MisterRisky

valve adjustment should not cause smoking... but worn guilds could cause ticking... keep in mind that seeing smoke can also make you hear ticking better.

gchristofi

Decided to go a bit further and be brave enough to take my own spanners to the car for the 1st time. This was a whole new way to enjoy the car!!!

I was trying to see if there was any evidence of an overfill that could explain the smoking at idle.

Got as far as removing the MAF in my search for puddles of oil... did I go far enough and low enough in the intake system.

Photos attached show the removed MAF (which appeared fairly clean and certainly moved smoothly) and some gunk inside a removed hose connection? Also a closeup shot where the MAF connects to intake that shows evidence of seepage of some sort (looks like a shadow)

Any comments on these pics?

Cheers
Greg

jim_l

you know i have been having the same problem, smoke on idle after i had the valves adjusted and a oil change with overfill now i cant seem to get rid of the smoke i also drained off enough oil to bring it well below the top mark on the oil stick. how long to clear the smoke ?

gchristofi

Ok, sorry to keep resurrecting this old thread but I am now more confused than ever. I just visited my specialist and sure enough, on arrival the car is smoking like a hot dog stand and the problem doesn't even clear up with higher revs.

So, made plans to get the top end rebuild done and left sure It was the correct way to go.

By the time I got home, no more smoke!!!! For love nor money I can't get it to smoke anymore!!! The last 10 test drives have all resulted in smoke so I'm really confused.... Really can't explain this intermittent behaviour.....

Any ideas? perhaps best to get compression test before agreeing rebuild? Could it be a ring that is just cracked and moving around and therefore sometimes smokey, sometimes not? HELP.

darth

This is what I'd do:
Drive it since it is showing signs of no smoke. If it stops permanently great, if it starts smoking again to the point you're getting annoyed pull a sparkplug out of each cylinder (i.e. you could probably do this yourself) and look at the plug for wet oil deposits on the plugs - this will tell you which cylinder(s) to concentrate on. Then if you have a compressor or a good source for compressed air, (i.e. 100psi @ 5cfms) apply it to each cylinder and listen as to where the air is escaping (i.e. exhaust - exhaust valve, intake - intake valve, crankcase - piston rings). If you want to get more precise and spend some money, have a leakdown/compression test done which should tell you if the piston rings are pooched. If the leakdown points to leaky valves, that does not cause smoke - worn valve guides and seals allow oil to enter the combustion chamber and in turn smoke. There is a method to inspect/change the valve seals without dismantling the top end by injecting compressed air into the cylinder via. sparkplug hole in order to keep the valve from dropping into the cylinder while the valve spring is removed, although if the piston is at TDC it won't drop very far anyways.

Hope this helps
Bill

gchristofi

Hi Bill

much appreciated. I was thinking along the same lines that I should at least have a compression test done before agreeing to top end rebuild... Pretty sure that all problems external to engine have been eliminatated... i.e. overfill.

There is just one more thing that is strange. Recently, my oil pressure when cold and idling has been far higher than I'm used to seeing.... these are the oil pressure readings I get....


Cold Warm (gauge at 8 o'clock)
Idling approx 800 3 bar 1.5 bar
1500 4.5 bar 3 bar
2000 max(just under5) 4 bar
2500 max max

I'm pretty certain that prior to removing one of the breather pipes across the top of the engine, my cold idle was only ever showing just above 1bar. Are my pressure readings high now? What could be causing this sudden increase in oil pressure? Is it bad? (oil is 10/40 semi synth engine 67k miles from new).

Cheers
Greg

TheOtherEric

Is your brake fluid level dropping? Read on...

I just started burning a LOT of white (not blue or black) smoke when idling, mainly during times of braking, like stopping at lights or in traffic. Turns out my master cylinder seal just went bad, so braking squeezes out fluid that gets sucked thru the vacuum booster then all the way back into the engine intake. I saw my brake fluid level drop significantly, but the brakes still work fine. I just ordered a new M/C.

Sounds like it may fit your symptoms, too.

gchristofi

TheOtherEric
That is really interesting and would never have thought to check that...... although, without looking at my car the smoke has been bluey black with carbon depostis on my bumper BUT still worth checking ....
Cheers
Greg

darth

After hearing you're seeing a change with oil pressure I take back the comment of "Drive it since it is showing signs of no smoke". Oil pressure in these engines is critical and a sudden increase in oil pressure for no apparent reason could be a sign of a restricted oil passage. Much like when human arteries get clogged - blood pressure increases only in an engine an oil restriction could cause oil starvation to a bearing.
Simplest thing to do at this point if you want to do some DIY is pull a sparkplug from each cylinder and look at them visually for wet oily deposits on the tip - this will atleast tell you what cylinder(s) are suspect. Definitely get the problem diagnosed with a compression/leakdown/visual check of the valve seals before you start tearing down the top end.

Bill

gchristofi

Yes, will do . cheers for all advice. Will report back findings.

Are those pressure readings high by average standards then?

darth

Not sure how to interpret your readings - should we assume that the 2 values for each rpm are now and before (i.e. hi and lo) in which case relative to mine they are hi but more importantly is the fact that they changed so much relative to themself - all guages are not the same.

Bill

CraigyB

I would expect oil pressure to be higher when colder as the oil is more viscous.

gchristofi

Ah, I see. I actually wrote that as a table with columns but the auto formatting has taken out what it interpreted as fatuous spaces.... The Bar readings are all for my engine as it is now. The first reading for each rpm level represents a cold engine and the 2nd reading a warm engine (with guage at 8 0.clock). I never really noted what the old reading were prior to removing the breather but I know it did not show 3bar on cold idle!

RS_Sam

I have recently bought a '90 c4 with 50000mi on the clock and have also noticed smoke at idle but only once the car is on temperature. Have you solved your problem yet?

jim_l

mine was overfill, cleaned the intakes and isv and its fine but you need to check the oil level using the dipstick with the oil temp gauge between 8 and 9. i was having a hard time reading the dipstick my local shop give me a tip of pressing your thumb on the dipstick to find the oil level, will leave prints in the oil not on the dry stick i have also had minor oil leaks from the oil bridge oring and a hose to the power steering pump cause smoke on idle with a hot engine.