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MG TD TF 1500 - Oil filter primer plug wrench size

I'm getting ready to do my first oil change on the TD (TD25009, XPAG/TD2/25404, 11 Feb 1953). It has the Tecalemit filter cannister and I'm planning on using a NAPA FIL 1300 filter based on earlier threads (Lord only knows what I'll find in the cannister when I open it up). In anticipation of needing to prime the filter/pump after the oil change I decided to see if I have a socket that will fit the primer plug. I used open end spanners to see what would fit but it doesn't look like there's room to swing a spanner so a socket seems the way to go. I have English, metric and Whitworth spanners and I expected the 5/8" Whitworth to fit but it is quite loose. 9/16" English is too small but 15mm seems to fit albeit very tight. A six point 15mm socket is too small but a 12 point fits just barely. OK, finally and thanks for your patience - the question:

What size wrench is supposed to fit the plug?


J K Chapin

Jud - it should be 5/16 Whitworth. See the chart, Wrench Size Comparison in the Other Tech Articles section of my Homepage at: If a 9/16 American is too small and 15mm will barely fit, that leaves the next step being a 5/16W. Cheers - Dave
David DuBois

Thanks Dave. Now I have a reason to pop for the Whitworth socket set. Anybody know of a better deal than the Moss set for $95?

J K Chapin

I recently bought a set of 9 x 1/2" drive sockets on a rail from Rover Parts Victoria here in Oz for $66 delivered. I guess shipping would eat up any savings though.
TD 5801
P Hehir

Contact Hugh Pite. jenntoo(at) Bud
Bud Krueger

I fount a set on Amazon for $20 + shipping (total about $35). I hope they are decent but, Hugh, please contact me.


jchapin3 at aol dot com
J K Chapin

If you do buy the high quality but pricey King Dick 3/8" sockets from Moss, buy them individually and not as a set unless you really like the little rack that comes with them. The set costs nearly $95 and the same 7 sockets purchased individually cost $85.65.
Joe Olson

I've found solid tools at British Tools & Fastners at
and British Cycle Supply at
British Tools has King Dick at prices like Moss but also other cheaper Whitworth tools... so far have worked for me. I got some great extra long sockets from British Cycle Supply. Both nice folks to deal with.
Peter Pope

This thread was discussed between 16/11/2013 and 18/11/2013

MG TD TF 1500 index

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