Blue Smoke Issue

[Rick4570]

One day when my Jeep had around 3500 miles, upon start up, cold engine, a huge plume of blue smoke came out of the exhaust. Lasted a few seconds before clearing up. I kept an eye on it, didn't happen again until.....2 years and 16,500 miles later. Did it again. I'm talking a huge bellow of blue smoke. Enough that it was embarrassing because everyone at work thought my engine was on fire! That was a month ago and it hasn't happened again.

The local mechanic said maybe when the engine was turned off, it just so happened to have stopped when one of the valves was open and a little bit of oil dripped into the combustion chamber.

Weird situation. I guess if it happens every 16,500 miles i can live with it!

Anyone else ever had an issue like this with the 3.6?

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[mwilk012]

How much oil are you losing between oil changes?

Do you have any modifications to the engine?

 

[azwjowner]

The local mechanic said maybe when the engine was turned off, it just so happened to have stopped when one of the valves was open and a little bit of oil dripped into the combustion chamber.

I've had smoke on startup exactly twice in 7000 miles. Once I had just completed a steep hill climb and turned the engine off. Given that the 3.6 is known to smoke on angles, I figure it was left over.

The other was when I let the vehicle stall (manual) and didn't turn it on until a few days later. A little smoke came out. My guess is that the stall did exactly what your mechanic theorizes. Never had it happen when killing the engine with the push button.

 

[mwilk012]

I've had smoke on startup exactly twice in 7000 miles. Once I had just completed a steep hill climb and turned the engine off. Given that the 3.6 is known to smoke on angles, I figure it was left over.

The other was when I let the vehicle stall (manual) and didn't turn it on until a few days later. A little smoke came out. My guess is that the stall did exactly what your mechanic theorizes. Never had it happen when killing the engine with the push button.

There are always some valves open on both intake and exhaust. If your valve seals are leaking so bad that you look like an old worn out Chevy on startup, you have issues that need looked at.

 

[m3reno]

It looks like your still under warranty I would bring it in and have them look and document this issue. mwilk012 what are some ways to check for leaky valves.? Those issues usually happen on higher mileage vehicles.

 

[Jrocket]

There is definitely something going on, you should take it in and get it documented. Have you noticed if it smokes when you leave it sitting for prolonged periods. Also if you daily the car you might not notice the blue smoke since you don't let the oil puddle in the engine.

 

[Rick4570]

How much oil are you losing between oil changes?

Do you have any modifications to the engine?

No oil loss between changes (so if it is using, it is minimal).

Factory stock

 

[Rick4570]

There is definitely something going on, you should take it in and get it documented. Have you noticed if it smokes when you leave it sitting for prolonged periods. Also if you daily the car you might not notice the blue smoke since you don't let the oil puddle in the engine.

I left for two weeks during Christmas, came back and remote started it while standing by the tailpipe, zero smoke.

 

[tomk62]

ChatGPT sez ...

Experiencing a large plume of blue smoke coming from the exhaust on startup, especially after the vehicle has been sitting for a while, can indeed be concerning. While it's difficult to diagnose the exact cause without a thorough inspection, there are a few common reasons why this might occur:

1. Valve seals: Worn or damaged valve seals can allow oil to leak into the combustion chamber when the engine is off, resulting in a large puff of blue smoke on startup. This could explain why the issue is intermittent and occurs after the vehicle has been sitting for some time.
2. Piston rings: If the piston rings are worn or damaged, they may not properly seal the combustion chamber, allowing oil to enter and burn along with the fuel-air mixture. This can also result in blue smoke on startup.
3. PCV system: A malfunctioning Positive Crankcase Ventilation (PCV) system can cause excessive oil consumption and lead to oil being pulled into the combustion chamber, resulting in blue smoke on startup.
4. Cylinder head or gasket issues: Problems with the cylinder head or head gasket, such as leaks or cracks, can also allow oil to enter the combustion chamber, leading to blue smoke.

Considering that the issue has occurred twice, it's a good idea to have it inspected by a qualified mechanic or dealership technician. They can perform a thorough inspection to pinpoint the exact cause of the blue smoke and recommend any necessary repairs. If the vehicle is still under warranty, any necessary repairs should be covered.

While it's understandable to feel concerned about the issue, it's worth addressing to ensure the long-term health and reliability of your vehicle. Ignoring potential issues with oil consumption or engine internals could lead to more significant problems down the road.

 

[badge171]

For what it's worth , don't always assume its an oil issue . Check your coolant . Pressure test.

 

[Rick4570]

ChatGPT sez ...

Experiencing a large plume of blue smoke coming from the exhaust on startup, especially after the vehicle has been sitting for a while, can indeed be concerning. While it's difficult to diagnose the exact cause without a thorough inspection, there are a few common reasons why this might occur:

1. Valve seals: Worn or damaged valve seals can allow oil to leak into the combustion chamber when the engine is off, resulting in a large puff of blue smoke on startup. This could explain why the issue is intermittent and occurs after the vehicle has been sitting for some time.
2. Piston rings: If the piston rings are worn or damaged, they may not properly seal the combustion chamber, allowing oil to enter and burn along with the fuel-air mixture. This can also result in blue smoke on startup.
3. PCV system: A malfunctioning Positive Crankcase Ventilation (PCV) system can cause excessive oil consumption and lead to oil being pulled into the combustion chamber, resulting in blue smoke on startup.
4. Cylinder head or gasket issues: Problems with the cylinder head or head gasket, such as leaks or cracks, can also allow oil to enter the combustion chamber, leading to blue smoke.

Considering that the issue has occurred twice, it's a good idea to have it inspected by a qualified mechanic or dealership technician. They can perform a thorough inspection to pinpoint the exact cause of the blue smoke and recommend any necessary repairs. If the vehicle is still under warranty, any necessary repairs should be covered.

While it's understandable to feel concerned about the issue, it's worth addressing to ensure the long-term health and reliability of your vehicle. Ignoring potential issues with oil consumption or engine internals could lead to more significant problems down the road.

The mechanic at the dealership could not replicate the issue. With no visible oil usage, no visible coolant loss and the fact that it went 16,500 miles between issues, rules out most theories. He said to keep an eye on it. So every time I start it I I pay extra attention.

The inside of the tail pipe looks as clean as day one.

 

[Rick4570]

Maybe this is more commonplace than I thought!

(47) Occasional Smoke at Start Up??? | Jeep Wrangler Forums (JL / JLU) -- Rubicon, 4xe, 392, Sahara, Sport - JLwranglerforums.com

 

[Mgdstar]

I would look into the extended warranty at this point.

 

[mwilk012]

I wouldn’t lose any sleep over it. More likely the oil is pooling up in the intake from the pcv system and occasionally sucking a good slug of oil into the engine. It doesn’t take much to smoke, but the catalysts should be able to filter out a normal amount.

 

[Bandit59]

One day when my Jeep had around 3500 miles, upon start up, cold engine, a huge plume of blue smoke came out of the exhaust. Lasted a few seconds before clearing up. I kept an eye on it, didn't happen again until.....2 years and 16,500 miles later. Did it again. I'm talking a huge bellow of blue smoke. Enough that it was embarrassing because everyone at work thought my engine was on fire! That was a month ago and it hasn't happened again.

The local mechanic said maybe when the engine was turned off, it just so happened to have stopped when one of the valves was open and a little bit of oil dripped into the combustion chamber.

Weird situation. I guess if it happens every 16,500 miles i can live with it!

Anyone else ever had an issue like this with the 3.6?

Unless it happens more often I would not worry about it

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