In english a rubber freeze plug, expansion plug or welch plug.

thanks

Found a couple of sites that say it's ปลั๊กตาน้ำ.

http://vallop-automechanics.blogspot.co.uk/2012/05/blog-post_7280.html

http://dict.longdo.com/search/*%E0%B8%95%E0%B8%B2%E0%B8%99%E0%B9%89%E0%B8%B3*

Found a couple of sites that say it's ปลั๊กตาน้ำ.

http://vallop-automechanics.blogspot.co.uk/2012/05/blog-post_7280.html

http://dict.longdo.com/search/*%E0%B8%95%E0%B8%B2%E0%B8%99%E0%B9%89%E0%B8%B3*

Thanks thought it was this จุกไม้ก๊อก but neither return the correct results on google search

I chuckle because I bet few Thais have ever had to replace a freeze plug on an auto engine. I grew up in a place with freezing winters and over the years had to knock out a few and knock in a few and use a few of the rubber ones.

Never did locate them in los. I did find round rubber and used a bolt and washers.