26 replies to this topic

[taffy1967]

Right well first of all I'm well cheesed off because I've just recently MOT'd and taxed our Mini after 3 years of it being laid up and now I have a problem with the sump plug.

Earlier today I had intended doing an oil change and draining the cheap 20W/50 oil I filled it with which was being used temporarily and as a means of flushing the engine until I was ready to fill up with the lovely Duckhams Q Classic 20W/50.

Unfortunately I first noticed all was not well when I spotted a patch of oil beneath the car and as bad luck would have it the area around/beneath the sump plug was wet with oil too.

Strange though because my sump plug hole was heli-coiled several years back after the original threads gave up, but my Mini was laid up for almost 3 years and nothing leaked in that time?

All I did a week or so back was change the oil and so the sump plug was removed and refitted with the correct copper washer and done up as usual. I've only driven it a few miles since, but now it's leaking and I've discovered that it feels like the thread has gone again. It's also strange because it appeared fine after the oil change and it certainly wasn't leaking then.

The company that heli-coiled it fitted an extra long sump plug and I know that the original plug with the magnet on the end doesn't fit properly. Or at least I could never get it to tighten when the washer was used.

But now the extra long sump plug just spins and won't tighten up properly. Well when you turn it you can feel some resistance but then it just spins again and leaving it at the point of resistance isn't enough to prevent the oil leak either.

Anyway I now need to sort it, so should I: -

A: Try using some plumbers tape on the sump plug? Would this help make it tight and safe?
B: Order a tapered sump plug from Mini Spares but be careful not to over tighten as it can crack the sump?
C: Try and get a different sized sump plug from a local motor factors like Halfords?
D: Pay to get it re-heli-coiled, that's if it's actually possible?
E: Get a road tax refund and stop using my Mini for another 3 years?

Okay the last one was a joke, but any advice would be greatly appreciated but you'd think a heli-coil would last much longer than 6 years? Especially since my Mini wasn't used for 3 of those years!

[Dan]

Helicoils are permanant, it shouldn't have failed. You need to get an engineer to look at it to see if the helicoil has moved or broken or can be replaced (the coil could be pushed right through or it could have snapped, if so it can be reset). If however the coil has worn the outer thread in the casing and enlarged it even more than the coil size or cracked the casing then the casing is pretty much scrap. You can't fit a tapered plug in a helicoil, you won't find a larger plug with a thread even bigger than the helicoil setting thread and PTFE on the plug won't help if the outer thread is gone. Actually you might find some funky larger plug somewhere but only as a plumbing fitting, I doubt you'd track one down in a car parts supplier.

[Ethel]

Difficult to say without inspecting the threads. I wonder if the helicoil is even compatible with the thread of the standard plug?

A taper plug sounds interesting, don't think you'd manage to crack the casting without some serious effort.

The dilemma is whether to pull the plug to have a look, it would make getting the car somewhere to be repaired difficult if it won't go back in.

[Ethel]

I think there's a good chance of doing something with plumbing fittings possibly just finding something that can be tapped into the box and adapted into a sleeve for the original plug. got to be an easier option than writing off the casting.

What thread is the plug 5/8 unc?

[taffy1967]

Now I am worried, but the heli-coil shouldn't have worn the casing though because I haven't had to disturb it in quite some time since the car was laid up and I'm the only one whose been doing an oil change and I've never over tightened it either.

Shame I hadn't had a complete replacement gearbox fitted back in late 2001, instead of having this one rebuilt and heli-coiled instead.

[Ethel]

I think it's fixable without too much effort it's only a hole after all!

[taffy1967]

Thanks Ethel, I do hope so and I'm certain there's no crack in the casing either Dan. I think I'll be ringing a local Mini friendly garage on Monday to see if they can help me out.

[dklawson]

As Dan said, HeliCoils are permanent. Furthermore, they are easy to inspect. Sadly, you'll need to drain that fresh oil out. With the oil drained, jack up the right front wheel so the dripping stops. Use a flashlight to inspect the insert. It should appear like a stainless steel spring wound from diamond shaped wire. Borrow a set of measuring calipers. Measure the through-hole of the drain opening. As mentioned above, the drain plug is 5/8-ll UNC. Therefore, the through-hole for the sump threads should measure close to 0.54" [13.7mm]. Likewise, take the calipers and measure the major diameter of the threads on the drain plug you removed. It's OD should be just slightly below 5/8" (0.62" or 15.7mm). All those dimensions are nominal. Let us know what the parts measure.

Ethel, the 5/8 UNC HeliCoil is perfectly compatible with the drain plug.

