Hi everyone, this is my first post, hope you can help. I have a 1999 1.6 GLXi which runs superb and goes like the clappers which is why i am confused by recent happenings. When i am going downhill and the engine is just on over-run everything feels just as it should untill i get to the bottom of the hill and need to put the gas back on, then i notice a large puff of grey exhaust smoke which lasts for about one or two seconds and then stops. The engine performance is not affected and it only happens when the gas is applied after the engine has been on over-run. Any ideas please.

piston rings worn?

Welcome

Sounds more like the valve stem seals are letting oil pass.

Hiya Carneal.

One of this pair are almost certainly right, but I'd not like to say which. Are there any other signs we might use:-

Lack of power.

Puffing smoke on start up.

Faint blue smoke when accelerating?

Failing this, a compression test should sort out which is which.

I'd have thought valve stem seals or worn rings leading to oil in the combustion chamber would have lead to blue smoke coming out of the exhaust.

If the smoke is grey it sounds more like excess fuel being burnt off as the throttle is opened increasing the amount of air into the engine. If the engine is braking the vehicle with the throttle closed down a hill then there is a huge depression in the cylinders so its also possible the exhaust gases are not being expelled out the engine as normal until the engine is back driving the vehicle.

I see where you're coming from, but IME it depends on quantities whether oil smoke is blue or grey. More oil tends to make the smoke greyer.

I see where you're coming from, but IME it depends on quantities whether oil smoke is blue or grey. More oil tends to make the smoke greyer.

I've been behind a vehicle that went down a long steep hill with the throttle closed. At the bottom when the driver started to drive normally and opened the throttle the amount of blue smoke that came out for about 30 seconds as they drove up the road was so bad it was almost like the engine had blown.

Edit :- Where's Lummox or VRStu when you need them?

Thanks to all of you for your ideas, much appreciated. I have just taken it out again to re-check the colour of the smoke and to confuse matters i can best describe it as bluey grey. The longer the hill the more smoke at the bottom when i throttle up but it only lasts for a couple of seconds and it in no way is affecting the performance. It really does drive well. If it helps there is a build up of black sooty carbon in the tailpipe.

Had the same problem with my old rover 214 it went like stink but had exactly the same problem.

No-one seems to have asked you but are you having to top up oil?

If not it isn't burning it

That sounds very much like early stage oil seals. What happens is that some oil gets sucked past them when you reapply the throttle following the period on over-run.

Harry, I didn't ask about oil consumption because the oil consumption at this stage isn't measurable with a dipstick IME.

Thanks once again. Yes i am having to top up oil but only about a pint every two or three weeks. Is this exsessive?

No idea. Consumption against mileage would be more helpful. Given that you're getting visible oil smoke though sometimes, I'd say that the oil consumption could be lower.

Pinkskud has a 1.6 with a few miles on it. It may be worth finding out how much oil another car uses as a comparison.

I have a 1.3 so i cannot help i'm afraid

Thanks. I would say that i do about 5 to six hudred miles to a pint of oil

That's bad, at least for most engines.