an hour and a half ago!
i have searched around and i just cant find all the bits i need :/ goshh... im really stuck!

[m1n1]

there's a load of them just behind the counter on a nice display stand! just go there.

How big is this bit that breaks off? if you poor oil into the sump i bet it will come out with the flow.

[GraemeC]

The bit that breaks off is around .5mm x .5mm x 8mm not big but enough to damage bearings etc!!

If you were to fit a magnetic sump plug it might pick it up straight away.


The helicoil kit you need is on this page:
http://www.minisport...15#aTOL1REC2515

[koss]

Another alternative is to remove the box and have it alloy welded, re drilled and tapped.

Not quite the same sump but a one I repaired last week on a new beetle.



I know this may take time but it does work and will save going to the expense of a new box.
Personally I don't like the idea of a helicoil and a frequently removed bolt.

[slegersmini]

right okay thats real helpful guys.
if i had the time i would get everything re welded but i need my car back on the road asap as i dont have another one and trains and busses are expensive these days!

i think i shall be going for the minisport kit. i phoned essex fasteners the guy said he didnt have any in stock took my name and number and phone be back but i havent heard anything from them at all.

i think i shall order it tonight when i get back from work after eight!

then hopefully that should sort all my leaks in the mean time...

i have a magnetic sump plug on there aready and that usually collects metal from gear crunching so it should hopefully be okay!

thanks for all your help guys i shall keep it posted on here how i do!

Maybe this week can get better afterall! hehe

[dklawson]

Save money and time, use the HeliCoil kit. The time and labor to install a new casing is going to be MUCH greater. Removing and welding up the case is NOT a good way to spend your money. Having the case welded up and re-tapped will cost you MUCH more than the HeliCoil kit.

As for the insertion tang that you must break off... do NOT loose sleep over this. The instruction show using a drift to tap the tang off the insert. There is a MUCH better way. DO NOT tap the tang off with a drift. Grab it with needle nose pliers, wiggle it (in and out) until it snaps off, then pull it out with the pliers. Remember, this is a rather large hole for the oil drain... you have room to use the needle nose pliers in place of the drift. Were this an M6 tap or something the story would be different.

As for using a magnet to retrieve the tang if you do use a drift, maybe... or maybe not. The HeliCoil inserts are stainless steel. I forget which grade but if they are magnetic, the HeliCoils will be only slightly magnetic.

[slegersmini]

okay well once i had got the tool which didnt take too long, (local fastners come up trumps) i then removed the engine and got to work. you cant do it properly with the engine in as the tap wrench fails the front subframe completely, even with one of the arms removed.

it took around 20-30mins for me to do, mainly because the missus had text fingers and every two seconds i would get a text message from her!!

but i got it all done and it looks quite smart, i have some pics which i will post up wen i get the chance!

i took the opportunity to de coke the pistons block and head, and re seat the valves and once it was all assembled i re set the valve clearances.

the engine is all back in there and now all i have left to do is to connect up my new exhaust get a new thermostat housing bolt and then connect up my carb and once its filled with oil and water i am all done! finally!

thanks for all your help and advice guys!

i just hope i get through this mot at the end of the month.... more importantly i hope i get to and from L2B haha!

[dklawson]

HeliCoils can be inserted in the drain hole with the engine in the car, I've done it for a friend's car. Regardless, I'm glad you got the problem fixed. With all the additional work you undertook with the engine out I'm sure you'll be quite happy with the results.