Mechanics

Blue Smoke from Exhaust Pipe

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Step by step repair guide on how to troubleshoot and repair blue smoke from the vehicles tail pipe. This article pertains to all cars.

Difficulty Scale: 4 of 10

Tools and Supplies Needed

  • Flashlight
  • Socket set
  • Wrench Set
  • Screw Driver Set
  • Protective eyewear and clothing
Before beginning, park the car on level ground with the parking brake set.


Blue Smoke from Exhaust Tail Pipe

Step 1 - Some engine's have small oil drain back holes in the cylinder head, these holes allow the engine's oil to drain back into the oil pan. If these drain back holes become plugged with sludge it can cause motor oil to fill the valve cover up, causing oil to seep down into the intake and exhaust valves and into the combustion chamber. To repair this problem remove the valve cover and clean debris from the drain back holes, reassemble and recheck (Note: After the repair you must wait 2 to 4 days before the remainder of oil on the valve stems to be removed.)

Step 2 - Valve stem seals control oil from entering the combustions chamber. If these seals have worn out blue smoke will result. To repair this problem replacing the valve stem seals is necessary.

Step 3 - If step one and two check out the only additional way for the engine to produce blue smoke is through the piston rings. If this is the case the engine is worn out and replacement is needed. To confirm this diagnosis remove all spark plugs and inspect, if all plugs have oil on them the confirmation has been achieved, if a single plug is fouled then only that cylinder needs to be fixed. Visit - Piston ring replacement

Helpful Information

Blue smoke is caused from several specific conditions inside the engine. This guide will help you determine what the problem is so it can be corrected. Blue smoke appears mostly at morning start up's because oil from the vehicle's engine is mixing with the gas inside the engine's combustion chambers, then burns together with the fuel from the injectors while the engine is running. This can result in an expensive repair, but not always. The more expensive, and usually terminal reason for blue smoke is the piston rings of the engine have worn out which is allowing engine oil to pass into the combustion chamber while the engine in running. In this case the engine is worn out and needs to be replaced.

Best Practices

  • Its important to note that if you decide to repair the engine, often you are looking at hourly repair rates plus parts and machine work. This is quite costly depending on the age of the engine, this may well not be worth the expense of the repair. If you are highly fond of the vehicle and intend to keep it, there are definitely times when a new or rebuilt engine is a more desirable option. The best options on a new or rebuilt engine maybe obtained by the dealer; surprisingly dealer cost for the engine (engine only, not labor to install) is close to what a engine rebuild can cost independently.
     
  • Poorly maintained engines are much more prone to problems such as smoking. The excessive friction leads to catastrophic engine failure. Preventative maintenance is cheap insurance to ensure that a vehicle runs as smooth as possible for many miles to come.
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AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2014-10-23)