S1 XJ6 Emission Thermostatic plug replacement

(Paul) #1

Finally removed that vacuum emissions thermostatic switch thing at front of intake manifold located within water jacket just behind thermostat…

Intend to of course eliminate all emissions crap and replace that with a nice brass grub screw or similar.

Nobody locally has anything, McMaster Carr online no doubt will, however I don’t know what i’m looking for.

Anyone know the thread size by chance, or know how I can determine?

Appears to be metric 21, however it may be a British Pipe Thread like other stuff.

Any thoughts or help greatly appreciated.

Note: of course the plastic cover with vacuum connections was broken off to facilitate removal.
For those unable to remember, it is facing hole, far right.

Using phone and can’t remember parts catalog site name to provide further photo reference…

(Robert Wilkinson) #2

My recollection is hazy but I’m pretty sure it’s 1/2 inch BSP. The diameter is 20.96 mm, and it’s 14 TPI. If you have a 1/2 inch NPT pipe nipple, it’s 21.3 mm diameter, and also 14 TPI, so it should look virtually identical and might fit the hole, albeit tightly.

Most of those BSP fittings used by Jaguar were BSPP (parallel; threads not tapered) but some were BSPT (tapered threads). The former use a sealing washer, whereas the tapered ones do not. If you had a sealing washer, it’s BSPP.

A brass or aluminum hex socket style pipe plug looks best IMO.

edit: with sealant you can use a BSPT plug even if the hole is BSPP, IMHO

(Paul) #3

Thank you VERY much Robert.
Great info…really appreciate.

Thank you for taking time.

Will update with what I find fwiw.

Have a nice evening.

PS: Never ceases to amaze how there is always something new to learn. Fittings and thread types, etc…no doubt a field unto itself, and also interesting.

PPS: One quick note, it is 3/4(.75) inch diameter hole.

(Rob Reilly) #4

Metric Multistandard Components has BSPP and BSPT pipe plugs.

A satisfied customer, my Mark V sump drain plug came from them (replacing a DPOs 1/2"NPT plug which was crammed in there and leaked).

(Paul) #5

Great info. Thanks. Bookmarked.

And pardon me, it appears it would indeed be 1/2BSP as Mr Robert above stated.

Hmm…I didn’t know how to measure these correctly it seems.

(Rob Reilly) #6

BSP measurement information.