I write this post because for a few weeks I've been looking for a new diesel car to replace my wifes smashed up Picanto. I don't have any brand loyaly and have been looking at various makes and models to take advantage of the lower tax bands.

 

After looking at multiple cars I keep getting the same thing which worries me. Smoke from oil filler cap and/or oil dipstick! Some smoke and some don't but it does seem to smoke more on a VW and Skoda. I've found a nice little Skoda 1.6TDI 90, 2011 car with 52000 miles and full service history that I want to buy and hence my post.

 

I don't buy many cars and have them for a long time due in part to buying the right car in the first place. When I go and look at a car I make sure it's started from cold, and see if there is anything ominous comming from the exhaust first. I very breifly remove the oil filler cap slowly to see if there is any smoke coming out from there and to check for white residue under the cap, and then the same with the oil dipstick. After that I take the car out for a good drive on the nearby roads and then check to see if there's smoke comming out the exhaust, and then the same with the oil filler and oil dipstick again. After this trip there was already a little wisp of smoke coming out from under the cap but after I removed it there was a lot of dirt sitting between the seal or the cap and the rocker cover (not doubt caused by dirt collecting around the oil fill recess) that had prevented a proper seal.

 

Can I ask forum members that have experience of this engine to confirm if it's normal to get oil smoke coming out of the oil fill hole on this model of Skoda please.

 

Thank you for looking,

 

Andy

Edited 29 September, 201510 yr by Hightower79

I can't comment on that particular engine but I have a 1.4 pd tdi and after a tun, when checking the oil level when the engine is warm, there is never smoke from the dipstick.

There is however a very small amount of smoke from the oil filler cap. However this only seems to occur when the engine is hot (perhaps too hot to be checking the oil) the manual states to check when 'warm'

Had a new 1.6 CR90 TDI in 2011, excellent engine, but a little let down by possible ahead problems with EGR valves, and other

Peripheral items. (I got rid of mine after 18 months because of recurring electrical problems)

 

I can advise that if you remove the filler cap of course you will witness a smoke/vapour element. When you remove the cap you are allowing the crankcase pressure to relieve itself through that exit. When the cap is replaced, the crankcase pressure is then recirculated through its designated path.

 

You mentioned the presense of a milky residue inside the cover - if this is the case - this indicates that the vehicle has been driven too slowly (or too few revs) and has never really reached full operating temperature. OR the wrong oil has been used. Normally it is running at too relaxed a pace, and never really reaching full running temperature that causes this muck.

The CR90 engine is not like a traditional old diesel - it needs to be driven in a spritely manner to get the best from it. Dawdling about at low revs is NOT the way to treat this engine. A good prolonged thrash on the motorway quite frequently is to be recommended.

 

In regard to smoke from the exhaust, yes of course some is to be expected - however the CR90 is normally very good in this respect. People coast down long hills, or leave the engine running at idle for a long time, so expect a brief puff of smoke when unit is rev'd up in these circumstances. Filtration is usually the key to complete combustion performance.

Thanks for the replys. There wasn't any milky residue on the cap just the smoke/oil vapour coming from the oil fill hole. My experience of diesels are older bigger lower reving engines like the 3.1TD one in my Trooper 4x4 which doesn't smoke at all when the oil fill cap is removed.

 

Thanks 2ndSkoda for your thorough explanation however I would still welcome any other opinions/experiences from other members.

Hightower, yes you will often get some vapour from the oil which is mostly steam from the oil filler orifice if you remove the cap after start up and again later when the engine is warm/hot. It's normal. Removal of the oil filler cap interferes with the crankcase gas recirculation, as said by 2ndskoda causing the gases to emit to atmosphere. Same with the oil dipstick. The other thing that determines how much vapour comes out of the oil filler orifice is how much water there is in the oil. This is usually condensation that has formed in the oil and also comes from combustion bypass gases directly into the oil after start up. The gases bypass the piston rings especially when the engine is cold carrying water with them from the combustion process. Don't forget for every gallon of fuel you burn you produce one gallon of water, some of which goes straight into the oil. If the water hasn't evaporated from the oil during a run then it will exit as steam in a very visible way once the oil cap is removed. It's like this for all modern engines. What you do not want to see is actual blue smoke coming from the oil filler cap area especially when the engine is hot. That indicates worn piston rings and bores. 

I'd like to thank everyone for their help and advice.

 

I did some homework and it seems a little oil vapour/smoke is normal for this type of engine. I ended up buying the car I was looking at and have been driving it around for a week now. I must say that I am loving the driving experience and am thus far pleased with my new purchase.

 

Andy