Often, now I am driving up a mountain, and no problem. But when I go down a mountain, I am almost never accelerating, even if it means my speed actually isn't all that fast.
This isn't happening when I am going up, only down...so when I have hit the point where I do need to accelerate, and what I feel is the weight of the car has really pressed down, my exhaust will blow out a grey or dark colored smoke. Especially when there is a turn occurring just before I have to accelerate. The smoke looks to me, like oil related, but I cannot see from where. I just had my seals replaced, and don't see any apparent leaks. Although I seem to be eating oil, and the exhaust is old, but doesn't need replacing yet.
Is it possible there is some leak and it gets burned off on the exhaust? I can't imagine blowing a huge puff of smoke on to the driver behind me as something to shrug off. This didn't happen before I took the car in to have the seals replaced, by the garage that power washed the engine.
I know one time, back in the day, I did I terrible job of adding oil to my car, would drive it, and occasionally for a couple weeks later it would just blast a ton of white smoke off the back because the oil was all over the engine and slowly ran down the bottom and onto the exhaust...

So any ideas what is going on? Should I be concerned? Etc etc etc...please...and thanks

White smoke ? Have you checked for signs of water in your oil ? You may have a failed gasket or cracked block or cylinder head.

What seals were replaced? There are 3 colors of smoke you can make- black, grey-blue, or white. Sometimes it's hard to discern which is which, especially if you're driving. Black is running too rich, grey-blue is burning oil, and white is coolant in the combustion chamber.

As it seems to happen when you're off the accelerator or been off it for a while, that means there's high vacuum in the motor and you may be sucking oil past the valve stem seals and that's getting burnt off when you accelerate.

But it could be lots of things. Gas? Diesel? What kind of car? How old? What does the oil look like on the dipstick?

just bring it back, surely you got warranty on the work no?

Also could be that they spilled some oil on the pipes when doing the work....but that should have been burned off by now.

(I assume it is a gasser and not a diesel right, you should see the cloud my diesel makes hahaha)

You need a new sturdier vehicle....a Jeep maybe

Unleaded 95/Bezine/Essense/Gas....Mazda 323 F 1996, It's been a while since my last oil change, I have been basically adding oil to it for a few months now. Before it was leaking oil, and that was the reason. Now I don't think so.
The oil looks dirty. The dipstick, it's funny you should ask that...as it's the first time I have been confused by one. I can dip it in there a dozen times and it almost never gives me the same result. It definitely is always on the minimum marker thick, but will give a variety on thin strains or thick marks on up to the full line.
I was testing some accelerating today. If I roar the engine after pulling out of the parking lot, no smoke. If I am coasting for 2 to 3 kilometers from 40 to 80/85kms and then the car starts to gradually coast up the next hill and I give it just a tap on the gas, big smoke plume for the guy behind me. I think it's the in between color, no egg shell white, not a Gargamel black cloud. And if I floor it on the highway, no smoke ever( I think). I put a card board box underneath the engine last night, and this morning there were no signs of oils leaks underneath. Could this be an old exhaust problem?

It's an idea that has been on my back like a monkey.

About 99.9% sure it's valve stem seals. If this was a Merc or other exceptionally solid car, I'd say have it fixed. The thing with valve seals, is if you're going to do them, then you might as well do a full valve job. At Swiss prices that would probably cost more than the value of the car. And then you're putting a nice rebuilt head on top of a questionable lower end...

How much longer do you have on the MFK? I say just drive it till you have to renew, then say goodbye and move on.

What price you figure that job to be say some where like France?
Otherwise I have to check. How many years between MFK's? This one was last done about October last year.

MFK every two years for a car that age. I have no idea what head work would cost in France, but I would bet you a beer that you aren't going to have it done here for less than 2K, which is about the average price for that car.

If you have new valve seals (assuming a vehicle WITH valve seals, not all have them), then valve guides or rings would be my bet.

Tom

You might want to take it to a German garage for a quotation. As Monday 1 st August isn't a holiday in Germany, why not pop over for a quotation?

This is an independent garage I have used twice, I find his prices good, and he was very professional, http://www.karosserie-braendlin.de/index.php best to ask for an appointment, info@karosserie-braendlin.de

He is near the train station for the train to Basel http://maps.google.de/maps?hl=en&tab=ll

So how long can I drive the car like this? And will it be a problem to take it long distance?

Does he speak english? I am working 12 to 14 hours a day for the next 10 days, but might find some time in a couple weeks.

No, it will just be a problem to pass the emissions test.

Tom

@ Confloosed: sorry, I don't know if he speaks English or French.

It might be better to simply see what happens at the next Abgas test. If the engine only emits smoke from the exhaust under de-acceleration, then it may pass an Abgas test.

For a 16 year old car, I would fully expect it to burn a little oil. The costs involved to fix it would not make any sense. As some others have suggested on here, just keep running it and hope it passes the Abgas. If not, then it may be time to look for a new car It's not worth spending the money on a relatively old car.

Mechanically, a litlle smoke out of the exhaust does not mean the engine is finished. I have had plenty of engines which burn a little oil but continue to work well for years to come. Just keep an eye on the amount of oil being used. (Keep in mind some car manufacturers state that up to 1litre per 4000Kms is normal. Even some cars are using 1 litre every 1000Kms but this is unusual)

Not really. The engine is still working ie: Air is sucked in to the cylinder, the inlet valve closes, the piston compresses the air in the cylinder and the exhaust valve then opens and releases it. This means there is relatively no change to the way the valve stem seals are working.

In most cases, worn valve stem seals are noticeable during cold starting after the engine has been stopped for a while. The oil seeps down the valve stem overnight or during long periods of rest and sits on top of the valves or drops down onto the piston. During starting, blue smoke can be momentarily seen coming out of the exhaust but clears up quickly. (Modern cars do not really suffer from this any more)

What is changing during deceleration is the Pmax of each cylinder. This is the maximum firing pressure. During deceleration, little or no fuel is admitted into the cylinder so the firing pressure is reduced down to the maximum pressure reached by simply compressing the admitted air.

The effect to the engine is that the piston rings are not as mechanically loaded as they would be under normal firing conditions. (During firing of a cylinder, the piston rings actually push outwards and seal against the cylinder liner wall) On a worn engine, it can be that the piston rings are not as effective at maintaining the seal between the lower and upper side of the piston rings which may allow oil to pass as well as compressed air into the crankcase. The effect of this will increase the oil sump pressure which in turn can cause a positive pressure in the sump and up to the camshaft cover. The result of that can then push oil past the piston rings and the valve stem seals.

As always, it is a good idea to check that the crank case breather is clear as this prevents this build up of positive pressure.

That was the Spec from the factory for a Porsche 911 in the 1980's, however mine uses was less than that.

Ahh, the good old days when checking and topping up the oil was a weekly task! A long time ago, I used to have a Peugeot 406 1.9 Petrol. It used so much oil that after a while, I never changed it! (Around 1 litre every 700 to 800miles) I worked off the theory that it had a constant supply of fresh oil added regularly so only the filter needed changing. (And that the car was old and worth nothing)