Drilling diff drain plug out

ralphr1780 · Post by **ralphr1780** » Mon May 30, 2016 9:24 am

Some 23 years back the diff was drained then powder coated with the fill and drain plugs fully tightened. At that time, upon IRS assembly, the fill plug was easily pulled out and proper oil filled in.
Last week-end decided to drain and refill with fresh oil, but the drain plug would not undo. I am using a 8 points socket which would normally undo this type of plug, but hopeless here. After an hour of struggle, even downsizing to a smaller socket and forcing in on the plug, no success at all.
All recommendations, ideas, tricks, to get this plug out are most welcome!

Post by **mgcjag** » Mon May 30, 2016 9:46 am

Hi Ralph....have you tried someting like a small dremmel/grinder to remove the powder coating around ghe plug.....if you really want it out then you may just have to go for it..a socket on there and a bar and hit it with a big hammer......but it the thread strips you will have to re tap etc......or you could try to suck out the oil via the vent pipe or fill plug

ralphr1780 · Post by **ralphr1780** » Mon May 30, 2016 10:05 am

Hi Steve, did go first with a sharp blade around the plug to cut the paint, on second attempt gave it a go with the dremel.
It is really stuck in hard.

PeterCrespin · Post by **PeterCrespin** » Mon May 30, 2016 10:58 am

ralphr1780 wrote:Hi Steve, did go first with a sharp blade around the plug to cut the paint, on second attempt gave it a go with the dremel.
It is really stuck in hard.

Impact driver? A big enough one will snap the plug off, which at least means it really, really was stuck (and start the process for drilling and tapping a replacement smaller drain)?

Post by **mgcjag** » Mon May 30, 2016 2:28 pm

Hi Ralph....you have to decide if you want it out with the risk of snapnig/stripping the thread with as Peter said inpact driver or socked bar and hammer.....or suck the oil out....just stripped the suspension down this weekend on my Jeep....there were some really tough nut...but a big bar and hammer loosened them....not one stripped or snapped....good luck

paulsco · Post by **paulsco** » Mon May 30, 2016 8:46 pm

Try tightening it up a fraction and then undo it; it is amazing how often this works.

Paul

PeterCrespin · Post by **PeterCrespin** » Tue May 31, 2016 1:53 am

paulsco wrote:Try tightening it up a fraction and then undo it; it is amazing how often this works.

Paul

It does indeed - on parallel threads. Not so much on jammed-tight taper plugs... But then in extreme cases anything is worth a try.

ralphr1780 · Post by **ralphr1780** » Tue May 31, 2016 7:43 am

Have tried the tightening, it is not moving one single degree.
Also, hammered it with the socket fitted, heated the block around and used cooling spray, to no avail.
Coming w-e will be clearing the exhaust pipes out of the way and go with a flat sharp chisel, last resort before drilling.
Thanks for the response, will keep you posted with pics.

Post by **mgcjag** » Tue May 31, 2016 8:07 am

Hi Ralph...the chisel will definatly ruine it.....try a longer bar for more leverage

ralphr1780 · Post by **ralphr1780** » Tue May 31, 2016 9:18 am

Steve, the long bar will not help as the 8 points socket is each time eating a bit of the plug head, forced the downsizing from 9/16 to 1/2.
I guess going with a chisel on the widest part of the plug is likely to get it a bit moving, at least I hope so.

PeterCrespin · Post by **PeterCrespin** » Tue May 31, 2016 10:02 am

If it is still driveable and you have a socket that fits (or a large stud extractor type socket with teeth inside) try driving it to a tyre place or an engineering place with a powerful impact wrench? I suppose you should take some oil and a new plug in case thry are successful...?

paulsco · Post by **paulsco** » Tue May 31, 2016 12:17 pm

I?ve never had a great deal of sucess drilling out broken or seized bolts; it is very easy to stray and damage the treads.

I have however had a lot of success on broke bolts; MIG welding on a washer through the hole (so as not to damage the surrounding area) and then welding on a nut. This has the double effect of heating the bolt and also allowing additional purchase on a larger nut.

In your case, if the top of the plug is protruding, you could perhaps find a larger nut that just goes over it and weld this on.

Paul

PeterCrespin · Post by **PeterCrespin** » Tue May 31, 2016 12:53 pm

It's probably a cast iron plug if it has the square protrusion, but braze might still work, if the heat doesn't cook the nearby seals. I wasn't thinking of drilling out the whole plug (tapered female threads would be a bitch anyway). I was thinking if the square stub crumbled away you could face the remains flat and drill/tap for a smaller drain in the body of the plug. A bit like the small drain in the later petrol sumps?

mylesw · Post by **mylesw** » Tue May 31, 2016 1:01 pm

Have you tried to chemically remove the powder coat? A long time back I had a chassis powder coated and had to remove the powder coat from the front suspension mounting points. I used spray on gasket remover to do this and it worked really well. Spray on the gasket remover, wait 15 mins whilst the powder coat softens, remove and repeat...

JagWaugh · Post by **JagWaugh** » Tue May 31, 2016 1:07 pm

Before you risk damaging the square any further, go to a specialty tool shop and get a square socket. Use that with a breaker bar.

Andrew

Post by **mgcjag** » Tue May 31, 2016 1:20 pm

Hi Ralph....once you have it out have a look at tbis thread....options for new plug viewtopic.php?t=8041&highlight=drain+plug

ralphr1780 · Post by **ralphr1780** » Sat Jun 04, 2016 8:47 pm

The bugger is out, on the left next to the fill-in one.
The PO had opted for Teflon thread insulation:

It took a couple of chisel knocks to get it twisting a bit, then with the metrinch socket (12 and not 8 points as stated earlier).
Next step in the refill!

paydase · Post by **paydase** » Sun Jun 05, 2016 12:15 am

Well done!
Could you still measure the correct size of that square, in case one wants to remove his own one?
1/2" would be nice but doubtful, I see this thread with some related discussion and the size is unclear but might be 9/16.
viewtopic.php?t=8041&highlight=drain+plug
Also it is not mentionned in the SNGB catalogue where the reference seems to be HA-059...

Post by **mgcjag** » Sun Jun 05, 2016 8:36 am

Hi Serg....in the link you give it does say that the head of the plug is not square and is a diamond shape, thus making it difficult to find a tool to fit...so one tool does not fit all..best to try on your own diff......most of the ones i have seen and worked on and slightly damaged

paydase · Post by **paydase** » Sun Jun 05, 2016 1:37 pm

I hope the following may be useful.
Here is a pic of the (apparently square) diff drain plug on my car:

And here is the measurement of its size:

Reads close to 13.5, so would be 17/32".
A 13 spanner didn't go and a 14 was obviously too loose and would damage the plug.
Why on hell using such an exotic size?

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