loud knocking at idle and while revving
 

My friend's 95 started knocking under load and now knocks all the time. Head and valve train look ok. An inspection camera didn't find anything in the combustion chamber. Compression is 200/180/150/150. Is this a bottom end problem like a bent rod or spun rod bearing?

Engine is stock, no turbo, but it has 200k miles and unknown history from previous owners.

Bearing. It's done.

yup. time to yank that sucker

www.car-part.com

Or rebuild it and force feed it.

just use 75w-90 oil.

Ok, that's what we thought. New engine is already being sourced. My ls1 which had 1 spun bearing with only small amount of wear didn't sound nearly this bad, but would barely idle when it was pulled. This thing drove 50+ miles and still idles/revs all while clanking. :rofl:

We do have a 70k mile vvt longblock for sale just fyi;)

Miata engines are some of the loudest, most baffling, and yet toughest engines I've ever seen.

I've seen a 1.6 lose most of it's coolant (Radiator neck leak), get ran for ~80 miles, leak fixed and filled back up...and it was fine.

Just keep running it, see how long it lasts. Not on a track though. You'll ruin the day if you oil down the track.

He was driving up to the corkscrew at Laguna when it happened so it's already seen some track time while knocking... While it might be fun to blow it up and possibly add a hole to side of the block I'd rather just swap it out now and open it up.

Rebuild it for a shelf spare. Ebay rebuild kits are cheep, if you wanna cost effective diy project.

We pulled the motor today. Drained the oil... all 0.5 quart that was left. :facepalm: Spent most of the day swapping parts and redoing all the belts and seals on the new motor. If anyone has an extra carfax I'd appreciate if you can lookup the new motor in exchange for some $$$: JM1NA3536S0610298

Give this a shot:

yeah, cause clicking a .ZIP file from a member with two posts is totally a good idea.

afaik .zip files are pretty innocuous (maybe I'm wrong)? I figured the .xps format wasn't supported by the forum upload software.

@orion4096
Can't PM yet, so I'll reply here:
No worries, I had the Carfax left over from car shopping last weekend. Don't worry about paying, it was going to go to waste anyways.

Swapped the motor last weekend and it looks to be running good. Haven't had a chance to pull apart the old one, but we did cut open the filter. I think there's more than 4 bearings worth of metal in it:

Attachment 185956

Horrible... you should collect up what you can with a magnet & weigh it. :rofl:

What's left of the #4 rod bearing next to another half that looked fine. Nothing else was obviously broken from a quick inspection.

Attachment 185952