Jeep is misfiring and blows gas and blue smoke out of tail pipe and idles rough

Tiny
MXMUDMONSTER
  • MEMBER
  • 2001 JEEP CHEROKEE
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 152,000 MILES
When I start the jeep It take a little to crank it. Then it idles really rough. When I accelerate it blows blue smoke and gas out of the tail pipe. Cylinder 2 and 3 plugs are wet.
Monday, August 4th, 2014 AT 4:28 PM

1 Reply

Tiny
FREEMBA
  • MECHANIC
  • 1,152 POSTS
The blue smoke indicates that the engine is burn oil. Since cylinders 2 and 3 are wet these are likely the bad cylinders.
Oil is entering the cylinder by either getting past the valve stem seals or by getting past the piston rings. If the valve seals are the problem the cylinder head does not have to be removed to replace them (saves money). If the rings are the problem, then you need and engine overhaul, much more expensive.

You need to perform a compression test an all cylinder's (especially #2 &3). If they have lower compression than the rest, perform a "wet compression test" on them. That means that you will squirt about a teaspoon of oil into the cylinder and retest the compression. If it increase now, then the piston rings are bad. If it stays the same then the problem is likely the valve stem seals.

According to the info you've given, I believe that the piston rings are the culprit.
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Monday, August 4th, 2014 AT 4:43 PM

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