a turbo question. 4m40

[fish]

I have a challenger with the 4m40 turbo. Its always had a bit of a whine to it since I bought it. But ive noticed that lately it has been audible spooling down when shut down. Is this a sign that the end is near?
If so anyone got one for sale? I think I would be capable of replacing it.

[fish]

Its a bit flat on the boost around 2000 too.

[churchill]

I'd take the intake pipe to the front of the turbo off and feel for play in the shaft. I think anything over 0.1mm side to side is considered worn.

[fish]

Ok does that play cause the whine? Does it not spool up ad fast causing the lack of boost.? Ive never pulled one down before. Right now im in the middle of a big road trip back to queenstown. Got the whole of the South Island to go yet so it will have to hold till then.

[zukmeista]

When it gets too much play in the bearings it allows the impeller to contact the housing which would cause a noise. Take the intake pipe off and try and move the impeller side to side while turning it, if it touches the housing it needs to be rebuilt/replaced.

[ClassicCruiserSpares]

Ive seen this problem many times but with pajeros, people waste a lot of time and money replacng or recon the turbo but nine times out of ten its the manifold gaskets. Inlet and exhaust. Check the flange gaskets also while your there.

[Petemcc]

Also dont try too hard to get the impeller to rub on the housing. All turbos have play. They need to as they are normally metal bearings which run on a film of oil so there is room between the shaft and bearing when the oil is not being pumped through. You can stuff the turbo by checking for play too strongly. A turbo rebuilder was telling me the other day about shaft and impeller damage from people checking for play.

Excessive play is bad some is ok. If u are not sure ask a tubo shop.

[slidenyo]

I was informed when I was a kid that is not too much wiggle that is a worry its the in and out float.
so the ability for the impeller to move forward or backward in the the housing.
Pop reckoned too imagine the impellor shaft was made of wood and each stroke forward and back would wittle it, leaving more play