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Discussion Starter · #1 ·
Just wondering what would be the cause (or causes) of a puff of bluish smoke upon ignition. Sometimes it is most noticeable first thing in the morning leaving a cloud, but most times it is just a little puff. No smoke is noticeable while driving.
 

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The engine is just burning oil. The piston rings are probably worn down and letting a bit of oil slip by and burning it in the combustion chamber.
 

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Just wondering what would be the cause (or causes) of a puff of bluish smoke upon ignition. Sometimes it is most noticeable first thing in the morning leaving a cloud, but most times it is just a little puff. No smoke is noticeable while driving.
Could be what talon said. In my experience this has been caused by worn valve seals (not sure if the Mazda has them though).
 

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Discussion Starter · #5 ·
The engine is just burning oil. The piston rings are probably worn down and letting a bit of oil slip by and burning it in the combustion chamber.
Yes I seem to need to top up the oil from time to time. More on short trips than long. But I don't feel as if I have lost any power. Thank you.
 

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Discussion Starter · #6 ·
More likely a leaking valve cover gasket leaking through the spark plugs ever so slightly (not enough to short the coils) or bad PCV leaking oil into the intake etc.
The valve cover gasket was supposedly done a couple of services ago (230,000 k service) but then so were the spark plugs which created a lot of problems. When taken to another mechanic was told "The spark plugs look like they have been in a long time" So now wondering if the gasket was actually done.
Will speak to the new mechanic regarding the suggestions offered. Thank you
 

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Discussion Starter · #7 ·
Could be what talon said. In my experience this has been caused by worn valve seals (not sure if the Mazda has them though).
Just done a quick search and find 'valve stem seals' for the Mazda. The new mechanic hasn't mentioned anything yet about any issues regarding seals or anything... yet. He has only had it once, replaced a leaking oil (?) switch and that that the auto needs servicing next visit. When I see him he gives me a half hour educational lecture on what he has done and why. That gives me a lot of confidence in what sort of job I can expect from him. That and what I learn from all you talented guys. Thank you.
 

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Have a friend follow you, coast down a hill for a while fully off throttle. If they see a puff of smoke once you get back on the gas after coasting down the hill, that's a pretty strong indicator of oil getting in past the valve seals.
 

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Have a friend follow you, coast down a hill for a while fully off throttle. If they see a puff of smoke once you get back on the gas after coasting down the hill, that's a pretty strong indicator of oil getting in past the valve seals.
That would be the indicator.
OP could try a high mileage formula to offset.
 

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Discussion Starter · #10 ·
Have a friend follow you, coast down a hill for a while fully off throttle. If they see a puff of smoke once you get back on the gas after coasting down the hill, that's a pretty strong indicator of oil getting in past the valve seals.
I did have someone follow me (normal driving) and they couldn't see anything.
Another person told me they saw a puff of blue smoke when I drove off.
I will try your coasting down a hill suggestion as never tried it that way.
Thank you.
 

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I did have someone follow me (normal driving) and they couldn't see anything.
Another person told me they saw a puff of blue smoke when I drove off.
I will try your coasting down a hill suggestion as never tried it that way.
Thank you.
You want to be engine braking for that to work effectively. Strong manifold vacuum is what you are trying to achieve.
If you have a manual trans then just lift throttle in a numerically high gear. If it is an automatic transmission, then put it in manual mode in an equally high gear numerically and lift throttle just the same.
The longer the off pedal deceleration, the more oil will be pulled past the valve guides into the combustion chamber for your smoke screen effect.
 

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Discussion Starter · #12 ·
You want to be engine braking for that to work effectively. Strong manifold vacuum is what you are trying to achieve.
If you have a manual trans then just lift throttle in a numerically high gear. If it is an automatic transmission, then put it in manual mode in an equally high gear numerically and lift throttle just the same.
The longer the off pedal deceleration, the more oil will be pulled past the valve guides into the combustion chamber for your smoke screen effect.
Okay so it's oil getting sucked into chamber... and gets blown out.
Which would explain why at start-up after being parked overnight. Just yesterday I was parked for 6 hours and after about 10 metres (slow driving) did a u-turn and accelerated a tad heavier than normal (5000 revs) leaving behind a cloud of blue smoke. But today, cruising on the freeway in cruise control set at 110 ks there was no smoke with gear change to climb a hill.
Thanks, I will try the engine breaking thing.
 

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Could be what talon said. In my experience this has been caused by worn valve seals (not sure if the Mazda has them though).
A blue puff out the back after sitting over night usually indicates valve seals. High mileage engines can have lots of sludge on top of the head if oil changes were not performed as suggested. Depending on the head design, sludge can clog oil drain back passages trapping oil on top of the head to be sucked past the valve guides.
It's been a long time since I dealt with this issue. If valve seals are the problem, they may be able to be replaced with out removing cylinder head. The tool I bought long ago resembles a steel alligator mouth with lever on top used to compress the valve spring with it's jaws. The design fits into the bottom of the spring where it meets the head and on top of the spring retainer. The lever when folded over compresses the spring so the keepers can be removed, lift off the spring and gain access to the valve seal. I used this tool about three times many years ago and saved me much time and labor not having to remove the heads, not for valve seals anyway.
To do this operation a compressor is necessary to keep the valves closed while removing the spring keepers and then reinstall them. Before I got a professional compressor I used a compressor powered by the cars cigar lighter and adapted it to make it work the first time I did this job on our 1983 Ford Escort.
If this job is attempted by a novice and it can be done, it is wise to bring each piston to TDC as an precaution in case a valve drops down, it can then be pulled back up by it's valve stem. TDC is easy, bump starter and look down plug hole and watch piston to come up to top of it's stroke.
For that first and subsequent valve seal jobs I made an adaptor by busting out the porcelain top of a spark plug and welding a male air chuck fitting onto the plugs base so compressed air can be applied to keep the valves closed while replacing the seals. Valves need to be tightly closed to be able to remove the valve keepers and then reinstall them.
The air hose pictured should be able to fit a male air chuck to it, probably a better set up then my adapter since plugs are in a deep well in the Mazda engine. The tool below is only an example of a spring compressor, it much different then one I have but the idea is the same.
242772
242773
 

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Discussion Starter · #16 ·
This is something that I will leave to my mechanic - now that I have found a good one.
I did the 'brake test' and didn't need the one following me... I saw the blue cloud lingering in my mirrors.

You guys are brilliant so can only thank you for your advice and suggestions.

I have a Mazda 2 and the 6 wagon and prefer the wagon. It is so similar to my Falcon XP wagon which I wish I had never sold.

The only modification I have made is replace the 6 stack CD player with a 10" touch screen which actually blends in quite well and looks 'original'. Tow a Teardrop (squareback) caravan some weekends.

What with work and weekends away, some weeks I end up doing 1000 kilometres on those weeks.
The only issues I have had is a franchise service centre doing absolutely crap service on MYcar due to fitting broken and inferior sparkplugs and trying to fix it without checking the sparkplugs they supposedly had put it (long long story). New mechanic fixed it pronto - NGK sparkplugs. Oh yeah, and this smoke issue.

Thanks guys, you are all brilliant.
 

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Discussion Starter · #18 ·
@jb86796 excellent write up. I think you nailed the remedy for the overnight oil puff perfectly. I did the same job with heads on as well.
It looks like valve guides, based on a subsequent post from the OP.
I agree, a brilliant explanation.
I think my mechanic will be impressed, but then I wouldn't be surprised if he tells me first. Each time he does a service he gives me a 209 minute talk on what he has done and how, where, when and who. :giggle:
 
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