Servicing/Rebuilding turbos

[SimonV8ster]

If there is no particular items to service within a turbo do you just use them until you notice somethings not quite right ?

Apart from an obvious lack of performance or difference in performance what are other symptons of a wearing turbo ?

Reason I ask is that I have just sourced an early MX5 with a turbo conversion on it, believed done since new and now on 140k miles.

Engine doesn't appear to smoke but when I took it up to 5K revs and changed up I saw a puff of smoke from the rear. Is this more likely to be a seal in the turbo going rather than valve seals or something ?

Couldn't get it to smoke when I slowed down by the gears with I thought would have suck oil down the stems if the were worn.

[anonymous-user]

Smoke on gearshifts or lifts tends to come from transient oil pullover as the plenum goes from positive pressure to negative pressure. This usually involves a change from the "full load breather" which is pre-compressor) to the "part load breather" that is plumb'd to the intake manifold downstream of the throttling system. It's not unusual for oil that has been hung up in the non -flowing part load breather to suddenly surge into the manifold - cylinders - and hence be burnt on a rapid tip out.

It could also be the turbine piston ring seal, where the sudden change in crankcase and downstream exhaust pressure (usually neagtive) can cause an unseat and a small oil pull over .


Check the turbo for worn bearings, if these are worn, the sealing system soon degrades as the shaft orbit becomes eliptical.

[ian_uk1975]

Just to add to what's already been said, you can check for worn bearings by grasping the tip of the turbine shaft in the compressor housing between thumb and forefinger and giving it a wiggle. If there's anymore than just a barely perceptible amount of play, the bearings are worn.

[CarlFrederickson]

Dont mess about get down to CR Turbos in New Milton Hampshire