[Vwdiesel] Much ado about nothing? (fwd)

[Val Christian]

> For me I've travelled only 40000 miles in my Quantum over 3
> years. During which I've replaced one head and about 12
> glowplugs.
> I had 3 go a few weeks ago after a year of  trouble free
> starting.

	In my (limited experience), frequently failing glow
	plugs are signs of other problems.  Don't let the GPs
	distract you.  There's something else which is the 
	root cause.  The relay/timer, the injectors, and
	intake oil ingestion are frequent causes.  Other 
	causes I've seen include intermittent fuse blocks
	and power feed to the fuse block/relay sockets.

	On the matter of how often glow plugs fail, here's my 
	experience.  First, I have owned and driven quite a 
	few A1s and a couple of A2s over the last 27 years,
	all diesels.  Probably close to 2,000,000 total miles
	on the "fleet" under my care.  I have a box of functional
	and questionable glow plugs in the shop.  Probably 20
	or so.  I estimate that I've thrown an equal number out
	for obvious problems.  That works out to a glow plug 
	per 50,000 miles.  Taking a different estimation approach,
	I would offer that I seldom change glow plugs, except 
	isolated plugs, on my "new" cars, which I'll loosely
	define as those with 100Kmiles or less.  It's always
	the older cars, and the cars with some kind of problem,
	which go through any number of glow plugs.  That's just
	my experience, and most of it loosely estimated.  

	Let me put it another way, if you're going through altenators
	frequently, then you have a problem.  I find that on my
	A2 (where I continuously run AC and ham radio equipment, and 
	the headlights), I need new brushes every 40 to 60 kmiles.
	I've had similar experience with my A1s, where there was a 
	high electrical load.  The ones with light loads might go 100K.
	The bearings don't go, just the brushes.  That seems normal
	and reasonable (but it would be expensive if I wasn't a 
	DIY).  If all of the sudden I was going through brushes
	at 10Kmiles or 20Kmiles, I'd be looking for another cause.

	If your glow plugs are frequently failing, you have a problem,
	and it probably isn't the glow plugs themselves.


> After the recent GP failures I decided to do something about
> it as removing fuellines and then retorquing the fittings
> can only lead to failure over time.
>  (If a set costs $100 over your way I'm sure they'll cost
> twice that here) :o(

	Again, in my (limited experience), I've only had one
	fuel line set have a problem, and that was my fault.
	I didn't have the lines perfectly aligned, and used
	torque to make the fitting work.  It leaked a teaspoon
	of fuel every 2000 miles (as a matter of estimation
	judging from the staining).  Ultimately, lapping the 
	tubing fixed the problem.  When my cars go to the crusher,
	I tend to keep fuel lines.  I can't remember needing any
	of them.

> My recent addition to cure the problem is another switch to
> turn off GP's as soon as not needed.
> switching back on gives further possible 45 second heating
> should it be required.

	Why not just go to a totally manual switch, if you think
	you're having timing problems.  Cut up an old relay,
	and use a foglight switch to activate the relay.  That
	way you can keep all the wiring intact.  You could
	still work backwards, and install a regular relay/timer
	after you resolve your problem.  Or you could just use a 
	switch.  I did this with one of my early A1s, which went
	through relays, back when there were relaibility problems,
	and the price was outrageous.  

> I have the option to leave GP's off if engine still warm...
> Mark(The Miser)UK

	You'll find out that with a lukewarm engine, 3 to 5 seconds 
	of glow means you'll probably start with a very short "tap"
	of the starter.  The choice is yours, but in general, I'd
	rather run plugs a little to save wear and tear on the starter.
	I've had several 300K mile plus cars, and none have gone through
	starters.  Glowplugs are cheaper.

	[Ironically, one of the early evaluation criteria points in my
	initial decision to buy my first VW diesel, was the up front
	easy access to the starter motor.  I had replaced a couple 
	starters in other cars, and figured that with a diesel, I was
	likely to replace the starter more often.  Not so.  However,
	on my compact diesel tractor, I've replaced the starter motor
	brushes twice (Hitachi starter) in about 2500 hours.  Go figure.]

	Val