runs like a champ with, until right after i changed my oil?

Have an '87 325i. runs like a champ with, until right after i changed my oil.toda y i started it up, and normally the temp gauge stays low and doesnt fluctuate much, but this time i let it warm up for a fraction of the time, and the temp gauge was already like halfway up. felt the hood and it was hot, as never before. i had to take it for a short drive to cool it down. but this is only the half of it. at the same time, my valvetrain is tapping significantly, as opposed to before. this all happened suddenly, after i gave it a fresh oil and filter change. may i have knocked something out of place when changing my filter? IDK. the tempurature regulation is surely acting up, this i know. but what about my engine? is there a chance i have damaged my valves permanently? the oil stick is reading just a quarter inch or so low-could that be causing inadequate lube to the valves, thus causing them to be noisy? tapping?I hope to all get-out that i didnt harm my engine by running it hot and low of oil.

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[Kerry at Pelican Parts]

Sounds to me like your thermostat stuck closed or water pump went bad unless you put Olive oil in the engine your lubrication system should be fine. Did you put in a thinner weight oil? Is the water pump belt still on the pulleys? As long as you did not overheat the engine you are probably okay but I offer no promises. Can you check oil pressure ? and is the oil pressure light on?

- Kerry