Prior to my current used BMW, the last car I wrenched on were mid 1970’s cars (Chevy and Dodge)
If I recall, they had metal radiators, thermostat housings, etc.
Do all cars today have plastic cooling systems?
If not, which are still made out of metal?
Also, what year/decade did radiators and cooling systems become plastic?
No one year that I can name.
As manufacturers are constantly looking to lighten the weight of vehicles, they start introducing an idea like that a little at a time. Kind of a real time r&d. ( another answer for the relative thinness of todays brake rotors )
Then you’ll also notice, as part numbers are superceded and made by other aftermarket sources, the replacement might now be plastic for older applications
I don’t know what the big deal is; but I would guess there are fewer problems with corrosion with plastic radiators. I don’t feel that metal is superior in applications like this what so ever. It’s more that modern plastics can handle the heat better then they could in the past and have other advantages over metal. After all, one of the most durable handguns of all time made by Glock was also one of the first to encorporate plastic into it’s entire line on major components.
My 1976 Ford Granada and 1984 Impala still had ALL METAL radiators. After that the tanks became plastic with mostly aluminum cores. Re-coring a radiator ceased to be cost-effective quite a while ago.
My '88 Escort is the first car I can remember having that had plastic tanks on the radiator, the core is also aluminum. The original radiator lasted approximately 20 years without problems, but one day when I turned the engine off and the pressure built up it cracked one of the tanks. I considered buying an all aluminum radiator, but lucked up, someone had the radiator (new) I needed listed on eBay for an opening bid of $ .99 I bid on it and was the only bidder. I think I ended up with about $20. in it including shipping. My wife has an '87 Chevy Celebrity and if I recall correctly it also has plastic tanks. I think the '84 Mazda B2000 pickup I had was an all metal radiator.
My 81 Olds had metal tanks but my 86 Buicks had plastic tanks. Nothing wrong with the plastic tanks and even just replaced one myself for about $35. Metal tanks had to be brazed on. Real question might when did they all start to be made out of aluminum? Probably the same time. Hard to braze a brass tank to an aluminum core.