On Sat, 04 Dec 2010 10:21:04 -0000, R C Nesbit > wrote:

>The 156 doesn't.

This isn't always trivial to diagnose on a decent common rail diesel
like these units. My 2.4 popped a warning light on the dash when a
couple of the glow plugs failed but other than that, I couldn't tell.
There was absolutely no sign of hesitancy on cold starts that you
might expect from a couple of cold cylinders. Fuel atomisation is
often sufficient just due to the pressure of the injection system to
allow easy starting in surprisingly cold conditions without
pre-heating at all.

Rather than starting sharply, a cold diesel that needs heat but is
without heat would build up revs on the starter motor before firing
cleanly on all cylinders. This can sometimes take a good (continuous)
while on the starter motor while you effectively build up cylinder
heat via just the compression developed by the pistons and air alone.
I don't know how robust the field coils are on modern diesel starter
motors however. In olden times it was necessary but these days that's
only the case when there's a fault condition.

If forced to guess and the car has done over 50-60 thousand miles or
over 5-6 years old, I'd get an Indy garage to replace all the glow
plugs without giving it too much thought. I saw Alfa quote about
110UKP(!!) each (a few years ago) but my Indy sourced perfectly
decent replacements for under a tenner each. These were fine until I
sold the car over 2 years later so ignore scare stories on the
internet about them. You'll need a 'decent' Indy for peace of mind as
a cowboy might well not replace all but charge you for total
replacement (which is where I think some people get problems so soon
after 'cheap' plugs are fitted at some Indies).

--
Z
Scotland
Alfa Romeo 156 2.4JTD Veloce Leather (sold)
'Oil' be seeing you..
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