[junek]

I just chucked a new set of pistons and rings in my sierra engine.
Now I have it going again, it is blowing some white smoke - it never blew smoke before the rebuild.
Smoke blows when you accelerate after idle for a while. For example if you cruise into a set of lights, wait for a little bit then accelerate away. Does not blow at idle or under normal driving or if you accelerate from one speed to another - even if you floor it.
Does blow a little on start up.

Any ideas?

Valve stems seals? - strange they would show up now and not beofre the rebuild.

ps. I have just got it back together and have cheap 20w40 oil it it. I will change to better 15w40 after the first 100kms or so to give the engine a bit of a flush out after the rebuild.


thanks

[ball]

Did you hone the block?

Why would you need to flush out an engine after a rebuild. When it is apart is the time to clean any filth out.

If you did a half ass job, you will end up with poor results

[royce]

did you bore and hone the block?

could be the cheap oil is getting past teh valve stem seals and burns easier than the good oil, ou really need to run the cheap oil for 1000km to let teh rings bed in

[want33s]

Could be rings fitted upside down.

[zuk85]

could be valve stem seals, Or a malfunctioning PCV valve. The ball-check might not be fully seating, allowing small amounts of oil to sneak past and into the combustion chamber. A cheap and easy fix.

or could be head gasket?

best way to tell quickly get behind your car and smell when the white smoke is comming out. does it smell like oil or does it have a sweeter smell to it which can be caused from anitfrieeze.

or it could be

white smoke from the exhaust that will disappear after the vehicles engine has warmed up to it's normal operating temp. This is a normal reaction called condensation... condensation is the result of a small amount of water/dew being drawn into the exhaust when cooling, usually collecting in the muffler and/or the catalytic converter and is caused by our friend mother nature..... like when you see your breath on a cold day...

[zooky08]

white smoke usually indicates coolant in the combustion chamber. did you reuse the head gasket or buy a new one?. did you tension up the head to the right specification?.

[junek]

thanks for the replies guys.

Situation has changed: I just took it for a drive and now it is constantly blowing smoke. Particularly bad after accelerating away from sitting at lights or intersection. But definately blows a constant white smoke. (WITH OIL SMELL)

No coolant in the radiator - just water. I was just going to check it was all running ok before flushing radiator and adding coolant.

I did not hone or bore the cylinders. I used standard sized rings and pistons.

I used new gaskets all round.

"rings could be upside down" = oh shit. Call me an amature (because I am) but i did not know they had to be a certain way up!!! shit shit shit.
Do all rings have a certain way up and if so how do you know which way should be up.????

Is there an easyer way to change rings without head off and sump off and lift them out the top of the block?

[Fatzook]

If you didn't bore or atleast hone the cylinders, its probably the cause.

Just like you machine your brake rotors when you fit new pads, or machine a flywheel when you fit a new clutch, you must ensure that the cylinder bores are rounds and smooth before fitting correctly sized pistons and rings.

[zooky08]

also if you have no crosshatching in the bores there wont be proper lubrication and sealing

[junek]

The cylinders were in very good condition so i thought it did not need honing. The pistons and rings were a nice tight fit. Wouldn't a set of rings bed in to a cylinder even if not honed? like brake pads bedding into a disk? Tell me if i am wrong...

[junek]

zooky08 wrote:

also if you have no crosshatching in the bores there wont be proper lubrication and sealing

oh, ok. I should have asked a lot more questions before I did this.

There were some cross hatches, but I guess not nearly as much as there would have been if I had it honed.

Jamie

[JrZook]

Well looks like your gonna have to pull it down again and reassemble it properly. Ring to bore interface is alot different to bedding in pads to rotors. Rings need to wear into the bore to get a good seal, hence the reason for honing. This roughens up the bore so when new rings are installed they bed in as a matched pair for a good seal.

[junek]

right, well, um. shit. I take it honing involves sending the block to a engine shop?

Thanks again for the help.

[tanshi]

I would send it away to make sure its done right and save you money in the long run.

