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Stuck oil fill plug

Posted: Sat Jun 01, 2013 12:55 pm
by Squiggas
While changing the oil in my wheel hubs I found that one of the oil fill plugs was stuck. So, I thoroughly cleaned out the inside of the hex hole with a small screwdriver, got a 10mm hex key with a half inch socket drive and used a hammer to firmly seat it as far in as possible. Then I attached a 70cm breaker bar and it still wouldn't shift. With two hands and a mighty pull it turned. Or rather the hex key turned - not the plug. Now I have a stuck plug with a round hole.

I'm thinking of getting a screw extractor (the type with a tapered end and reverse thread) to see if that works, but I'm worried that it might do more harm than good.

Any suggestions?

Re: Stuck oil fill plug

Posted: Sat Jun 01, 2013 1:27 pm
by ccalingaert
I had the same problem with one of the differential plugs and managed to get it out with an extractor after a long soak with SiliKroil penetrating oil. Once you finally get it out, put some anti-seize on the new plug to avoid a repeat occurrence.

Re: Stuck oil fill plug

Posted: Sat Jun 01, 2013 1:30 pm
by Stekay
I had the same issue when I first got my Pinz. Obviously WD-40 or Kroil will help. I used my impact gun and the plug came right out. If you don't have one, try giving it a few hard raps with a hammer. Hope that helps. -Steve

Re: Stuck oil fill plug

Posted: Sat Jun 01, 2013 1:36 pm
by pcolette
EI sells replacement drain/fill plugs with a standard hex head instead of the allen oem plugs ... -Head.html

A definite improvement and makes future access much easier.

Re: Stuck oil fill plug

Posted: Sat Jun 01, 2013 1:47 pm
by Squiggas
Wow - only a few minutes since I posted the question and suggestions coming in already. Gotta love this forum!

Chris - did you drill the plug to use the extractor or was the existing hole enough?

Re: Stuck oil fill plug

Posted: Sat Jun 01, 2013 1:50 pm
by 4x4Pinz
I have shown several pinz owners how using an old socket and a hammer will loosen the plugs up. The plugs get to a point where no matter how hard you turn them they will not move but with a well placed whack with a hammer they come loose very easy. All you are trying to do is break the bond of the copper crush washer and the housing. I know people don't like to see or hear about the use of a hammer on their pinz but it is the proper tool for the removal of these plugs. The key is to use a socket (or other implement) so as not to damage the hex hole and insure the hit is placed on the plug and not the surrounding housing. Very simple but very effective.

If you go ahead and hit the plug as described you should be able to use a sharp chisel and drive the plug around. It will only need a slight turn then it will easily come out. You will of course need a new plug. The style you choose is up to you.

Re: Stuck oil fill plug

Posted: Sat Jun 01, 2013 5:26 pm
by ccalingaert
I got lucky and had an extractor that fit without drilling.

Re: Stuck oil fill plug

Posted: Sat Jun 01, 2013 7:22 pm
by krick3tt
I have purchased enough hex head plugs to replace the OEM plugs that when it comes time to change out the oil in the tranny and other places I will replace them.

Re: Stuck oil fill plug

Posted: Sun Jun 02, 2013 12:04 am
by Thomas-E
Some other thoughts...
When installing plugs use anti-seize compound on the threads, steel <-> aluminum fittings may damage the aluminum threads if no anti-seize and/or SCREWED IN VERY TIGHT. :cry:

I used to work on helicopters, most work (about 80%) is done with 1/4 inch drive...small bolts and lots of aluminum hardware.

What I havs done for the last 6 years,
Drain/Fill Plugs - 16-18 ft/lbs torque, use anti-seize when reinstalling

I like to use my heat gun on the aluminum case, just going around the plug and try not to heat the plug. Then give it a tap and it comes out fairly easily :D

Use new copper washers (seal rings) or anneal the old ones.

I am still using all hex-drive plugs 8)

Re: Stuck oil fill plug

Posted: Sun Jun 02, 2013 11:05 am
by Jimm391730
Now I have a stuck plug with a round hole.
1. Hit damaged plug with hammer as described already.

2. Get a cheap 1/2" to 3/8" socket reducer (with the 3/8" tip and 1/2" hole) and grind the end of the 3/8" so that the top corners are sharp; then pound into the round hole with a hammer. Insert 1/2" breaker bar and then use "two hands and a mighty pull" again.

In my case, I already had a socket reducer that I could use, plus it doesn't require you to drill through the plug and you won't have that mess of oil coming out to deal with. Sharpening the top corners of the reducer allow it to act as a broach and cut the corners into the brass plug. Pound it in a good 1/4"-3/8" (the depth of the original plug hole) for the most strength before you try it. The four corners get a better grip than the six corners of the hex hole.

Best of luck.

Re: Stuck oil fill plug

Posted: Sat Jun 15, 2013 10:05 am
by Squiggas
Two week later and it's still stuck.

I tried the hammer and chisel suggestion, and it really felt like it would work, but all I managed to do was take a chunk of metal out of the plug. So, I ordered come screw extractors and a cheap 1/2 inch to 3/8 inch socket reducer and soaked the plug in WD 40 while I waited for them to arrive.

I tried a screw extractor first, got a good grip, and with a long spanner twisted it but only succeeded in widening the hole. Then I got a heavier hammer (3 pounds) and an M10 bolt and used them to direct heavy hammer blows around the outside of the plug. The next size up screw extractor got a very firm grip and with my breaker bar I managed to make the hole even wider.

At this point the hole is too wide to try the socket reducer idea. I now have a very battered stuck plug with a gaping hole, so I think I will have to admit defeat and take it to a garage and ask very nicely if they can get it out for me.

One idea I didn't try is to get a can of butane (used to refill gas lighters) and squirt it in the hole. The idea is that it will rapidly freeze the plug and make it contract.

Re: Stuck oil fill plug

Posted: Mon Jun 17, 2013 10:36 am
by Jimm391730
Try pounding in a 1/2" short extension in place of the 3/8". Can't hurt now!

Re: Stuck oil fill plug

Posted: Mon Jun 17, 2013 10:57 am
by michaelh712
You could also try the chisel method. Take a sharp chisel, find an edge or somewhere you can make an impression, and hammer away, being careful not to damage the case. I've used this is such desperate situations in conjunction to PB and it can work.

Re: Stuck oil fill plug

Posted: Tue Oct 18, 2022 2:36 pm
by Tank
Just ran into this situation myself on my rear differential control plug...
Tried many "tricks," but what worked for me was about 24 hrs of liquid wrench, some heat from a torch, then rotational pressure from a punch and hammer. I drilled a shallow hole on the outer rim or the plug at the 3 o'clock position so the punch had a seat. Covered the axel boot and brake line with a wet paper towel and tinfoil, propane torched the plug for about 20 seconds, then did some CCW beating.
Didnt get to try the above mentioned socket reducer, and had no luck with getting a screw extractor to bite.
I have ordered some hex-plugs from EI.
Thanks for the help... love this forum!
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