Cures for sticky lifters? '87 4kcsq

[isham-research.freeserve.co.uk at pop.pol.net.uk]

> i don't know honestly...  drive the car and let it warm up
> thoroughly...  i am using mobil 1 15w50 in my 4kq..  the lifters are
> a bit noisy from time to time..  i should replace them...

> but after warming the engine it seems to end all lifter noise.  make
> sure you don't run the car hard and shut it off..  this seems to make
> the noise worse and last longer after the next startup.

There's an official test - I think it's engine warm and 3,000 rpm for
two minutes (or is it 2,000 rpm for three minutes?) to make sure the
lifters are pumped up.  From an engineering point of view, it doesn't
matter if they're noisy at idle - it's what they do at higher rpm
that matters, and they have to be pretty damn bad to cause problems
then.

If only one lifter is noisy, the noise is often cyclical.  The reason
is that the cam lobes touch the lifter surface slightly off-centre -
this rotates the lifter to distribute the wear.  You can see the
marks on the tops of the lifters.  The noise is cyclical because the
lifter is fed with oil from a hole on only one side of the head.
This oil runs round a groove in the side of the lifter and into a
hole.  When the two holes are facing each other, the oil going into
the lifter doesn't have to force its way round the groove - both
pressure and flow are better, and the lifter is more easily pumped
up.  As it rotates, the holes get further apart and the oil path gets
longer, so the lifter isn't pumped up so much.  This is no problem if
the seals inside the lifter are still good - there's more than enough
oil supply to keep it up.  If the seals are worn, there might not be
enough to do the job and the lifter will partly collapse, causing a
tick.

There's a very good cross-section of a hydraulic lifter in the V8
service documentation - I wonder if anyone could put it on a web site?

The cycle is a few seconds - perhaps around five.

If only one lifter is doing this and you want to change it, take care
to stop the engine when the lifter is at its quietest.  When you take
the cam out, the suspect lifter is the one with its supply hole
closest to the head's feed hole.  I've also found that listening very
carefully to the side of the cam cover using a screwdriver as a
stethoscope and marking the side of the head is a very good way of
identifying a bad lifter.  Audi's test requires you to push the side
of the lifter down with a plastic instrument and judge whether you have
significant movement before the valve opens.  Not always easy.

Just recently I've been 'testing' lifters.  If you take a lifter out,
you can easily pull the internal piston down and push it back in to
feel how tight the seals are.  I tried to do this a few years ago
using pliers but never got anywhere - now I use a small strong
magnetic pick-up tool.  If you turn the lifter so the supply hole
points downwards, you can also pump it to get all the old oil out.
YEUK!!

WARNING - this paragraph is unfounded speculation.  The oil feed to the
lifters also serves to lubricate the sides of the lifter.  If the seals
go inside the lifter, does the oil flow through the lifter increase to
the point that oil pressure around the sides is reduced?  I wouldn't
think it enough to do this, but it's worth a thought.

The magnetic pick-up tool is also the easiest way (by far) to get
the lifters out of the head.  I use a Sykes-Pickavant one with a narrow
pick-up magnet - it's much more useful for ferreting down spark plug
holes than the ones with wider magnets.

On a 'black sludge' engine - one that has seen few oil changes or
inferior oil - it's a good idea to poke out the feed holes while the
lifters are out.  The best thing for this is strimmer ('weed
whacker') plastic wire, but it needs to be the very small diameter
sort.

Also - certainly on the MC/MB/1B engines - I find that ticking is
minimised by filling with oil to the second line of dots below the
'Max' mark on the dipstick.  I don't know why this should be - it
doesn't seem to affect oil pressure.

There's a similar cyclical tick phenomenon with solid lifter engines.
This time it's usually caused by a piece of sh1t under a shim - you
can spot it via the shim wear pattern.

One worthwhile check on all lifter types is the wear pattern where
the lobe bears on it.  Any asymmetry should be investigated.

[snippage]
> the Audi filter is the ONLY filter with a nice little meshtype filter added..
[snippage]

Also the pressure relief valve has the correct spring strength for
the engine and there's an anti-drainback valve.  I cannot understand
people trying to save $5 every five thousand miles and taking risks
with cheap filters.  It's not even worth the time to think about it,
let alone do it.  I've also got my Audi dealer trained to put a new
drain plug crush washer in the box without me asking.

--
 Phil