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This is what it looks like. Got the piston & bent the rod & cap up like a pretzel. Happen on my 99 Miata.

Eeeek!!!!

Man, what a mess. I'm assuming the car stopped dead in it's tracks?

Ando wrote:Eeeek!!!!

Man, what a mess. I'm assuming the car stopped dead in it's tracks?

Was rolling down the interstate 40 here about 70mph. Heard a bang & pop clutch it & pop it out of gear & costed over to the side of the interstate with a dead engine. Hour later on the hook haveing it taken home.$$$ Was hoping it was the timming belt but she was locked up. Pulled the plugs & # 4 plug gap was hammer closed. So I pulled the head & saw what made the bang & pop.$$$$$$$

Is this the result of the dreaded #4 thrust bearing failure problem with the 99 model?

JBT wrote:Is this the result of the dreaded #4 thrust bearing failure problem with the 99 model?

I dont think so it had over 143,000 miles on it. I found one of the #4 rod bolt nuts in the bottom of the oil pan. Think it came loose & cause the crank bearing to spin an then the nut came all the way off. The thrust bearing wasnt beat up etc. The head - block & crank are ok.

You're really lucky it didn't ventilate the block!

I'd be checking the condition of the bore in #4 very closely though.

Benny wrote:You're really lucky it didn't ventilate the block!

I'd be checking the condition of the bore in #4 very closely though.

There was a small nick about a inch long in the bottom of cylinder where the rings dont go down that far. 4 or so up & down passes with a engine cylinder honer cleaned it up.

Thank goodness you can save it then.

Might be a very good excuse to bore it out a little.