Re: Hydraulic Lifters

[robertr@apertus.com (Robert Randall)]

> 
> I'm sure this is old hat for most quattroeurs, but I'm unable to find the 
> answer in the faq.  Here is my question:  how serious is that 
> clickety-clack sound at startup?  Do you just live with this?  Do you 
> change the oil viscosity?  Are the valves adjustable?
> 
> My wife and I were test driving an 89 100Q (73k miles) which made this 
> sound at startup.  Otherwise the car is fine, but this sound is unnerving, 
> especially to my wife who is used to the vanilla characteristics of her 
> Toyota.  I appreciate any responses.
> 
> Merrill Hoekstra, digest mode
> 

The noise is likely to be the hydraulic cam followers.  This is the overhead cam
version of a hydraulic lifter.  Most folks on the list refer to them as 'lifters'
and not cam followers.  The hydraulic cam follower uses engine oil pressure to 
adjust valve clearances dynamically.  This is opposed to standard valves that require
manual adjustment as surfaces wear down.  The good news is that you never need
to adjust your valve clearances.  The bad news is the hydraulic cam followers
can and do wear out.  Hydaulic cam followers due require a certain amount of 
time after start-up to work properly.  They need to come up to pressure.  If I
recall from the Bently manual this latentcy is about 2 minutes.  

If the car never exhibits the noise after a short warm up period I would not
worry about it.  The cam followers are doing their job.  If however, after a
warm-up run you can still hear the noise... 

Try revving the engine slightly, up to about 3k rpm and letting it drop back down.
If you can still hear the clickety-clack then the cam followers need to be
replaced.  If they do and you don't do any performance mods at the time of 
replacement (unlikely? :-)) your looking at $200-$300 (parts and labor if memory
serves me).

Hope this help.  (hey, experts out there, if i'm blow'in smoke let me know,
but try to be kind...)

Regs,
Robert.


Robert Randall			robertr@apertus.com
86 4kcsq (arrest me red)
86 jetta gli (a tame silver)