Transmission Oil Change - Worked like a charm

[maxm50]

How about trying a small brass-bristled brush or small metal picks to clean any dirt/gunk out of the threads? I just did that on my recent oil / trans fluid change. I also replaced both plugs because they had some mangled threads from previous owners pipe-wrenching on them. After that, the new plugs went in quite well.

Rotate the brush counter-clockwise so you're pulling gunk out of the pan, not pushing it up...

I'm with the others - using a tap to clean pipe threads should be a last resort...

[DieselSpider]

How often? Well it probably has never been done since 1973, so about once every 47 years?

I have a brand new plug as shown a couple of posts above, but it will only screw in a few threads before it binds tight, and the plug is sitting very proud of the differential.

Think this is what I am looking for:

https://www.ebay.com/itm/M22-X-1-5-Metr ... 1536115003

All comments most welcome!

That is as it should be as there is plenty of wear left in the taper. If it seals then leave well enough alone is the best advice I can give you.

The plug tap you linked to is for mild steel and other soft metals so may not be able to do much on the differential housing if it actually needed remediation except for jam potentially breaking off when you attempt to remove it and the last thing you want is to have a mild tap break or otherwise fail inside a hard metal. Even the one I linked to would only be good for the engine oil pan and aluminum transmission housing. Having a tap fail and jam inside something can be very, very difficult to remediate afterwards and can require taking the item to a machine shop for repair if you do not have the tools and know how to fix it yourself.

[tima01864]

Are you sure the differential uses a tapered plug? On the midwest site there are different plugs for different components. I would take the time and call or e-mail Midwest to make sure before you do something drastict.

[Nanonevol]

I gave up trying to get off my differential drain plug and siphoned the old oil from the fill. Yes, thick oil will siphon, but slowly. After several hours I got the 3 pints or so out.
Not optimal surely but good enough for my standards on this '77 Spider.

[18Fiatsandcounting]

I gave up trying to get off my differential drain plug and siphoned the old oil from the fill.

Just curious here. Was the plug welded in or rounded off or something goofy like that? Since there's plenty of room down there, I have never had a problem with a 17mm hex socket (6 point, not 12 point) with a 1/2" drive and a foot long pipe on the ratchet handle for extra leverage.

-Bryan

[Nut124]

Even if the drain plug is rounded it should come off with large, quality visegrips.

Just be careful and secure the car on blocks so it will not drop while working on it.

[DieselSpider]

Are you sure the differential uses a tapered plug? On the midwest site there are different plugs for different components. I would take the time and call or e-mail Midwest to make sure before you do something drastict.

I'm 100% sure that my 1978 with the front load diff has a tapered pipe plug on the drain sticking out the bottom of the housing. The head is smaller than the threaded area and there is no flat seating area or gasket of any kind. Calipers indicated metric pipe taper 22mm threads and pitch gauge indicated 1.5.

It was in so tight it felt like they put it in with an impact wrench. I had to use a breaker bar with a 6 point socket in order to remove it.

[tima01864]

"Always remove the fill plug first"
A little Pernatex on the threads helps to seal the plug, That is what I use on plugs

[SteinOnkel]

Are you sure the differential uses a tapered plug? On the midwest site there are different plugs for different components. I would take the time and call or e-mail Midwest to make sure before you do something drastict.

It would not seal without a tapered thread.

[Vintageant]

Ended up using a 22mm 1.5 die on the plug to clean it up. Now it runs much deeper into the diff.

[DieselSpider]

Ended up using a 22mm 1.5 die on the plug to clean it up. Now it runs much deeper into the diff.

Just use a little temperance and resist the urge to bottom that tapered tap out. You really do not want it to run a lot deeper and just want enough clean taper for it to seal. I used to maintain a lot of pipe and antique fixtures and it was a royal pain to have to deal with someone who tapped tapers too deep as then I would have to weld or cast new material into the irreplaceable housings, re-bore and then put in new correct tapered threads. I was dealing with items that were just over 100 years old in an industrial setting however a taper is a taper and you really do not want to cause 50 or 100 years of wear in one thread cleaning operation.

After tapping you need to flush the differential out with kerosene, brake cleaner, etc to be 100% certain to get all the chips from the tap out of the housing. I would not rely on a magnetic plug to eliminate having to flush the differential after a tapping operation either.

[QuintupleTurbo]

Hey gang, in the spirit of keeping things organized on this forum, I'm going to breathe some life back into this thread

In terms of the transmission, I cant get my 17mm socket and my torque wrench to fit in the space where the fill plug is, but I can get a traditional 17mm wrench in there. Is torqueing this plug to spec important? If it is, I'll pick up a 17mm torque adapter, or a 17mm crowfoot wrench.

I also just ordered a jar of Permatex aviation. Should I be applying some to the threads of the fill plug for a better seal? Will it be a PITA to remove once it cures?

And last but not least..I think the rear of my transmission pan is leaking, but I can't tell from where. I've checked to make sure all of the nuts are torqued down, and I'm wondering if I clean off the outside, could I use permatex aviation to put a sealant layer on the outside of the pan? Wondering if this will do any good. Otherwise I will order a new gasket.

[geospider]

tighten like you would an oil drain plug. I wouldn't use any tread sealer