blown piston ring?

hey guys when i start my car up it shoots white smoke out of the exhaust/tailpipe but then it goes away (only happens every now it then) stopped for a while and started again randomly. Was driving today and then a heap of smoke came out , pulled over turned car off for a minute of two checked bay everything seemed fine. started car again blew smoke then stopped (blew again while i drove down the road then stopped) pretty sure its stopped now. any ideas? i was thinking blown piston ring..

any help appreciated

thankss

im no mechanic, but from my understanding white smoke = head gasket problems

If its more bluish smoke, than its a seal or piston ring problem, as its the color of oil burning...

Check your coolant level everyday, if it goes low, so possible Water is leaking in the chamber which possibly is head gasket.
Do compression test, than do Leakdown test.

Ah ok thanks guys what's worse but blown head gasket or piston rings ? Um pretty sure my coolant has been on the same level for quite some time so don't think that's the problem . But yeah will get leakdown test and compression test done :) thanks fellas

white smoke is usually burning coolant/water

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Originally Posted by x3cindymichael

Ah ok thanks guys what's worse but blown head gasket or piston rings ? Um pretty sure my coolant has been on the same level for quite some time so don't think that's the problem . But yeah will get leakdown test and compression test done :) thanks fellas

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Piston ring is worse

either can be bad depending on wear & tear of the engine.

Sorry to hijack the thread what does leak down test do and is one of these hard to perform?

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Originally Posted by blabla

Sorry to hijack the thread what does leak down test do and is one of these hard to perform?

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leak down test mean, is when they test each cylinder and know where is it leaking(example:intake,exhaust,head,block, pistons...)
compression test is when it show the compression on each cylinder, which can tell if its holding compression or not. Some times compression could be good but but not 100% accurate

Check ur oil off ur dipstick, if it's milky then it should b ur head gasket

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Originally Posted by hmetro24

leak down test mean, is when they test each cylinder and know where is it leaking(example:intake,exhaust,head,block, pistons...)
compression test is when it show the compression on each cylinder, which can tell if its holding compression or not. Some times compression could be good but but not 100% accurate

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Thanks.

ah okay thanks guys. yeah i checked dipstick oil is normal color . my mate had a blown gasket and his oil was cofee/milky. but yeah will be getting a compression test done soon (anyone know how much one of these cost? ) put some fluids in from supercheap over the weekend (something about fixing compression of cylinders and stop smoke.. just to help it a bit for now) thanks for all the input guys

comp test takes a few 5 minutes so it shouldn't be costly. You remove the spark plug and unplug the injectors then screw in a compression gauge and crank the engine to see how much air pressure it can withstand. Then tell us how much each cylinder held here and someone will be able to tell you if you're ok or not.

jump to supercheapauto get compression test tools( got mine for 30$), 16mm deep socket + extension + ratchet.
take spark leads, Note: Do not take the spark lead from the distributor, you may forget how to put the back
take spark plugs out. easy way to take the spark out: Unscrew the spark plugs until it come loose, put the spark lead on the spark hole until it clip to the spark plug and take it out.
screw the compression tools in.
crank the engine for couple of seconds, write down the psi,
repeat the test for each cylinder.

you can try wet compression after you do dry compression. put a lil bit of oil inside the cylinder throw the plug hole and repeat the test again and write down the psi for each cylinder.
Wet test will tell that pistons rings are bad or good depends on the psi you are getting.
when ever you finish the test put everything back, start the car. it will blow smoke, do not panic it the oil you put on the cylinders it will take some time to burn all the oil.

for example:
dry test. cyl1 : 180 psi cyl2 : 180 psi cyl3 : 180 psi cyl4 : 180 psi +- 5-10
this mean the head is allright
wet test cyl1 : 240 psi cyl2 : 240 psi cyl3 : 180 psi cyl4 : 180 psi +- 5-10

this will mean that compression is good but piston rings in cylinder 1 and 2 are bad because the pressure jumped up.
dry test: cyl1 180 psi cyl2 : 130 psi cyl3 : 125 psi cyl4 : 180 psi +- 5-10
if you get like that, this mean some thing is wrong in cly 2 and 3, could be valves seat, bent valves, wrapped head, headgasket.

how to do compression test
how to do leak down test

Pull the fuse for the ignition circuit before you run the compression test. If you have the system trying to generate a spark without the sparkplugs in, you can damage your ignition coil.

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Originally Posted by aaronng

Pull the fuse for the ignition circuit before you run the compression test. If you have the system trying to generate a spark without the sparkplugs in, you can damage your ignition coil.

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not many people think of this,.

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Originally Posted by aaronng

Pull the fuse for the ignition circuit before you run the compression test. If you have the system trying to generate a spark without the sparkplugs in, you can damage your ignition coil.

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ohshit good idea lol