This could explain the low power as well. However, post a recording of the knock because this may not be a bearing noise. Does it get faster when you accelerate?
You can drop the oil pan and look at the bearings but if you have metal through the engine then you are going to need to go through the whole engine because that metal most likely damaged a lot of bearing and the only way to know is to rebuild it.
I just would not want to see you go through all that trouble just to put it back together and it still make noise.
I would at least start with dropping the pan and seeing how much oil and what the crank bearings look like.
Post some pictures of the bearings if you can. Thanks
Wednesday, September 9th, 2020 AT 6:21 PM