Engine Condition

CITMAN · Post by **CITMAN** » 17 Jul 2003, 19:54

Ive got a Citroen Zx 1.4i with 78000 miles. Im little concerned about the condition of my engine because one of mates said that when he was following me the car was smoking a little. I have changed the oil and filter every 3000 miles with semi synthetic oil for all its life. So what checks can I do to determine the condition of the motor. Its does use a little oil but not excessive. I put the consumption down to couple of oil leaks on the engine but doesnt drip on the drive so I dont worry about them.
Thinking about it during the period I did put a fair bit of redex in the petrol tank during the period in question. Would the redex cause a bit of smoking during driving.

jeremy · Post by **jeremy** » 17 Jul 2003, 20:23

Yes Redex can burn smokily if enough is used.
How much oil is a little?
Oil leaks can themselves be an indication of a knackered engine. If the bores/rings are worn the crankcase will pressurise and fumes will come out through all the seals and joints bringing oil with it. just because an engine is pressurising doesn't mean it will burn oil.
What colour are the fumes from the exhaust, when do they happen? Its also worth a quick look at the simple servicing items like air cleaner, breather pies etc.
Jeremy

CITMAN · Post by **CITMAN** » 17 Jul 2003, 21:16

I havent really measured the oil consumption yet properly. I dont usually let the oil level drop to much below the max mark on the dipstick and recently topped it up slightly as the levels was about 0.5 cm below the max mark on the dipstick thats was after about 600 - 700 miles after the oil change and did overfill it slightly so this figure might not be accurate.
Changed the air filter not long ago and noticed a little bit of oil in the breather system but non on the old air filter or the filter housing.
When I open the oil filler cap with engine running there are some fumes which escape for a few seconds, and then if I place may hand over the hole I can feel a slight patter patter on my palm. On pulling the dipstick out there are slight fumes which escape but if do this on my dads renault laguna the fumes which escape are a lot greater.
The only time I have noticed a powerlosss is when driving the car off on a very cold winters morning, which soon warms to the task.
The engine sounds very smooth even turbine like inside the car with no heavy knocks or rumblings just some valve gear tappty tap when the engine is cold which disappears when the engine warms up to operating temp.

jeremy · Post by **jeremy** » 17 Jul 2003, 21:34

By serious oil consumption I'm talking about 250 miles per litre - yours would seem nothing to be worried about.
It would seem that its not oil causing the smoke - so it sounds like a mixture problem. How observant is your friend? - could he have seen an accumulation of water vapour which had collected in a silencer or similar?
If he's reliable and you are smoking then it must be related to the engine management system. Have you got a catalyst? It seems that often the cold start sensor fails, causing the engine to run rich. If you have a lambda sensor it senses too rich a mixture and weakens it off when the engine is running. This has been gone into recently in great detail by people much more knowledgeable than me and I would recommend a search.
Jeremy

CITMAN · Post by **CITMAN** » 17 Jul 2003, 21:39

The car recently went in for its mot and passed the emissions the flying colours CO 0.16% HC 71ppm at fast idle and natural idle test was CO 0.2%. of lambda was 1.02 which is within spec I think

jeremy · Post by **jeremy** » 17 Jul 2003, 22:00

sounds OK - I suggest you get it well warmed up after a fastish run to clear the exhaust and then get someone else to drive it while you follow and see what happens - It may have inhaled a few drops of oil before your friend looked at it and a few drops will produce a load of smoke.
Jeremy

CITMAN · Post by **CITMAN** » 17 Jul 2003, 22:03

thanks a lot I appreciate your advice Jeremy
regards
Citman

sooty · Post by **sooty** » 18 Jul 2003, 00:43

One thing to be sure of if you have oil leaks on an engine of a reasonable amount mileage, is to be sure that the crankcase ventilation system is not block or restricted. So not to cause any pressure build in the engine blowing the seals and gaskets, unless your engine is really w**ked.
Sooty

Richard Gallagher · Post by **Richard Gallagher** » 18 Jul 2003, 01:25

I'm not sure if the 1.4 has them, but it could well be something simple such as valve stem oil seals. These are the little rubber seals which hide behind the valve springs. With age and heat the rubber goes hard and brittle, thereby letting oil pass down the valve stem and into the cylinder.
If they are to blame you will generally see blue smoke on start up first thing in the morning as the oil has dripped into the cylinder overnight, in certain cases the smoke will still be visible some time later.
If the engine has suffered bore wear smoke will be visible after staying off the drive for some time such as when decending a long hill, then when drive is applied the excess oil is burnt off and produces blue smoke.
Generally if the engine is burning oil the smoke will be blue, excessive mixture black.

DLM · Post by **DLM** » 18 Jul 2003, 03:06

I always thought the "hill test" was an indication of valve stem oil seal problems Richard - my BX16 estate produced plenty of blue smoke in those circumstances, but new valve stem seals stopped the oil burning completely.
David