Unbelievable! New engine runs well at first key .. er, button, but clatters with two distinct 'notes', but mainly like a coffee can full of quarter-twenty nuts. Plugs are all textbook clean after coming up to temp, ~140 pounds compression in each cylinder within a percent, again no sludge and the cams look clean except for the teeniest bit condensation rust on the #4 intake lobe. I testify no errors in the install and proper 0/20 oil fill.

Sounds like an old 327 Chevy with very loose valve lash and an exhaust manifold leak. First thought on one tinny note was perhaps a loose heat shield, but nope.

In for two grand plus tax, and a hundred for fluids and gaskets. Boss man asked my advice, even after my advice was to go for a boneyard pull. I think it should go to Mazda for a second opinion before pulling the plant and making Karen face at the seller. What say you?

My spidey senses .. Occam's razor, and generally low self esteem as the gal's don't look at me anymore say more likely I boned the job rather than bought a crap engine from a reputable local seller .. but this has to be my 400th swap from Detroit 6V-71 to GM M platforms. not like I forgot the converter nuts.

 

An interesting update and close to this thread ..

The swapped engine is (and was) fine. No idea why it was so noisy originally, but it settled down and sounded good internally .. but still wouldn't run right.

I put another full day into it, no codes unless I forced them, just wouldn't fly straight. felt like I was back in 1985 and the Weber 32 carb main metering on my Renault 5 had a bit of shmutz in it.

Out of tricks and brains, it went to Mazda. Oh the shame .. seriously. this is my first beat down since I outgrew pimples, playboy, and the small block Chevy.

Well .. 'myths' my old wrinkled hiney .. Turns out to be two spark plugs - even though they looked good and no misfire codes.

Can't explain it - but there it is. I'd call bull myself, but I'm not yet crazy enough to believe the Mazda people simply reset the cyberdyne module designed to make shade trees look like fools.