Good morning! I come to you folks asking for your help in diagnosing an issue I'm having with a recently acquired 1998 Civic EX that needs some TLC.

I just replaced the alternator as I thought it was the source of the harsh grinding noise I was hearing, thought it sounded like a bad bearing. Anyway, that didn't do it. Now I'm thinking either water pump, timing tensioner, or maaaybe valve train noise (I plan to do the adjustment shortly anyway). Sounds like its coming from right under the timing cover. Check out the video and let me know what you guys think. Thanks!

 

A mechanics stethoscope will be a great help isolating the noise. A dowel or a long screwdriver can be used instead but isn't as efficient in many ways.

From the video, we cannot tell if it's top end or bottom end but that sure did sound like a real nasty knock.

It also looked like you had all the belts off which rules out everything except engine and transmission. I know you had the alternator belt on but you also replaced it for no change.

 

Yeah it's definitely not the alternator at this point. I'll try to stop by the auto parts store for a stethoscope on my way back from work. We'll see how it goes. Praying it's not critical, but it certainly sounds brutal.

 

Removing the upper timing cover is simple (though you will need to loosen or remove the valve cover also).

It doesn't sound like rod knock fortunately. Rod knock will get louder when you put in gear and drive. Most other mechanical noises won't.

A timing belt job and valve adjustment are standard procedure on any newly acquired Civic, but first you need to be sure the engine is OK before spending money.

 

Or a long skinny flathead screwdriver.

 

Thanks for the suggestions guys. I plan on doing the timing belt (water pump/tensioner) and valve adjustment once I get some more warm weather - the struggle of no garage in Ohio. It really didn't sound like rod knock to me either so that's a bit reassuring, and seems to get quieter (or at least stay the same volume) when accelerating and in gear. Has IAC issues with p0505 CEL fwiw but not worried about that for now.