Date:         Fri, 17 Nov 2000 21:53:04 +1200
Reply-To:     Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Subject:      Re: Reliability of turbodiesels
Content-Type: text/plain; charset="us-ascii"

>Haven't heard of any VW TD heads cracking - but maybe I've just been
>lucky. It's
>the turbochargers themselves that seem to be more fault-prone. Keeping your
>engine running on tickover for a bit after a highway run helps cool things down
>and improves life expectancy.

Turbochargers usually have fully-floating babbit bearings, which are
extremely hot during running (especially when the turbine housing's
incandescent). The flow of lubricating oil cools this bearing.

When the engine is stopped while the turbo is still really hot the oil
still in the bearing cooks, depositing a little varnish on the 4 surfaces.
Let happen enough, it gums the bearing up with burned oil and seizes
expensively. This is why all turboed engines should have a turbo-timer
which delays engine shutdown for say 2 minutes, so the turbo cools while
oil is still circulating.


Andrew Grebneff
Dunedin, New Zealand
VW & mollusc nut
1984 Caravelle (currently SVX engine waiting for a trans)
1985 Mitsubishi Galant Sigma 2.0 (FWD)
1986 CE80 Toyota Corolla 1.8DX diesel
1989 CE96 Toyota Corolla 1.8DX diesel van/wagon
1989 CT170 Toyota Corona Select 2.0 diesel