Engine / exhaust help

If the steam goes away when the car is hot, you may have some moisture left in the exhaust, it may take quite a few miles to clear it.

If the steam is still present when the exhausts are hot, you probably have a few cracks in the head.

 

It may be hard to distinguish from steam, but if the steam/smoke is blue-ish, this may be caused by oil creeping into the combustion chamber and cylinders. My car used to emit thick clouds of almost-white steam, and more than one mechanic mistook them for condensation while in fact this was oil being burned by the engine. The typical pattern was: a large could upon start-up, burning all that oil accumulated in the cylinders while the car was parked, which would disappear after a few minutes of warm-up (similar to condensation), and then small puffs whenever I would stop at a traffic light or anytime I would get back to idle for a few seconds and oil would have time to creep again into the combustion chambers.

Key symptoms of this were: oily spark plugs and higher than usual oil consumption. Another sign this wasn't condensation was the fact that smoke would come back or thicken at traffic lights, when idling with the engine at operating temperature.

This was caused by using a 10w-40 in an engine requiring 10w-50. An oil change with the correct grade cured this issue for me.

Other possible causes of this particular issue include worn valve stem seals, poor valve sealing and/or worn piston rings.

 

Oil : as explained by Peter, when you depress the accelerator oil can find its way through the valve stem seals (and even more if you do not use the proper oil), this could be consistent with "intermittent puffing".

Coolant : if you have a few cracks in the head: some exhaust gases can find their way in the coolant circuit, which raises coolant the pressure. When you go back to idle, the accumulated pressure pushes the coolant into the exhaust pipe through the cracks. Same annoyance as above (bad looking exhaust when slowing down).



The rattle could be due to a bent valve or valve not properly shimmed? Is the car maintenance up to date including valve shims, valve & valve guides? The owner manual recommends to check the shims every 30.000km, the workshop manual recommends to replace the valves and guides after 50.000km (see section B31). The 50.000km of the workshop manual are probably excessive, but the original valve, guides and stems are not going to last 100.000km for sure.

Mixing incompatible oils does also generate some rattle when cold. If I were in your shoes I would flush oil twice (as per the owner manual), and from then on check whether the car burns coolant or oil.

 

When is the last time you checked the tension in the timing chain? I’d start with that. The rattling sound could be slack in the chain. Also if you have twin distributors then a lot of slack will cause ignition timing issues which can lead to differences between the left and right banks.

 

1) Does it stop smoking when warmed up?

2) Does the smoke dissipate quickly in the air or hang around?

 

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