Spark plug shot out

Tiny
TRYON
  • MEMBER
  • 2007 MINI COOPER S
  • 1.6L
  • 4 CYL
  • 2WD
  • MANUAL
  • 146,000 MILES
Put marvels mystery oil in the spark plug holes. Did not tighten the spark plug enough but they were not hooked up. Tried to start the car plug came with a loud bang. Threads are fine but the plug was bent a little at the business end. Going to start it up in the morning and replace the plugs. Is there anything I need to look out for? Basically is there a possibility I fried my engine?
Saturday, June 2nd, 2018 AT 6:20 PM

1 Reply

Tiny
STEVE W.
  • MECHANIC
  • 14,159 POSTS
It is possible you did damage if the plug was forced out by having too much oil in the cylinder and it hydraulic locked and blew the plug out. Was there a lot of oil blown out as well? How much did you put into the cylinders and why? Was it only the one plug? How far was the plug installed? If it was in there to the seat but not tight it takes a lot of pressure to blow one out and was much more likely to have done damage.

To test if there was damage would take some specific testing. Namely a leak down test and using a CC test to determine if the piston is farther down in the cylinder. You may be able to see it if you ran a compression test with the engine running but even then it would be hard.

If it has been damaged but still turns over freely I would install the plugs and see what it does. Then see if you can do a running compression test and see what numbers you get.
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Saturday, June 2nd, 2018 AT 9:15 PM

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