[junek]

yep. good idea.

Thanks guys for your help

jamie

[Fatzook]

I have a bead hone for sierra cyl size, but its messy (drops crap into sump when the motor is still in car) So you would need to strip it down to bare block anyway.


Still, you should only be set back a little machine cost, new rings and some time. Not that bad of a stuff up.

[royce]

Honestly if you felt your engine needed rebuilding chances are the bore is over size and out of round and youll need to bore it and fit bigger pistons

whoever sold you standard sized brand new pistons should be ashamed of themselves

[zuk85]

Fatzook wrote:

If you didn't bore or atleast hone the cylinders, its probably the cause.

Just like you machine your brake rotors when you fit new pads, or machine a flywheel when you fit a new clutch, you must ensure that the cylinder bores are rounds and smooth before fitting correctly sized pistons and rings.

wait one second before u hone anything!

what your talking about would be blow-by, which is caused from the rings not seating in the cylinder wall properly which would produce a BLUISH- BLACK smoke. not the WHITE smoke he is talking about.= major loss of power too, as gases are all blowing past the piston into the sump and oil the other way..

white smoke is caused from coolant or condensation. but by the sounds of it blowing white smoke all the time now would be the head gasket. and certain gaskets must be put up the correct way other wise it wont seat properly.

have u checked your oil to see what colour it is?

first i would say check you had the right head gasket
& make sure its dosnt need to be up a cetrain way.

[royce]

you cant get smoke from something that cant burn

[zuk85]

i dont mean critise you mate im sure u have way more experience than me.

i have just finish cert II in auto mechanics. so i am fresh and have be taught by teachers who are constantly ungrading with vehicle changes.

it aint burning... its turning it to steam because the explosion in the cylinder is so hot and the already hot water, mixes and creates steam...

[royce]

Steam isnt smoke is it

go dribble some water down your carby with some revs up and watch what comes out and then do it with some engine oil, it wont be blue, it will be far from blue

Seriously, try it, jsut a dribble wont hurt it (the water will actually clean the combustion chambers) and youll learn something they wont teach you in school cause schools only deal with problems in theory, not real ones

[zuk85]

no need to be a smart ass mate did u not read what i just said that when it mixes in combustion chamber is creates STEAM which will off course come out the exhuast with SMOKE from what oil and fuel was burnt.

and im using smoke as a term ok. im just trying to give the guy viable information. it makes more sense that it would be a head gasket with white STEAM/ SMOKE comming out the exhuast.

the only other reason that white smoke could be cause which i do agree with the ring part is that the cylinder wall could be GLAZED which would require honing.

also i use to own a rotary so i know what happens when u pour oil down the carby, not the only bloke on the planet mate.

[steak_knife]

I didn't see smart arse....

[zuk85]

royce wrote:

and youll learn something they wont teach you in school cause schools only deal with problems in theory, not real ones

so i take it your the only one too have dealt with any real problems then. well we all better leave it up too you too solve all the problems on here mate

[zuk85]

i would think rolling eyes and a smiley face after those remarks would suggest smart arse tactics lol

[Bruce]

This just got interesting.

[Scrawny]

zuk85 wrote:

royce wrote:

and youll learn something they wont teach you in school cause schools only deal with problems in theory, not real ones

so i take it your the only one too have dealt with any real problems then. well we all better leave it up too you too solve all the problems on here mate

Don't fall into the trap that now you are qualified you know everything. If you remain teachable you will go much further in this life. Sometimes real life experience far outweighs anything you can learn from a book.

[eldo]

why not try a compression check, problem diagnosed in 10 mins

[Bruce]

Yep I aggree Scrawn. What seems to work on paperwork does not alwyas work in the field.
I see it almost everyday.

[JrZook]

junek wrote:

But definately blows a constant white smoke. (WITH OIL SMELL)

Reread the symptoms zuk85! You may have done your cert but that wont help you to listen to the OP diagnosis. Smoke is smoke, steam is steam im sure tell would have taught u that also.