Hi there. I have a 99 Civic LX, stock d16y7 with 180k miles. Recently the car has been sounding extra noisy during idle and acceleration. Typically when I used to start the car, it would have a little engine noise that would resolve as the engine heated. Now it doesn't seem to go away unless I've been driving for a good 15 to 20 minutes or so. It almost sounds like the engine is running a little dry, as if there isn't enough oil, if that makes sense. It sounds like a knocking sound that increases in speed and intensity as I rev the engine.

I've owned the car since 120k miles. I did a timing belt / water pump / all belt replacement at 160k miles. During that time, I redid the valve lash at that time and noticed that one of the lock screws was seized completely, though the car made no odd noises or anything. At 165k I completely replace the whole rocker arm that had the seized lock nut, which is around the time the new noise began. I have since rechecked the lash twice and everything is at spec per manual. I've changed the oil 2-3 times since with no improvement. I have checked the timing with a timing light a couple times and everything is normal.

When I replaced the rocker arm, I marked the timing belt and gear to make sure I didn't skip a tooth. That said, might I have messed up the timing? Could this be a failing oil pump that is not adequately circulating oil? When I did my timing belt, I noticed one of the engine mounts has rotted, torn rubbed... Could this be it?

The car drives fine and there's no issues with horse power. I'm just worried that I'm causing damage to the engine. Any suggestions would be amazing. I'm hoping to get another 100k out of this sucker.

 

If the car drives fine then you're fine on timing. Honda engines are sensitive when it comes to the timing so if you were off one tooth. Your car would start but immediately die. Or it would have a really really rough idle. The oil pumps don't typically go bad on Hondas. Not saying they can't go bad I'm just saying they don't typically go bad. If you redid lash on the valves and if you did it correctly I don't think that would do anything. Did you do it correctly? If you know 100% that you did it correctly then I would probably rule that out. My next question is what viscosity of oil are you using.? Because the wrong viscosity of oil if it's too thick or too thin could probably cause that.

 

Also to add on to what I said. The reason why oil viscosity is so important. Because there's two scenarios that can occur. #1 the oil can be thin to lubricate certain parts of the engine such as the valve . Or it can be too thick so it takes even longer for the oil to reach certain parts of the engine like the valves. So just remember the first number stands for the viscosity of the oil in winter time. Or on cold start ups. The second number stands for the viscosity or thickness of the oil at operating temperature. So for an example you've got 5w30 vs 10w30. At startup on a cold morning the 10w is going to be thicker than the 5w. But at operating temperature they're the same thickness or viscosity. So putting the right oil viscosity plays a very crucial critical part to an engines longevity.