BLUE SMOKE

  • Tiny
  • shaina.marie
  • 2003 Mazda Protege
  • 13,800 miles

I have a 2003 Mazda Protege 5. Every time I start it up after about 6-8 hours, blue smoke comes out the exhaust. It burns through about 2 quarts of oil a week. We have replaced the PCV valve twice, put on a whole new head with all new valve seals and everything, new spark plugs, new head gasket, and checked the compression of piston rings. Compression is fine. We found that oil was in the PCV valve and draining into the intake manifold. Took out spark plugs and took a flashlight to look down the cylinders. There is a pool of oil on top the pistons in each of the 4 cylinders. Please help! What else could it be?

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Monday, December 12th, 2011 AT 12:44 AM

11 Answers

  • Tiny
  • rivermikerat
  • Expert
  • 6,174 posts

Bad valve seals.

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Monday, December 12th, 2011 AT 12:54 AM
  • Tiny
  • shaina.marie
  • Member

We already replaced the valve seals. The new head that we put on had all new valve seals and everything.

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Monday, December 12th, 2011 AT 1:03 AM
  • Tiny
  • rivermikerat
  • Expert
  • 6,174 posts

Oil accumulating in the cylinders can have only three causes: 1: Bad valve seals.
2: Blown head gasket.
3: Bad rings.
Ok. 4 causes.
4: Cracked head or block.

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Monday, December 12th, 2011 AT 1:10 AM
  • Tiny
  • shaina.marie
  • Member

Well we replaced the valve seals and the head gasket. We did a compression test for the rings and they are all fine and bought a brand new head. Even after replacing all of that it still burns oil. So it sounds like it must be a cracked block.

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Monday, December 12th, 2011 AT 1:19 AM
  • Tiny
  • shaina.marie
  • Member

How much would the block typically cost? How much labor are we talking to replace the it?

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Monday, December 12th, 2011 AT 1:25 AM
  • Tiny
  • rivermikerat
  • Expert
  • 6,174 posts

That would be my thought.

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Monday, December 12th, 2011 AT 1:31 AM
  • Tiny
  • rivermikerat
  • Expert
  • 6,174 posts

I couldn't tell you. It varies by area, age, mileage, and displacement.

Your best bet is to find a used complete motor or block, long or short. Since you have a new head already, I would go with the short block, which doesn't come with the head.

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Monday, December 12th, 2011 AT 1:40 AM
  • Tiny
  • shaina.marie
  • Member

I know some of the symptoms of a cracked block and we don't seem to have any of those symptoms of than the smoke from the exhaust. The antifreeze is clean (no oil in it) and on the contrary the oil does not look milky like it would if there were antifreeze in it. The engine is running fine and is not overheating. Is there still a possibility it's a cracked block even with the absence of those symptoms?

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Monday, December 12th, 2011 AT 1:45 AM
  • Tiny
  • rivermikerat
  • Expert
  • 6,174 posts

Yes. Oil galleries run alongside the cylinder bores. A crack between the gallery and bore wouldn't mix oil and water.

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Monday, December 12th, 2011 AT 2:18 AM
  • Tiny
  • shaina.marie
  • Member

Okay. I will look into that. Thank you very much for your help!

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Monday, December 12th, 2011 AT 7:29 AM

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