smoke when comin off boost

[mic*]

Owen,

I think your later post is a lot more likely than vacuum in the turbine sucking oil in.

I read the part of the link you reference and i gotta say i dont really buy it. Maybe i just dont understand it. Can anyone suggest to me how vacuum in an exhaust is possible when an engine is running? The flow is always being pushed out the motor - a positive pressure - the whole friggin concept of turbocharging depends on it.

There is a vacuum in the inlet side when idling (and i dont think this car has even been idling too much anyway - 400km...), but oil should not leak unless,

a)oil pressure too high,
b)return blockage, then a)
c)damaged bearing

Sure the pressure differential is between oil & compressor is greater at idle when there is no boost in there, so there is more exertion on the compressor seals, but its what they're designed for. I think most turbo manufaturers are aware that cars idle inevitably.

Incidentally if the pressure is equal either side of the bearing seal, the last place oil will wana go at 80,000rpms is to the shaft, centripetal force is pretty strong.

If someone want to suggest that excessive idling causes more stress on the seals, more grit to flow round the shaft insteada being thrown away from it, and thus the bearings WEAR quicker from the inside out, and fail...

..Ill say its a better thoery and i still want evidence.

If they fucked with oil pressure id be looking at that closely, and change your oil before 10 other ppl tell you to do it too.

But really, who rebuilds your motor and throws you out the deep end?

WHAT A BUNCH OF COCKS!

[o_man_ra23]

Mic, many valid points there. The theory behind the vacuum is that the shaft has inertia. It goes at 80000 rpm, then suddenly the air going into it is cut off almost completely (throttle body closes), and so, it takes time for the turbine to slow down naturally. During this time, it is going to suck air, as it is moving faster than the air can push. When there is minimal air and it sucks hard, you get a vacuum in the exhaust manifold. This is only momentary, but enough to suck the oil. Go and check out a few dynamics text books on inertia, and some on centrifugal fans, and something on pressure differentials, it will all become clear then. Now, the BOV setup will relieve the pressure in the intake, before the throttle body, allowing the turbo to continue spinning longer, and creating more vacuum in the exhuast. If a plumback BOV is used, the turbine wheel will suck air from the intake, before the TB, into the exhaust manifold, relieving the pressure differentials on both intake and exhaust, which allows the turbo to safely keep spinning, reducing lag on gear change, and greatly reducing the vacuum effect on the exhaust turbine.

Hope this helps to explain things better. But you are right, from what is known, that extra oil pressure wont be helping anything.

Cheers, Owen

[acmtt]

Have you just added a catch can setup?
A mate of mine put new turbos on and a catch can with smallish connections. The smaller hoses were causing the pressure to be extra high within the engine.

When following him it was like smoke bombs went off as soon as he got off the throttle.

Simple fix,to throw away his dodgy catch can.
But to find this out he tookit back to the workshop that rebuilt the turbos.
No problems since.

Hope this is your problem and its this easy to fix!

[AE86slut]

I'm surprised that nobody has suggested a dodgy oil drain from the turbo yet. I had this exact same problem when I first put in the CA, with a horrid oil drain line that just allow oil out quickly enough from the core to stop it building up and seeping through the seals into the exhaust housing.
You might want to check it out - it may just be the problem!

[mic*]

I'm surprised that nobody has suggested a dodgy oil drain from the turbo yet. I had this exact same problem when I first put in the CA, with a horrid oil drain line that just allow oil out quickly enough from the core to stop it building up and seeping through the seals into the exhaust housing.
You might want to check it out - it may just be the problem!

Pretty old thread here guys. I think the owner of the problem woulda dug it up if it was still ongoing.

And i think you'll find that a blocked turbo bearing return line has been suggested numerous times. as has checking that the size of his PCV system is appropriate.

Cheers tho.

[sleeker162]

didn't get the oil problem sorted, some bunch of dickheads cut a whole lot of wires under the bonnet, i've tryed to fix it up, but it just stalls constantly, the whole conversion is gettin re-wired over the next week, - new engine loom / fuse box - the lot.
also just purchased a to4e, so im not too concerned with the turbo's atm, tho i will be looking into every possibility on the motor itself ie- catch can, oil pump pressure release valve (they said something about having "shimmed" the release valve)

thanks for all help and suggestions guys... its unfortunate that we have shithouse workshops that dont do their jobs properly.... but what can ya do.

cheers,
jesse

[mic*]

Before you spend too much more i would be putting the car back in their hands, pretending like you dont know anything about cars and telling them not to give it back till it stops smoking or till its accompanied by some reimbursement for their incompetence.

The simple fact is that you havent got what you were led to beleive you would recieve for the money you've paid. They created the problem, its their problem to fix.

[sillycar chick]

This may be a little off topic, but its my 2c worth on your problem...

I have heard so many bad storys and had a few bad experiences before that I have come to not trust mechanics in general. Im NOT judging all mechanics or the ones that built your engine, but the reality is unless you are there 100% of the time watching them build it, you never know what they have done with your engine!

This may not necessarily be the case with your engine, but I have come to learn a lot of mechanics wont take as much pride in the work as I personally would on my own engine. But thats just my opinion. But there are also a lot of good mechanics out there that are trustworthy. It comes down to how well you know the mechanics and the sort of work they normally do.

But hey, if anyone has some mechanical know-how and interest and were going to build an engine at home, i'd say GO FOR IT!! At least that way, you could take pride in your work, you know exactly what has been done and have the satisfaction that you built it yourself! Good luck with your engine....

[mic*]

Hey sillycar chick, where in QLD are you?

Its a sad reality that as the need for an expert increases (like an experienced race engine builder - so you dont have to spend years getting there yourself) so does the opportunity for wankers to portray themselves as such & take advantage of people (insert name of above workshop)

[sillycar chick]

Hey sillycar chick, where in QLD are you?

Its a sad reality that as the need for an expert increases (like an experienced race engine builder - so you dont have to spend years getting there yourself) so does the opportunity for wankers to portray themselves as such & take advantage of people (insert name of above workshop)

Im from Brizzy... and it is sad these wankers exist, I truly feel sorry for all the people out there who send their cars to mechanics, especially the ones who arent mechanically minded and dont even know how an engine works! Too many people get ripped off and end up with a shit engine, and they have a particularly bad attidue to females as well.

So anyway, back on topic, I really hope sleeka162 hasnt had dodgy mechanics working on his engine!