Turbo shaft play...

[MidnightBlueS2]

Hi everyone,

While dismantling my exhaust to fit the stock exhaust back on ( stupid Belgian laws won't let me pass MOT without my cats ), I checked the hotside turbo shaft and whaooow, 15000km since fitted from new and already about a small mm of play in the turbo shaft

Phoned Doug right away at MRC and he says that it's perfectly normal and not to worry... Said it's because it's not a ballbearing turbo and the turbo was completely cold also when I checked it. Said that when oil is flowing and the turbo is hot, there wouldn't be any play...

Of course, I can't check this when the turbo is scalding hot and the engine is on...

Any can confirm / infirm ? Turbo is still under warranty so....

Many thanx !

David

[JP]

It's natural for a journal bearing turbo to have sideways movement. So long the blades dont touch the housing. Time to start to worry is when there is in and out movement from worn thrust bearings.

[MidnightBlueS2]

It's natural for a journal bearing turbo to have sideways movement. So long the blades dont touch the housing. Time to start to worry is when there is in and out movement from worn thrust bearings.

Good to hear !

Why is this ? Sorry, I'm not familiar with what "journal" bearings are...

[MidnightBlueS2]

Bump

[MidnightBlueS2]

So no one else can help me on this one ?

[SteveH]

The lateral shaft movement is there because there is no oil pressure when you have tested for play. The shaft floats in the pressurised oil when the car is running.

[JP]

^^^^^ as he said. A Journal bearing is made from phospherous bronze like your valve guides. So they need to have a minor amount of play to allow the shaft to rotate. Once you apply oil pressure the shaft rotates on the thin film of oil. Whereas if you have a roller bearing turbo the bearing consists of a ball race so now the bearing is interference fit to the shaft where the play is that of the race itself. Advantages of the roller bearing turbo is less friction quicker spool up over the journal bearing. The dissadvantage is when they blow it is bin time whereas a journal bearing turbo can be potentially rebuild if you haven't done too much damage.

[MidnightBlueS2]

Thanx guys.