Blown Turbo

[Biturbo18]

Hello everyone,

Can anyone help me or give me a hint about how to check for a blown turbo? or atleast give me some "symptoms" of one?

Because I recently rebuild a 1985 Maserati Biturbo 2.5L engine, and on start-ups it creats smoke; however in about 10 mins it stops smoking but once the throttle is pressed and the engine revs past 2000rpm's it begins to smoke again. I was thinking that it might be because the engine is not broken in yet, or also becuase of alot of oil deposit in the catalytic convertor, since before the rebuild the oil seals were bad and the valves allowed oil to leak down into the pistons....eventually clogging up the catalytic convertor.

But I also read on one of Maserati's forums that if the engine makes a lot of smoke it might be because of a blown turbo...so if anyone can help me, or atleast give me an advice, that would be great! Thank you!

[UncleBob]

from the sounds of it, you haven't ran it much, and as you say, if there is a lot of oil (or any, for that matter) in the exhaust, it will take a bit to burn it off.

Before I recommend taking the car out and beating the snot out of it, there's a couple things you can check. Make sure your turbo oil lines are routed properly. a restricted return line from the turbo can cause the same problem (oil pumped into the exhaust). I would also suggest pulling an intake inlet pipe and see if there is oil saturation from the turbo.

If all that checks out, take it for some aggressive driving to clean out the exhaust. It should clear up within 15 minutes of hard driving. If it doesn't, then you know something is messed up.

If its white smoke, its from the turbo. If its blue smoke, then its going through the combustion chamber and is more likely to be from the engine.

Hope that helps.

[Biturbo18]

alright thanks for the tip...yea I guess first we are gonna drive it a bit, then well see, if it still is smoking we are gonna take of both turbos and clean them out or possibly rebuild them.

yea thanks again

[KiwiBacon]

To add to Bob's suggestions.

The seals in a turbo are more like piston rings. They let a small amount of leakage past.
In normal operation the exhaust and intake sides of the turbo have more pressure than the turbo housing (which is vented to the crankcase through the drain). So you get a bit of intake air and exhaust gas through the turbo seals and into your engine crankcase.

If the drain gets blocked you get more pressure in the centre housing than the exhaust or compressor. So you get engine oil blown into the air intake and/or exhaust which creates a lot of smoke.

If your throttle is upstream of the turbo, then you'll have a real seal (carbon face sort) on the compressor side to stop the intake vacuum from sucking oil from the turbo.