[Vwdiesel] Head/Valve work question

[James Hansen]

I scruffled around looking for a good picture of a cam, which I didn't find,
but here's one that is sort of okay...

http://www.2carpros.com/articles/how-camshaft-variable-valve-timing-works

scroll down to the variable cam timing section.  Ignore the variable thing,
but see how the highest part of the cam lobe rests on the follower (the nose
of the cam)?    It doesn't actually sit flat on the follower, it has a
slight taper, so that the outer edge hits the follower first, making the
follower spin as the lobe wipes across it.  The picture doesn't show that
exactly, but I think you'll see what I mean.  The rotating bit is to extend
wear, introduce lubricant to the interface more readily, etc...  If the cam
nose gets worn flat (wrong oil, dirty oil, breakdown of the additive
package, insufficient anti-shear additives, too narrow a cam lobe, etc...)
the follower has nothing that makes it turn in it's bore as the cam goes
past, and can wear a cam noseprint in the follower.
-james



-----Original Message-----
From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com] On
Behalf Of Dave Cook
Sent: May-24-11 6:18 AM
To: VW Diesel Group
Subject: Re: [Vwdiesel] Head/Valve work question

Mark: I'm not sure I understand what you are saying here.  Could you please
elaborate?

James:  Unfortunately, I had the cam off when I delivered the head, and the
guy had the followers out before he noticed the "grooves" or at least he
couldn't tell me for sure which ones were not rotating.  Is the "nose" of
the cam just the pointy bit that pushed down on the valve to open it?  Or
should that be rounded off or something to make the follower rotate?


Dave Cook


--- On Tue, 5/24/11, mark shepherd <mark at shepher.fsnet.co.uk> wrote:

> From: mark shepherd <mark at shepher.fsnet.co.uk>
> Subject: Re: [Vwdiesel] Head/Valve work question
> To: "vw fans" <Vwdiesel at vwfans.com>
> Date: Tuesday, May 24, 2011, 9:27 AM
> Also simply try moving  with
> finger with cams TDC exhaust stroke
> 
> Mark
> 
> 
> ----- Original Message ----- From: "James Hansen" <jhsg at sasktel.net>
> To: "'Dave Cook'" <davevw at yahoo.com>;
> "'VW Diesel Group'" <vwdiesel at vwfans.com>
> Sent: Tuesday, May 24, 2011 9:36 AM
> Subject: Re: [Vwdiesel] Head/Valve work question
> 
> 
> 
> Be certain that your cam isn't also flat Dave. The nose of
> the cam should
> have some slope to it, so as to rotate the parts
> below.  A lot of times if
> things stop turning, it's because the cam is worn, and is
> flat on the nose.
> Compare the lobes that have turning bits to those that have
> grooved
> followers.
> -james
> 
> -----Original Message-----
> From: vwdiesel-bounces at vwfans.com
> [mailto:vwdiesel-bounces at vwfans.com]
> On
> Behalf Of Dave Cook
> Sent: May-23-11 9:54 PM
> To: VW Diesel Group
> Subject: Re: [Vwdiesel] Head/Valve work question
> 
> I don't think they were "clacky" I never heard anything
> unusual with the
> engine running, and I have spent a lot of time driving the
> car and riding in
> it.
> 
> So maybe just replace the two...?
> 
> Dave Cook
> 
> --- On Tue, 5/24/11, LBaird119 at aol.com
> <LBaird119 at aol.com>
> wrote:
> 
> From: LBaird119 at aol.com
> <LBaird119 at aol.com>
> Subject: Re: Head/Valve work question
> To: davevw at yahoo.com
> Date: Tuesday, May 24, 2011, 1:45 AM
> 
> Ouch! I've only replaced broken or clacky ones. Clacky I've
> learned, if
> there are
> 
> more than one or two, replace them all! Broken, just the
> broken ones. I'd
> classify
> 
> yours as "broken" and probably just replace the problem
> ones, unless there's
> an
> 
> issue and they TEND to go bad, then do them all. There's
> always that really
> cheap
> 
> vw parts guy... proth? Chinese but some of that is ok.
> 
> Loren
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