There’s a brass plug about halfway up the block near the rear on the lefthand side. It can be replaced by a drain tap, but it’s probably not worth it (one less thing to go wrong?!). Better to drain through the bottom of the radiator & remove a hose to flush it out, as stated above.
Thanks for the prompt replies, and the pics great.
I’ll have a look for the plug but will probably do as John says and “just remove the bottom hose and let the garden hose run for a while”, if it does the job.
remember, though, to be sure to get all of the 'ol garden hose water out at the end of the flushing…you wouldnt want anything but distilled water or coolant in there in the long run. I did it this way too and it was fine.
What’s wrong with the water from the garden hose? I never used anything but anti-freeze and tap water and never had a problem in any of my cars from 1966 on. Cars included a Sunbeam Alpine, Fiat 124 Spyder, Oldsmobile, two Ford tauruses, a Mercury Capri, two VW Golfs and a Fiat X1/9. I only had one car that I did not use tap water in and that was a Corvair-powered dune buggy.
I suppose if the tap water you have needs chewing I’d re-think this, but otherwise there should be no problem.
It is a very common and well founded recommendation to use distilled water. And it is also often ignored with little short term impact. But, if given a choice why not? Perhaps if you were stranded on the road, but why willingly introduce any additional minerals and salts into the coolant? Especially in an aging mixed metal (aluminum and iron) system like our Elans?
Here is a very good discussion of coolant chemistry in vintage Triumphs written by a PhD Chem Engineer- team.net/sol/tech/coolant.html
My Toyota’s Manual reads - “The coolant should be mixed with plain water, preferably demineralized water or distilled water.”
Peak Antifreeze advises - "Yes, tap water is commonly used for mixing with antifreeze, however, deionized water or distilled water is preferred. Do not use water softened with salts to mix with antifreeze. "
FWIW, I agree with Marc to best remove the thermostat and flush from there.
I also seem to remember a recommendation to remove the radiator so that it can be both flushed via the filler cap and also back-flushed under pressure.
Can’t remember the reason for that, though.
I also remember the recommendation to use only distilled water when filling the system, and to preferably use distilled when topping up.
Whilst you have the system drained check the condition of the coolant hoses and clips.
Also if you remove the radiator you can wash all the dead flys and dirt off and check for damage
Clive