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Well, some systems have a screamer. At the end of the rubber hose coming from the top of the radiator there may be a metal tube that is litteraly a whistle.
Cheesy at best.
If you want to see temps the best thing to do is install an electric temp guage kit. I put this one on my L175 when I built the engine back and I love seeing my temps.
The sender is mounted beside the upper radiator hose neck on the cylinder head to get the hotest temp readings.