Removing gearbox filler plug... how do I?

[NMX516]

Hi all,

I went to change the g'box oil last w'end and do you think I could get the filler plug out?? Nope!

So anyway, just wondering what methods and tools people use for this. As it is a square shaped plug, sockets won't fit, the adjustable wrench was near useless, none of my ring spanners fitted properly, and the open ended spanners just seemed to want to round off the edges of the plug...

Am I missing something here? Is there a special tool that should be used, or a certain sized spanner? I just didn't feel that my spanners were gripping it well enough, and have the battle scars to prove that a couple of attempts ended in the spanner slipping off the plug.

Any ideas on the best way/correct way to do it would be greatly appreciated.

cheers

Gerard

[JBT]

I used a big shifter on the NA. If you've rounded the edges off the plug, you may need to look at using a Stilsons (pipe) wrench.

[Sheck]

remember to spray some penatrative lube all over it and let it sit for a day/overnight before you try again. I will be a million times easier.

[NMX516]

Thanks JBT and Sheck. I haven't rounded the plug to any great extent, which is the main reason I stopped and thought there must be a better way. The plug is still very much square!

[green_comet]

Thats the same problem i had when i first got my car, the thread is tapered and locks in very tight if you get too carried away. I couldnt get anything onto it to get it loose (as it was rounded by the last person who tried) so i went down to the local ultra tune. They popped it up on the hoist and got some pretty big multigrips onto it, is eventually came loose after about 30min of trying.

I then replaced the plug, and made sure that i covered the thread with some anti-seize when putting it back in. The anti-seize will make sure this never happens again..

Hope this helps..

Cheers
Ryan

[Wuey]

Have to ask - righty tighty, lefty loosey?

Try a 30cm shifter first. If that fails, use a 6-point 14mm socket with a long socket drive. If you don't have a long socket drive, slip a length of cheater pipe over what you have for better leverage. If that fails again, use a monkey(plumber) wrench as a last resort. You might need a new plug after the monkey wrench has done its deeds. For easier removal next time, just snug it back a smidgen. It's a self tapering bolt which is unlikely to come undone. You can crack the gearbox from over tightening.

Note: NEVER EVER use a normal 12-point socket on the tranny plug.

[NMX516]

Thanks Ryan, the anti sieze sounds like a good idea.

Have to ask - righty tighty, lefty loosey?

Yep definately was trying to turn it anti clockwise thanks Wuey

I think I will buy a new plug in anticipation of wrecking this one, then use some anti sieze on it. That way, I can also then justify the use of a stilson if needed

[irwin83r]

if your finding it hard try hitting it. a sharp wack straight onto the offending plug will often work best. basically what happens is the sharp blow directly down on the head of the plug compresses the crap in the threads and when it springs back it becomes loose. alternatively try using a file to freshen up the flats of the plug and get a open ender or ring spanner (i'd use a ring spanner if it fits well but if its only a square headed plug a open ender is probably better) that fits well and give it a couple of hits anti clock wise.

if that dosnt work and theres no flats left at all and you dont a have a Super tool (yes those demtell things) then you can try using a chisel and a hammer and knocking the plug around.

at work thats what id do anyway.. but at work id also use an oxy torch on it before going for the chisel but not sure if thats a good idea on the bottom of your car.


never under estimate the hammer

[Insurgence]

i found it difficult to remove my trans. plug as well.

ended up using a 12 point (should have used 6, i took a risk) and got my friend to operate the breaker bar from outside the car while i held the socket in place.

the problem is that the bolt head is too small and its hard to turn the socket without it slipping off. with the person outside the car turning the breaker bar in the correct direction i managed to get mine off first go.

aside from that i'm pretty sure the right socket on an impact wrench would get it off in a jiffy.

....

oh i read your post again you mean the filler plug of course...
i used a shifter on mine. always tighten the shifter while wiggling it back and forth so it is really tight on the bolt first..

[Xaviien]

Have to ask - righty tighty, lefty loosey?

Try a 30cm shifter first. If that fails, use a 6-point 14mm socket with a long socket drive. If you don't have a long socket drive, slip a length of cheater pipe over what you have for better leverage. If that fails again, use a monkey(plumber) wrench as a last resort. You might need a new plug after the monkey wrench has done its deeds. For easier removal next time, just snug it back a smidgen. It's a self tapering bolt which is unlikely to come undone. You can crack the gearbox from over tightening.

Note: NEVER EVER use a normal 12-point socket on the tranny plug.

For anyone that finds this thread through Google, on an NA, a 14mm socket won't fit. A 16mm is too small and a 17mm socket is too large.
I used a 14mm metrinch spanner, then used a commodore jack to crack it, raising the commodore jack using my socket wrench. It wasn't as hard to undo as the diff plugs (the jack almost lifted the car before it would crack) but it was too hard to undo by hand, and not enough space to get a bar on.


Sorry for the thread necro, but this is one of the first hits when googling "removing mx5 gearbox filler plug" so I figure a bit if necro would be ok.

[hks_kansei]

I just used a regular old open ended spanner. Can't remember the size, just used whichever one fit snugly.

I would really recommend against using sockets since they'll only ever grab the corners, and if it's stuck hard they'll just round them off.


Open ended spanner of the correct size, stilsons, or a sump plug remover (old fashioned tool that often has a square socket on it specially for the task)

I don't remember having any issues getting the fill plug out of my gearbox or diff, but then the car only had 80,000km on the clock when I did that.

the obvious thing of always remove the fill plug first applies here too, never remove the drain without first having removed the filler.

[Xaviien]

Yep. I agree with you 100% HKS.

Sockets are absolutely no good, and I'm SO glad all the MX5 tutorials mention taking out the fill plug first!

[YanMa YatTai]

I bought this 8 point socket http://www.protoindustrial.com/en/industrial-tools/Proto/Hand-Sockets/Sockets/fa667508-1eee-43f0-8e2b-e55b6d4134f0_Proto%C2%AE-1%7c2%22-Drive-Sockets---8-Point/J5418S_Proto%C2%AE-1%7c2%22-Drive-Socket-9%7c16%22---8-Point/
From these people http://www.henchman.com.au/landingpage.php

Expensive yes but is the correct socket.

[NMX516]

Holy thread revival batman!!

[Purfler]

All the above. Just to get this off my chest, I had similar problems with our Subaru Forester and I actually relented and took it to a mechanic who put it up on a hoist (great advantage), hit them (GB and diff plugs) with a largish hammer and then used a 3/4" square drive breaker bar. The sube uses an enourmous torx drive plug in the GB (T72 I think. Very hard to get). THe diff is recessed 1/2" drive. I had the back of the car in the air with a jack under my breaker. I stopped as I thought I would break something other than the seal on the plug.

Tim