Hey all, I've been searching and can't find any threads describing or showing the issue I have. I have a 1990 Miata with the mkturbo kit on it and recently got retuned on the dyno a few days ago, and as I was driving the next day I noticed a rattling noise coming from the front of the engine, I can hear it more under the car. It sounds like when a vacuum cleaner sucks up a rock and it's just rattling around, but it only happens above 2000rpms, not at idle, and it happens in gear and neutral as well. I can post a video as well, I'm thinking maybe a pulley bearing? It not making the noise below 2000 doesn't make me think it's a rod or anything, but I could be wrong. All fluid levels are good, spark plugs are brand new as well and gapped to .025. Any info or ideas would be great! https://youtu.be/MaI4cn3sTfQ?si=89OBTSJwEQTljFAI

 

Gotta get in there with a long screwdriver or mechanic stethoscope, have someone hold the throttle and press the tip to different parts and hold to your ear. Should be able to narrow it down pretty quickly. Don’t get sucked in the belts.

Had some random stuff happen to me in the past, like when one of the case bolts for my alternator came loose, and was striking the rotor, which made a similar noise.

you can also remove the accessory belts and run for enough time to see if the noise goes away..

you might have to remove the plastic timing covers to properly diagnose.

 

I had a similar issue many years ago. I searched and searched but could not find the cause. I was looking deep into everything, and it was right in front of me. Turns out it was the water pump pulley bolts. Check everything on the front of the engine before ripping stuff apart. Good luck

 

About 100 miles after I put together my built motor I had a terrible rattle pulling into the shop one day. It ended up being the cam gears (both of them) had worked their way loose and were rattling around.

Hopefully it's something simple, and silly, like that.

 

On my mk kit, the v band sometimes loosens and the downpipe will rattle against the frame momentarily. Make sure yours is pushed as far towards the trans as it will go.

 

Same thing here, I was about to start pulling the motor when I found that some idiot never tightened the pulley bolts.