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bw · Posted: Thu Aug 14, 2003 10:55 am Post subject: Smoke

Followed Tracee in the P4 up the dual carriageway this morning and noticed very very occassionally small puffs of dark smoke coming from the exhaust. Barely noticeable unless you're paranoid like me, but what might this be. Perhaps the oil is too thin and sneaking past the piston rings? Or maybe a gasket is blowing a little?

Perhaps this is normal/acceptable? This is at high speed by the way, probably 4 or 4.5k revs in 5th gear.

Should we be worried?

ChrisC · Alfa Sprint Joined: 13 Mar 2003 Posts: 152 Location: Frome

Probably just running a little rich - check it on an emissions machine.
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Gary UK · Posted: Thu Aug 14, 2003 8:17 pm Post subject:

I bet it is when you change gears that the smoke appears, this is normal for an older car so don't worry unless it's excessive.

The pressure in the engine suddenly increases dramatically when the clutch engages so oil is forced past the valve stem seals/piston rings and hence you get a puff of blue smoke.

Dreamracers · Posted: Sat Aug 16, 2003 10:20 pm Post subject:

Gary UK · Posted: Sat Aug 16, 2003 11:39 pm Post subject:

The boxer engine is good for not burning oil when the valve stem seals are worn because gravity is not forcing oil down into the cylinders like on a normal engine, BONUS!!

bw · Posted: Mon Aug 18, 2003 1:30 pm Post subject:

Thanks for the ideas guys. From what I can tell the smoke is more black than blue (indicating fuel problem?). It doesn't seem to be using any oil either.

I'm not sure exactly when the smoke is coming out (not being able to follow myself whilst driving Confused

). One thing I have noticed is a quiet sort of sucking noise briefly happens a couple of seconds after you let your foot off the gas sometimes, but don't know if it's related and is probably normal.

MOT is due soon so emissions will be check in a couple of weeks anyway.

Dave_NZ · Posted: Tue Aug 19, 2003 11:37 am Post subject: anythings possible.....

you commented in an earlier post that you were having problems with your filler cap sticking. Assuming you have fixed that problem and the car was running well then, it may now be the case that without the vacuum in the petrol tank to restrict fuel flow, it is now running rich (as mentioned above) due to the less restrictive flow. It may be a little far fetched but i though it was worth mentioning. Idea

Dave
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bw · Posted: Tue Aug 19, 2003 12:37 pm Post subject:

Thanks Dave, I haven't fixed the filler cap problem because I can't replicate it. Every time I put fuel in the cap comes off easily, but Tracee still has trouble Confused

Anyway, it may have been smoking before, it's just I hadn't followed the car down the road before, so who knows?!

Another possibility - could it be something to do with the (oil) breather getting clogged? Someone suggested this, but I don't understand how that's linked?