Turbo engine smokey when on overrun?
Turbo Mini Forums

Mini metro turbo'd mini.
Fine under normal driving conditions doesnt miss a beat however, on the overrun there is smoke that comes from the exhaust.
Mixture is fine, recent rebuild, no lip on barrels, rings fine, new stem seals etc..!

So i cant work out what seems to be the problem any advise on what the problem could be?

Also i would just like to apologies if this topic is already up on the forum.

Thanks for your time, look forward to your responses.
Dan.

More Boost, More FUN!

My money is on the turbo oil seals. Also check your valve stem seals havent come off their seat.

If something is worth doing, it's worth doing half of.

Right, whats the implication of the turbo seals then?

More Boost, More FUN!

Turbo seals for sure. Implication? Well, it'll continue to smoke. It will likely get worse, but if it stops smoking then it's probably because your engine has stopped or its run out of oil.

Could be worn valve guides to. The oil will get sucked down under vacuum on overrun.

WWW.TURBO-MINI.COM

as others have said, could be stem seals, rings but most probably turbo seals. if its the turbo seals then it will get worse, normally to the point that you pull up at traffic lights and the cloud of smoke seems to catch you up and waft past.

If its only doing it on the over run I agree with phill, If the engine has not been rebuilt then you may find your guides are past there best, take the plenum off and look for oil in the top of the neck or on the joining hose.

Edited by Mr Joshua on 28th May, 2009.

Own the day

Thanks for everyones reply been helpful. Got an idea on the price of a turbo re-build anyone?

More Boost, More FUN!

or take the turbo off and try it n/a

How'd you mean? To see if it still smokes?

More Boost, More FUN!

Yes, that would either confirm or eliminate the Turbo.

WWW.TURBO-MINI.COM

your Turbo seals are GOOSED ! most likley
but dont overlook the guides as well
and dont discount the ring lands failing on the pistons
what pistons are in there ??

Pistons was the only thing I didnt replace on mine, and guess what it was, lol, pistons!
Shane

imo when its the pistons it tends to smoke a bit all the time and smoke more under load and especially when on boost. this can also be proven with a compression test.

valve guides or seals tend to make it smoke on over run but then so does the turbo seals. in my exp the turbo seals tend to go at the same time as the bearing, or the bearing goes making the seal fail, either way check the turbo shaft for play

If it's only doing it on overrun, it's NOT the pistons/rings.

if your breather aren't connected , you can first try this. It can help a lot oil seals.
When you're on overrun, your turbine is reving, your throttle is closed, and so seals are seing a high vaccum, so oil passs thru.when breather are connected, the vaccum is seen by the crank case, so your valves guide and turbo seals too.

Right, once again thanks for all the responses! The pistons are new and so are the rings the head was flowed and ported. Dont know whether guides were replaced but i know the stem seals were. Also had double valve springs in it. And last month i had the head off and the barrels are fine which eliminated me thinking it was the rings or pistons and the fact it only does it on the overrun.

The previous owner said he checked the turbo for any play and said there was none. (In fairness i understand he was selling it but i do trust him).
So i guess its either guides or turbo seals.

Whats the rough price of a turbo rebuild? Anyone also reccomend someone to do it?

Thanks.

More Boost, More FUN!

To port the head properly the guides need to be removed. So unless they were stupid enough to fit the old guides again, they should have been replaced.

WWW.TURBO-MINI.COM

Right well i shall speak to the bloke i bought it off about that...

More Boost, More FUN!

well any of the above how ever when my lands broke it was the same ran well, didnt smoke untill the over run when they were cracked, when the lands broke big style then she smoked like a barsted, how ever if the rings gaps are way to big like those crappy mega set i got this will also cause smoke on the over run as when on the over run oil gets dragedd past the rings, but start with the easy stuff first, then do a drop down test on the cylinders

always looking for them bigger bunches of bannanas