update:
I think it's just something with the first spark plug area closest to you while standing in front of the car. The rubber was vibrating and when I push down and can feel something tapping back. In a certain position the sound disappears.

Video of me holding down the spark plug. I'll upload other ones later if needed.

YouTube - MVI 0981



original post:
YouTube - MVI 0974




It's louder than the lifter tick on my old miata.

110k mile engine on the car I bought.


admin edit:

 

Check your crank pulley and see if it is wobblying. If it is check your main crank bolt. Mine had come loose and was making a similar sound but much louder.

 

Had the car sat any? I had a lifter stuck that loud once. Try slick 50. Could be a wristpin, rod. etc.

 

Sounds like a rod to me.

 

I gotta agree with a rod too.

Rev the engine higher and snap the throttle closed, that makes it even more evident.

 

I'm not sure how to check the crank pulley. I've never done anything but change oils.

The car sat for a week before the video was taken. It had the noise when I bought it but I wrote it off as lifter tick. I let it warm up and idle and it would go through the noise then a bit louder and back again(repeat).

I'll try revving it louder next time.

Thanks!

 

Start the engine, stand perpendicular to the engine and watch the crank pully. If you see a wobble, then its fubared.

 

can you move the camera around, faster next time?

 

umm.....how's the oil level look?

 

Oil level was on the full line and still golden in color when i bought it.
I'll try to leave the camera in front of the engine next time I start it.

Thanks.

 

Mine had a collapsed lifter when I got it, and sounded much the same. Loud as hell. It had been sitting for a long time. After several DAYS of driving it finally pumped up and quit.

Don't use Slick 50. That's not what it's for. And it doesn't do anything useful anyway.

The way to better determine if it might be a rod knock is to put the car under a load and listen to it. If it is a deeper sound that seems to be exacerbated by being under a load, then it may be a rod. If it sounds about the same at the same rpms regardless of load, than it may be in the valvetrain (lifters).

Try running it in third or fourth gear at about 3k rpms. Add and remove throttle and see if it increases in intensity (loudness) when throttle is added and gets quieter when released. If yes, it may be a rod.

If no, and it appears to be a lifter, you can just live with it a while and the fresh oil may cause it to pump up soon. If you wanted to add a quart of automatic transmission fluid to the crankcase and let it idle for a half hour (DO NOT DRIVE IT), then change the oil with fresh oil and a filter, that is a known way to encourage a collapsed lifter to unstick (ATF is thinner and has detergents that will assist in the process). That trick has been around for over 30 years. Or, like I said, be patient.

Best of luck to you.

 

BTW - Nice camera work. How many years have you had epilepsy?

 

I think it's just something with the first spark plug area closest to you while standing in front of the car. The rubber was vibrating and when I push down and can feel something tapping back. In a certain position the sound disappears.

Video of me holding down the spark plug. I'll upload other ones later if needed.

YouTube - MVI 0981

 

your **** is crazy fucked, yo.

In for helicoil action.

 

I had a situation where I thought I had rod knock (spun a bearing) too. It ended up being a loose spark plug. Here's the video of it.

YouTube - b18c knock

I was told you can remove each spark plug wire, one at a time to isolate the problem. Otherwise you can pull the oil pan to check the bearings which is not really feasible for miata owners.

 

Will it gently tighten, or is it stripped off inside the head?

I've never had one run with a loose plug before. Missing, yes, loose, no. Sorry I missed that before.

 

I had a 240sux with a loose plug once. I drove for a week thinking the motor was about to let loose before it finally came out and put a backwards dent in the hood.

 

So whats the question? Looks like you either have stripped threads at the spark plug, or its not tight... helicoil time?

 

Now I have to google helicoil.
I had no tools.
update later.