200 TQ Hissssssssss....

[Nate Stuart]

> Symptoms are similar to those many of us have seen with a split IC
> hose--except the hose is ok.  If I keep pushing beyond 1.1 bar, I get black
> smoke from the exhaust and the engine begins to stumble.  Sparks plugs,
> W7DTC's, show no significant oily deposits and are light gray at the
> electrodes. When I let off the accelerator the hiss continues for about two
> seconds and slowly dies off, leading me to believe that some component is
> being pressurized and the air is escaping from a small hole somewhere.
>
> So what do you think--small hole in the intercooler?  The ends don't appear
> to be loose.  Perforated WG diaphragm? Some gasket I don't know about?

Try here: http://www.sjmautotechnik.com/boost.html

I'd check ALL the hoses post turbo. Namely the lower turbo to IC hose, and 
the afforementioned IC->TB hose (take it off and very very carefully examine 
it, many of the splits tend to seal themeselves back up w/o any boost). In 
generall look around at all the bits in the intake stream that see bosted 
air. Look for any oily surfaces near any of these parts, in general the air 
after the turbo has a decent amount of oil vapor and will clearly mark where 
it is escaping.

Also check the IM to wastgate hose for any splits (usually this causes 
overboost however).

Good luck!
-Nate
'89 90q
'87 5ktq donor
'86 5kt donor