Whelp, unfortunately, that didn't take long...
The guy that bought my turbo yellow Miata blew the Motor a little over a week ago. I was waiting until he pulled and dismantled the motor until I said something since we really didn’t know what was wrong. Considering it was smoking like a chimney, we had a pretty good idea however.
The trouble started when it suddenly died on the highway for no apparent reason. Not able to get it started, he called me for advice and finally for a tow. He calls me back a few minutes later and tells me he got it running but it won’t idle. It seems to run fine if the rpm’s are kept up so he tells me he’s going to limp it back to his house. I mentioned that I would probably go ahead and wait for the tow but he seems confident it is running fine as long as the rpm’s don’t get too low. All I can say is: “Take it easy!”
After some fiddling around with the car and a few phones calls back and forth, he finally discovers the #4 terminal on the coil has a bunch of insulation worn away and it is occasionally arcing off the firewall. This is a relatively common problem with a high-mileage coil so nothing seems out of the ordinary-- yet…
He picked up a used coil the next day, installed it and drove into work. He walks into our area (yes, I work with him and our desks are literally less than 10feet apart!) shaking his head and says he just managed to kill all the mosquitoes in the area. I didn’t have the heart to tell him it’s not mosquito season yet but we go down to the parking lot and check out the car anyway. While the car seems totally normal at idle, anytime he gets on the gas smoke comes pouring out of the exhaust. At this point he tells me that he never got past 8lbs of boost when the car was misfiring with the bad coil. 8lbs!?!
Not exactly my idea of taking it easy! Anyway, we speculate that he broke a piston ring in cylinder #4 (where the coil was bad) when the car was misfiring under boost.
After taking the head off the motor, it was pretty obvious what had happened. The piston in the #4 cylinder had a piece missing from the edge of it about the size of my thumb. My entire thumb!
You could plainly see the ring underneath which ironically looked to be in very good shape. Where the stray piece of piston went is anybody’s guess at this point. We carefully inspected the turbo and there doesn’t seem to be any signs of shaft play or blade damage. How it got through there without breaking something else is beyond me! He will be separating the downpipe from the cat to see if maybe the missing piece is laying against the cat honeycomb. If it’s not there, it must be back on the highway between Greensboro and Hickory. If anybody comes across it, please let us know…
What could have been a $50 coil pack fix turned into a god-knows-how-much-money engine rebuild. He is still debating weather to rebuild the current motor with new stock stuff, build the current motor with stronger pistons and rods (big $$$), get a junkyard motor or some combination of the 3.
On the bright side, the rest of the internals look great and the motor was virtually carbon free. I guess those Italian tune-ups really did the trick!
Jim
- who is considering moving his desk to the other side of the building...
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