chipped 1.8t and diverter valves

AudiBiTurbo at AudiBiTurbo at
Sat Apr 14 09:08:18 EDT 2001

The Bosch diverter valves have been failing on the VW and Audi turboed cars 
for some time.  Mostly a slow failure mode, or said another way, the valves 
are "slow" to react.  Basically, when the valve fails, it can let your turbos 
overspin and mildly overboost your engine (long term negative effects).  If 
the valves are sticking further, it can accelerate this wear and overspeed of 
the turbos.  It has been suggested that the turbo failures on the 1.8T engine 
are a direct cause of bad bypass (diverter) valves, but without a boost 
gauge, you'd never know what's going on.
It's a particular problem in the 225 HP Audi TTs.
I recommend to all of my customers which own 1.8T or 2.7T engines to replace 
these valves, weather they have stock or modified engines.  If nothing else, 
peace of mind.  Personally, I sell (and run a pair on my 2000 S4) Bailey 
valves.  Forge valves are another alternative.

Mark Rosenkrantz
AudiBiTurbo at
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