I don't think there is one for the OE alarm, I have the following for after market alarms - http://www.mgf-tf-central.co.uk/ht-electrics.shtml?zoom_highlight=coolant+alarm

 

I got my alarm from Phil (philmgf), but am ashamed to say I haven't got round to fitting it yet as I promised him an in-depth How To when I did. I was holding off until I did the service, so I could refill and bleed the coolant in the process.

Might be some useful information in his thread below

http://google.mg-rover.org/showthread.php?t=307657

 

Thanks Pete might be worth pursuing given my coolant pipes have seen better days.

 

I bought the lolarm 2, works like a charm. Easy intructions are included.

 

I got myself the kit from MG-ROVER SOLUTIONS, mostly OEM parts, VERY easy to fit, comes with full colour photo istructions.

 

I have the B&G low coolant alarm now and it's a great piece of kit, fitting instructions and photos are in the .pdf below, it's about an hours work once the engine hatch is off.

http://www.ukmgparts.com/PDFs/bgf1111.pdf

 

Smeak to Phil and Andycolm.

Andy fitted mine and it's fab