Oil leak from head gasket / oil filtration

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

In message <876211372.1124236.0@dboyd.demon.co.uk> David Boyd writes:

> Can anyone please offer an opinion re my '91 Audi 100 1994cc engine
> code RT, which has started to weep oil from the head gasket just
> above nos. 4 and 5 cylinders on the radiator side of the block. It is
> more a slight seepage than a leak, and is probably the result of
> starting to use thin synthetic oil  - the cam cover gasket is also
> leaking a little. Should I just leave well alone or is the head
> gasket likely to fail unexpectedly. The Archives had a fairly
> inconclusive  discussion about re-torqueing (that's a queer word to
> spell, hope it's correct) the head in such circumstances.

Has the head been off?  This is one symptom of a bolt failure, fairly common if 
the bolts (which should be discarded when removed) are re-used when the engine 
is reassembled.  Since you have a cam cover leak in any case, it would do no 
harm to remove the cam cover and check the head bolts on that side of the 
engine.  Use a proper triple-square driver, NOT a TORX driver.  In theory, you 
shouldn't tighten the bolts - but there's nothing stopping you replacing them 
_ALL_ with a new set (around a pound each) without lifting the head.  Tighten 
crosswise from the middle to 40Nm, then 60Nm, then 180 degrees.  Fit a rubber 
cam cover seal (from AM Cars?) when you replace the cam cover. 

The main danger, BTW, is the head warping.  Fix it.

> BTW, I noticed a firm here in the UK is marketing a device which
> seeks to keep metallic particles suspended in the oil in the filter,
> by means of a fabric belt rather like a bandolier containing powerful
> magnets, which straps around the filter cartridge. The publicity
> 'blurb' states that filters can only trap metallic particles down to
> so many microns, but the magnets can hold the smaller ones which get
> through. A test of this, they say, is to fill a jamjar with used oil
> and then attach one of the magnets to the lid, shake it about and see
> all the metallic gunk attach itself to the lid............seems very
> plausible and a good invention, but one wonders why it's not been
> done before, if it's so effective - any views from those immersed in
> (or should it be lubricated by) oil technology ?

Get a refridgerator door seal from your local council tip, strip out the 
magnet and wrap it round the filter.  Secure it with a large Jubilee hose 
clip.  Audi fits a magnet as standard inside some rear differentials.

-- 
 Phil Payne
 Committee Member, UK Audi [ur-]quattro Owners Club