I have an 06 toyota highlander with 124k miles and whenever my engine is warming up to operating temp i hear it start to rattle at about 1000 rpm but when it gets to 750 ish it stops. What could it be?
Video: https://youtu.be/41Wd2GobBY8
Does it do it only on a cold start? On even when the engine is already warm?
Generally that's hey stuck timing chain tensioner that has to build up the oil pressure and then it pops open and then the noise goes away. And it can also be related to a variable valve timing problem where the gear assembly for the VVT has to warm up and it rattles until it does and the oil pressure builds up
So if i get a new belt tensioner the problem should theoretically go away or is it a manufacterer's defect? Also is this an issue in the long run?
No. You have a timing chain, not a timing belt.
No i don't, i have a belt. It's an 06 v6, not a 4 cylinder