[urq] Water Cooled Turbos

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In a message dated 2/13/01 7:31:58 PM Central Standard Time, 
jthomascourtney at iwon.com writes:

> Properly treated, the oil cooled Turbo's can hold up fine.  My 84 5KS Turbo
>  has 248K miles and is still going strong with original turbo.  I have heard
>  it suggested that one of the worst things for a turbo is to let the car
>  go undriven for a long period of time as it will lead to pitting of the
>  bearings.  (Any thoughts...)

Anyone who is storing a turbo should fill it with oil and spin the turbo on 
occasion.  Pitting of the bearings?  I suppose anything is possible, since 
you are in effect resting steel shaft on a brass bearing  when the car is 
off, but I haven't had it happen or seen it in my 20years of turbocharged 
goofin.

>    I have had three turbo cars to date (one was a water cooled Dodge 2.2
>  that went 200k plus) and have never had to replace a turbo.  I had a good
>  friend with a 930 (which are notorious for going through turbos) who never
>  had a problem with his turbo, but he drove the car regularly.  BTW we did
>  LA to Mammoth Mountain in that car, in just under 4 hours (including a 20
>  minute chat with Police)but I digress...

I too owned a dodge turbo (GLH turbo TO4).  Beat the crap out of it, never 
failed.  WRT oil vs water jacketing, the advantage is lower hot operating and 
lower shutdown temps at the turbo bearing and the piston ring.  This leads to 
longer engine life.  That said, good synthetics can hold this together for a 
longer term (most likely your experience).  But really, the SAE tests are 
pretty thorough and convincing wrt waterjacketed turbos, they pull over 1/3 
of the heat from the piston rings and center bearings vs a non water jacketed 
turbo (just looking at the audi SAE paper 860103).  That's a tough thing to 
argue against.  The afterrun advantage is pretty easy to argue against IMO

>  
>  Naturally I change the oil regularly, and try not to turn them off while
>  the turbo is still glowing cherry red.  Otherwise, I just drive them often
>  and as hard as local authorities will let me...

But you digress...

HTH

Scott J