I have jag xj6 which sometimes gives out a blue smoke from exhaust when starting?

Question

This only happens occasionally and it is just a burst of blue smoke on starting the engine. The car does not burn oil, just this occasional puff of blue smoke.

Answer 1

its normal for a jag. the blue smoke isnt oil, its fuel. Jags have a cold start injector that kicks on during startup and since it isnt used all of the time, it gets a little sticky and can let out too much fuel. try regular injector cleaner in your gas. it should clean up.

Answer 2

My old Mundane-o did this after the mechanic was supposed to have reworked the head & valves following a cambelt failure. It's oil getting into the cylinder via the valve stem seals - if you've got high mileage, it's because they've baked and worn a little.
If it stops after a short while, once the engine warms up and the componants expand with heat, the seal between valve and valve stem guide contracts, making the seal air-tight once again. As the engine cools, everyting contracts a little, opening up the leak once again.

You need to get a decent mechanic to take a lok, but be warned - if they have to take the cylinder head off, it's gonna be expensive...

Answer 3

As a longtime Jag owner and a veteran of over 6 decades, the best solution is this: if it ain't broke, don't fix it. "Occasionally" is the key word. Assuming it is a 4.0 OHC 6 cylinder, reparing small problems when not ENTIRELY necessary, can easily lead to big problems. The cold start injector could be the cause, but it does no real harm short or long term. My suggestion is ignore it unless it becomes a constant smokescreen generator. Happy motoring.

Answer 4

Possibly a pin hole head gasket leak causing oil to pool from the oil galeries to the top of one cylinder. That is why it is only noticable when starting. Head gaskets seperate the oil and water galleries inside the head and block. Nothing to panic about until a constant blue or white smoke is present or oil consumtion becomes measurable. White smoke being indicative of water leaking into cylinders thus producing steam.

Answer 5

sounds like just a little drop of oil is in the pods, it doesnt take alot to create a puff of smoke on start up.
I dont know jag engines well but i would start at looking at the value seats.

Answer 6

KWB hit it on the head. One more thing to note. I'm not sure how these engines are installed, but with Chevy V8's, the rear two plugs fouled with oil after a little while.

Reason being, the engine is tilted back a bit, and more oil sat on the back two cylinder's valve seals.

Answer 7

valve seals are leaking.

what happen is when you turn off your engine oil leak down to top of the piston then when turn your engine back on, the amount of oil that leaked down is burn up inside combustion chamber and blue smoke come out of the tail pipe.

Answer 8

The first answer was partially correct, but it's not necessarily the guides.........probably worn valve seals, that allow the oil to drain into the combustion chamber when the car is sitting, and not running. When you first crank it up, its burning that little bit of oil that seeps into the cylinder........It is somewhat of a major repair, but the heads don't have to come off........just labor intensive.

Answer 9

billyboy is the only one here that is correct it is the fuel run some injector cleaner through it you will be fine if it was oil the smoke would be white carbon build up the smoke is black fuel the smoke is blue

Answer 10

Its the carbon deposits from the cylinder. Or the spark plug needs to be replace and timing adjusted.