revving and smoke

[migoreng]

hey when you stand outside your car and rev it hard does that tell you a lot about the engine?

i notice mechanics use this method...my car doesn't make much smoke at all when revving hard...it just squirts out some thin black and light blue smoke which looks pretty normal to me...

is reving the car hard and taking off/driving the same thing? i would think with load on the engine there would be more pressure buildup and stuff in the engine and if an engine would smoke then it would smoke while driving right?

so if you want to check for any smoke then isn't it best for a mechanic to follow behind and observe for smoke rather than just reving the car when stationary?

what do you think?
this weekend i really need to find a mechanic that knows how to diagnose my car properly...
:(

[mocchi]

i dont think revving an engine tells a lot about the condition of an engine. leak down test would be a better way to look for information.

you're saying when the mechanic presses the throttle valve thing from engine bay, and you're comparing it to when you're inside the car pressing gas pedal with your feet?

i dont know about the difference exactly but i think they do the same thing.. stationary or on the road (with load or without load on drivetrain)

oh whats wrong with ur car anyway

[Jnr_Mint]

Rev the car - get someone to be at the rear of the car lookin at the exhaust

White smoke is due to water getting in to a cylinder from a bad gasket, cracked block or a cracked head.
Black smoke: to much gas/fuel being burned in the engine
Blue smoke can be transmission fluid or If it's constant when the engine is on, then the rings etc are worn and need to be replaced


You can make an assessment on compression by opening the oil cap whislt the car is on and place ur palm over the hole, u should feel a strong vacuum, if u dont, it means the engine has lost compression via the piston rings.

Hope this helps

[AE092]

black smoke: air/fuel mixture too rich.

blue smoke is: air/fuel ratio too lean.

Revving an engine cleans out the carbon deposit build up in the engine, exhaust and intake. Good for the car (within reason) and bad for the enviroment. Using 98 Octane fuel will also "clean" the engine to a degree

[trism]

ahh


blue smoke means the car is burning oil

not teh mixture is too lean

[hooyn]

white smoke in the morning is just condennnnsaaatttioooonnnn

[aaronng]

Blue smoke does NOT mean transmission fluid being burnt.

[migoreng]

=_=
i know what smoke colours mean...
main Q is should you have someone observe your smoke by following your car or is the revving method good enough???

[Zilli]

Blue smoke does NOT mean transmission fluid being burnt.

jesus christ... you beat me to it Aaronng

[Nax]

grey smoke with a tinge of orange/red means your car is on fire

if the car is smoking constantly while ur driving its an issue, it tells u different things at different times i suppose

[VTECMACHINE]

black smoke: air/fuel mixture too rich.

blue smoke is: air/fuel ratio too lean.

Revving an engine cleans out the carbon deposit build up in the engine, exhaust and intake. Good for the car (within reason) and bad for the enviroment. Using 98 Octane fuel will also "clean" the engine to a degree

Point 1, correct.
Point 2, LOL... incorrect it's engine oil burning, not transmission fluid.
Point 3, Revving is bad for the environment? So is driving a car normally. haha. 98 RON octane burns cleaner also.