Re: '98 A6 2.8 won't start- mechanics are at a loss...

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <l03020900b3daf04c124a@[194.134.63.3]> Tom Nas writes:

> All systems check out, no fault codes. Fuel and spark verified, timing belt
> OK and not jumped a tooth. When you start it, it turns very quickly as if
> there's no compression (which is OK when tested, BTW). Not even an attempt
> to start, nothing.
>
> My first impression: plugged exhaust/cat. Any other suggestions?

Oil overpressure.  Attach a manometer-style gauge in place of the G10
oil pressure sensor and compare base engine oil pressure with nominal.

(Excess pressure causes higher than normal flow into the hydraulic
 lifters.  This becomes extreme as engine rpm increases, expanding
 the lifters and dumping compression - engine spins like a turbo.)

--
 Phil Payne
 UK Audi quattro Owners Club
 Phone: 0385 302803   Fax: 0870 0883933