I need your help and advice. My question was not found in the FAQs.

I have a 1980 242 DL with an M45 manual transmission.

I found the fill and drain plugs. They're square shaped with a bit of rounding off.

I'd like to change them out and install bolts so that I can use 6-point sockets to avoid rounding them out in the future. If this is possible, what are the specs for the threads and the length of the bolts?

Also, because the FAQs are dated, I'm wondering if there are any newer synthetic transmission fluids out there that would work in my M47?

Thanks

Hi,

You could try finding pipe threaded plugs that have a hex or Allen internal socket in the center.
Then you can use an Allen head bit made into socket wrench with a ratchet.

Most industrial hardware places have pipe plugs with square heads.
You can try McMaster Carr or the Fastenal company that cater to plant maintenance departments.

These are used in places where a flush appearance is wanted or linkages or something else has to pass in front of the plug hole.

They are usually made out of better quality steel.
They cost a few cents more but they will a be better choice than any funky plumbing parts down at Billy Bob’s hardware!
The plumbing industry goes out of its way to make things as thin as possible and out of garbage materials. They make things just a little too odd ball so nothing else fits or to be as cheap as they can be for their profit margins. The next thing their out of business or obsolete.

Yep! Square heads are from the of many years past.

""""1980 242 DL with an M45 manual""""

This a a 4 speed tranny without an Over Drive --- The M46 has an OD attached to the rear.
.The M47 is a true 5 Speed found in 1987 and later 240s


Both can use Redline MTL or the Volvo Manual Trans Fluid ---which are more or less the same specs.

If your 1980 has an M46-- with a OD, then what Dave says AT trans fluid - is what you should use... because of the OD. And this would be different than the fluid for the M47.

I have a 1980 DL with the 4Speed, and an 87 245 with a 5sp

http://www.vivaperformance.com/genuine-volvo-manual-transmission-fluid/

https://www.ipdusa.com/products/6980/106979-redline-mtl-manual-transmission-oil

CB caught my mistake - must have been sleeping when answering the original post which clearly stated M45 - and I clearly indicated my own M46 -- ooops! Sorry if I caused any confusion regarding oil in an M45. - Dave

Dave,
until we get a response. I'm not sure what tranny he's got.

First post: M45, then asks what are newer sythetics that he can use in an M47.

Then in a response to you, writes: "Thanks for your reply and catching the typo about my transmission"

that's why I listed all three trannys in my response to the Orig Post... nothing to do with your response

cheers

"I'm not sure what tranny he's got." True enough till he confirms. But with an educated guess I'd say his typo was in the text rather than the title. An M45 would still have been common in a 1980 - not so much or even available (?) '81 and up. Guess we'll have to wait and see :-). And meanwhile - according to the owners manual the 4-speed takes .8 quarts or .75 ltr of either SAE80W/90 or SAE80/90 transmission oil. -- Dave

It's an M45 Transmission

PS
on my 80 M45 - I use a flat jawed Pipe Wrench --- look in Plumbing at the hardware stores....In the Way Way Way back - once called a Monkey Wrench...as in "don't throw a Monkey Wrench into......"

Vintage
http://i.ebayimg.com/00/s/MTIwMFgxNjAw/$T2eC16RHJHYE9nzpdVDFBQqkQpNyfQ~~60_35.JPG


modern
https://www.reedmfgco.com/en/products/wrenches/smooth-jaw-wrenches/

I drive a 1980 245 M46 also. I can't tell you the thread (I think it's like a pipe thread) but what you need is the proper tool. You can purchase an 8 point socket and have no need to change anything. A 7/16th" size socket should work just fine. If there's such a thing as an 11mm 8 point socket that would work too. OR -- back in the old days when square shaped drives were common (tranny and diff plugs, brake shoe adjusters, etc) you could buy a wrench with boxed square ends.
I've always used a normal Type F auto trans fluid in mine (310k) but I would think a compatible synthetic would be ok -- unless -- the synthetic is not compatible with the OD conical clutch. Maybe someone with experience with that aspect will post. Also -- I think you meant to type "M45" - not 47 in your last sentence. -- Dave

Thanks for your reply and catching the typo about my transmission.

Both plugs are square shaped, so I don't think that a 7/16" wrench would work.

I would not want to use an 8-point socket, because I'm concerned about further rounding off the heads.

Earlier today, I practiced loosening the fill plug with a crescent wrench, carefully connecting three of the four sides of the bolt head to avoid rounding off anything.

Despite having used anti-seize on those threads last time I changed the fluid, it was hard to remove (but the threading was intact).

You did not understand my reference to a "7/16th" wrench. That would be the designation of size of a 7/16th 8 point socket -- in other words the square end of the plug is a 7/16th" square. An 8 point socket is meant to fit onto a square plug. 11mm is very close to 7/16th" - I don't recall which is the slightly smaller dimension - so one might work better than the other. Also - as I mentioned - there are-or were boxed end wrenches made with a square opening. My guess is you are over tightening the plugs. A quick online search turned up numerous 8 point sockets (not metric as far as I went) and also ratcheting 4 point box wrenches. - Dave