400 oil pan plug thread size.

SDE · Nov 30, 2014

The threads have gotten messed up in the oil pan and I need to get a tap to clean them up. I would guess 7/8, but if someone can tell me the correct size, I can borrow one from work and make a quick job of it.
Thank you
SDE

DeltaRed · Nov 30, 2014

Can you remove the plug and take it with you and 'measure' it?Do a side by side comparison.

rustyfarmall · Nov 30, 2014

(quoted from post at 09:02:51 11/30/14) The threads have gotten messed up in the oil pan and I need to get a tap to clean them up. I would guess 7/8, but if someone can tell me the correct size, I can borrow one from work and make a quick job of it.
Thank you
SDE

Correct me if I'm wrong, but I think it is 1/2" pipe. Or is it 3/4"?

charlieu · Nov 30, 2014

The parts book shows it as 359875R1 and that plug is a 7/8 X 18 It also uses a steel washer for sealing. I know that some of the older engines used a pipe plug. Pipe plugs just used the threads for sealing.

SDE · Nov 30, 2014

Thank you, I did not feel like dropping the plug today. It is only about 10 degrees out.
SDE

rustyfarmall · Nov 30, 2014

(quoted from post at 09:40:23 11/30/14) The parts book shows it as 359875R1 and that plug is a 7/8 X 18 It also uses a steel washer for sealing. I know that some of the older engines used a pipe plug. Pipe plugs just used the threads for sealing.

I didn't know when the drain plugs were changed to the much better style that used the washer for sealing. Kinda thought maybe it wasn't until the introduction of the 460/560?

randy hall · Nov 30, 2014

all of the super m's and h's that we own have the 7/8 18 oil plug. that's what the parts book shows too.

randy hall · Nov 30, 2014

the h's and m's took a 3/4" pipe plug.

Tom Dowling · Nov 30, 2014

my 400 has 7/8 thread w/ washer

D Slater · Dec 1, 2014

Like some posted it's the same size as a 7/8 fine thread bolt with a copper seal washer. Pans were changed to that type plug on SM serial 29603 and higher. Though if you have other than a early 400 the oil pan doesn't have the oil lever checks like the SM.

mkirsch · Dec 2, 2014

7/8-18. I saw them in the new Ste!ner's catalog the other day. $8

SDE · Dec 2, 2014

The threads on the plug do not look to be damaged. I have ordered a tap to chase the threads. Thank you
SDE

Nebraska Kirk · Dec 2, 2014

Jim Becker · Dec 2, 2014

(quoted from post at 21:04:17 12/02/14) Incidentally, 7/8-18 is the same size as the spark plug threads too.

No it isn't. The spark plugs are 18mm x 1.5

Nebraska Kirk · Dec 2, 2014

Oops.. sorry, I was thinking of the pre '39 IHC tractors :roll:

400 oil pan plug thread size.

SDE

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DeltaRed

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rustyfarmall

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charlieu

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SDE

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rustyfarmall

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randy hall

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