Freeze Plugs

Not on the 5, but my wife's previous car had a leaky core plug, eventually resulting in such rapid coolant loss that we had to refill it halfway through a 10-mile trip to the garage.

Gaining sufficient access is the usual problem; then you just drill the plug, yank it out, clean up the hole and bang in the new plug with the right size drift. We let a tame professional do it; it was about a pound for the plug and 90 times that for labour.

A common cause (as it was in that case) is missed coolant changes; the head gasket may not be far behind, if you're really unlucky. I know the HG on hers failed a month after she sold the car (an old Citroen diesel). It had a cooling system of such terrible design that no service mechanic had dared empty it for fear of airlocks. Citroen suggested the use of a header tank high above the engine bay, sealed to the filler neck, and even then it was tricky.

Thanks for the info... As it turns out I had to pull the airbox out a few times (once to replace the hoses and once to find the leaky plug) so I can do that in about 5 minutes. With the airbox out of the way I've got about 12 inches of a straight shot to install the new plug... That's like miles after working in the console or under the dashboard! After years of running straight water as coolant I doubt it will be long before others corrode away, I may get them done in ~5000 miles with the timing belt, water pump and other things. Considering the abuse I've put Bambi through:

M y I t's A T ough A utomobile !

Ephar & Bambi '92 A Classic Red The Original Winkin' Miata Limping at the moment, Waiting on parts, Looking forward to Dancing again!

Not to mention anything made of aluminium. Expect the water pump & head to have some serious corrosion as well!