I do not use the copper washer. If you determine that you have the wrong drain plug or for other reasons put a stock drain plug back in, visit your preferred auto parts store and ask them for nylon drain plug washers. They probably won't have any for 5/8" plugs. Don't worry. Ask to see what they have that will fit 14mm drain plugs (a very common size). If all they have are plain nylon washers that size, buy a pack and force one of them down the threads of your drain plug. It will be very tight but it will go. However, in the nylon washers I prefer a type that has ribbed sealing surfaces and little "fingers" on the bore that allow the 14mm washer to more easily fit the 5/8 Mini drain plug.

If you change to a nylon washer you'll require very little torque to seal the sump.

EDIT: I forgot to mention. I installed a HeliCoil in a friend's Mini just last month. The guy had NO money and I ate the cost of the parts, oil and filter. He didn't even bring sealing washers like I asked him to. Thinking quickly I found that "garden hose" sealing washers were a perfect fit. In a pinch, you can find almost anything that is easier to work with than the solid copper washer.

Edited by dklawson, 22 July 2007 - 01:06 AM.

[Guess-Works.com]

I would also check the mating face of the drain hole, if there's any break out then there's a likelyhood that the plug will never seal, but as or a helicoil failing, very uncommon... I'd be more inclined to believe that the hole was just tapped out for a bigger plug and not helcoiled which has subsequently failed.

[taffy1967]

Thanks for the replies and the good news is I hadn't put the fresh Duckhams Q oil into the engine because I put that on hold until I can sort the oil leaking issue.

I think they must have fitted a heli-coil though (well they said they did at the time), because my O/E magnetic sump plug does fit but wouldn't fully tighten up when a washer was used.

Oh and just prior to having the gearbox rebuilt and the sump plug hole sorted by a local clutch/gearbox specialist, a local engineering firm had sent one of their employees out to fit a heli-coil which failed to work properly. Yes it just wouldn't stop leaking oil and so after the bloke made a complete mess of sealing it with silicone (after he'd slopped oil down my engine too), I asked for a full refund and got it.

But that was back in late 2001 and it never leaked after the gearbox was rebuilt soon afterwards.

Anyway we're off for a run to Halfords with the O/E sump plug to see if they have anything suitable in their parts department. Failing that I'll probably ring a few good garages tomorrow to see if they can offer a long term fix.

[dklawson]

Please don't forget to examine and measure the opening to your sump. I don't have a picture of the Mini HeliCoil install, but here's a very clean picture showing what an installed HeliCoil looks like on a motorcycle engine.
http://www.ducatigir...arens_mount.jpg

The HeliCoil is the silver looking spring installed in the casting. It's obvious when they've been installed. The measurements I suggested you make will at-a-glance confirm if it was the "right"one.

Don't expect the parts store to have a nylon washer that will just drop on the Mini plug. 5/8" is not a common drain plug size, nor is 16mm. If they have the nylon ones for 14mm, particularly those with the ribbed contact surfaces, you will be able to run/screw them down the Mini's plug threads with a little effort and they will work well.

[Ethel]

I think it's a fair bet they'll have put a metric helicoil in if they had to swap the plug to fit. If Taffy's luck's in it'll be the plug that's stripped.

[taffy1967]

Well today we rang a heli-coil clutch/gearbox specialist based not too far away from us (not the one who did the work several years ago though) and apart from stating that they would have done the gearbox repairs, fitted a new clutch and heli-coil for a fraction of the price we paid back in 2001. They also asked us to check inside the sump plug hole to see if a heli-coil was actually fitted and that they didn't just cut a new thread since the original sump plug wasn't reused and they instead used a larger bolt.

Anyway they said that sorting the problem would be dead easy and they'd sort it out so we could use our original sump plug with the magnet too.

Well okay they talk the talk, but after checking the hole as suggested here and by them, we'll probably take it to them to fix and I'll point out that if they do a good job that solves the problem long term then we'll certainly recommend them to all our Mini forum friends.

Edited by taffy1967, 23 July 2007 - 07:42 PM.

[redhotmini]

if you get stuck for some nylon washers i have loads in metric and imperial sizes. i can stick a couple in the post if you like.

[ImagoX]

if you get stuck for some nylon washers i have loads in metric and imperial sizes. i can stick a couple in the post if you like.

Would you guys recommend switching to nylon even with the standard sump bolt? I had a hell of a time getting it out the last time I did an oil change and even though the copper washer is not leaking (cross my fingers) I'd rather not have to torque the heck out of it every time. If yes, what size nylon washer should I be looking for to fit the standard magnetic plug, and would I use it IN PLACE OF the copper washer or ALONG WITH it? I assume I'd replace the coper w/ the nylon...