[Vwdiesel] Cold starting with bad compression

Thu Jan 20 11:38:45 EST 2005

Other good cold WX points.  Thanks.

During the coldest weeks of winter, I see little problem running
5W30 oil, which is commonly available in SI formulations.  If you only run it
for 2000 miles or so during the cold WX, and then change it out, your
engine will never know (grin).  The lighter vis will help starting,
and if it's really -35C outside, the engine will seldom get to full 
operting temp anyway.

An engine with lots of blowby will have dirty oil, and as my tribologist
friends say, a quart of oil holds a pound of dirt at 80F, and less
than a tablespoon at 0F.  So this is a case where cleanliness is 
close to goodliness.  (or something like that).   

I used to run 20W50 year round, for over a decade.  Then another tribologist 
told me that the higher vis oils tend to aggrivate sticking rings, and
therefore more dirt inducing blowby.  (soot is included in dirt, for this 
discussion.)

We sometimes do it in aircooled engines, but for extreme cold, draining
the oil, taking it indoors, and then heating it prior to insertion in the 
engine is OK as well.  Marine supply outfits have various tools
which "suck oil" out of the engine.  These won't get everything out,
and the plastic sucker lines may be stiff in extreme cold.  On airplanes,
we just run a hose to the quickdrain, and the oil dumps into a bucket.
It can be heated on a campstove prior to engine start.

Also, when you're stuck with think oil, and want a temp fix, consider 
playing a propane torch on the oil pan.  It will take a while to 
warm things up, and you want to move the flame around.

Val

> 
> Dunno if you've done an oil change yet...
> 
> Manuals call for 15w40 oil for temps above -15C (about +5F).  Below that
> temp, you should be using a much lighter weight oil which will result in
> faster cranking speeds and reduced starvation at startup time.  Even back in
> (relatively) balmy Toronto ON I noticed significant differences in cold
> weather cranking speeds.
> 
> Lotsa folks use Shell's Rotella oil -- 15W40 dino oil for moderate temps,
> and 5W40 synth when the bottom drops out of the thermometer.  Crappy Tire
> sells 4litre containers for about $15Cdn and $30Cdn respectively.  If you
> were to do oil changes at 4month intervals (5W40 in Dec-Mar, 15W40 for the
> other 8month) your diesel would be very happy.  The only way to make him
> happier would be to use the 5W40 synth all year round.  Lottsa folks also
> swear by Mobil 1 Delvac and others are Amsoil enthusiasts.  IMHO, if you
> were to use any quality oil (say CF level or later) you're at the point of
> diminishing returns.
> 
> Filter should be changed with each oil change.  Stick with the OEM quality
> filters (Bosch, Mann, Mahle) and avoid the junk (Fram etc.).  There have
> also been discussion threads regarding bypass filters and Hagar's famous
> Hillbilly Blotter Testing resulting in REALLY long oil change periods, but
> I'm not gonna open this one again <snicker> but he just did!!! </snicker>.
> 
> My '91 Jetta TD has a block heater and battery warmer.  An hour of this in
> the coldest weather (-35C is not uncommon during winter in Temagami ON) and
> the little beastie lit up within a couple of seconds.
> 
> rgds, g.
> 
> ----- Original Message ----- 
> From: "Smith, Michael" <Michael.Smith at rvh.nb.ca>
> To: <vwdiesel at vwfans.com>
> Sent: Thursday, January 20, 2005 04:26
> Subject: RE: [Vwdiesel] Cold starting with bad compression
> 
> 
> I am an absolute diesel newbie, so take this FWIW, but twice this week I had
> to boost my "new" 1986 Golf.
> IT has a new big battery in it and was rolling over quick enough to start
> any gas engine.  A quick boost with my Pathfinder
> and it started within 10 seconds.  Just that extra few RPM in rolling over
> speed seemed to make all the difference.
> 
> Car is back in the shop, so I haven't done ANY testing yet AFA GP's,
> compression, etc. so I don't know the real state of the engine, but
> the speed at which it rolls over seemed to make a huge difference in getting
> it started.
> 
> Both days it was -15*C -> -20 *C......I think it would start on it's own
> down to about -10*C (just a guess)
> 
> Mike in NB
> 
> > -----Original Message-----
> > From: vwdiesel-bounces at vwfans.com [SMTP:vwdiesel-bounces at vwfans.com] On
> > Behalf Of James Hansen
> > Sent: Wednesday, January 19, 2005 11:13 PM
> > To: vwdiesel at vwfans.com
> > Subject: RE: [Vwdiesel] Cold starting with bad compression
> >
> > you are absolutely correct Andrew.
> > My 89 Jetta td when I sold it had 550000kms and still started to -25C
> > first
> > try.  Only change from stock was timing a tad advanced, and break pressure
> > an extra 10 bar higher.  Compression was way off already, but mileage was
> > good, oil consumption less than a liter between changes.  It also lived
> > the
> > italian tuneup.  regular oil changes with rotella T 15-40 in sumer, 0-40
> > in
> > winter.
> > I think atomization has a lot to do with it, but cranking speed also has a
> > lot to do as well.  faster cranking speeds give a higher combustion space
> > temp when starting.
> > -James
> >
> > -----Original Message-----
> > From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com]On
> > Behalf Of Libbybapa at wmconnect.com
> > Sent: Tuesday, January 18, 2005 6:14 PM
> > To: vwdiesel at vwfans.com
> > Subject: [Vwdiesel] Cold starting with bad compression
> >
> >
> > I have heard it said by many people that if the compression is bad on a vw
> > diesel it will never start in the cold.  I think that glow plugs are
> > essential,
> > but many volks ignore injectors, which may have as much to do with it as
> > compression.  I recently redid the injectors in my 86 n/a jetta (managed
> > to
> > crack
> > the injector bosses in the process due to corrosion).  I did lots of
> > thinking
> > about repair, and then finally decided to try to torque the new injectors
> > in
> > there anyway.  They've held for 2 days so far.  Before installing the
> > rebuilt
> > injectors, I did a compression check.  280, 320, 420, 320.  How about that
> > for
> > s**tty.  Poor little engine has 295,000 miles on it.  The blowby is
> > impressive.
> >  Even without piching the vent hose, the loosened oil filler cap will
> > dance
> > around nicely.  I'm wondering when I get the excitement of a runaway (I
> > hope
> > my
> > wife isn't driving).  Anyway, this morning it was 16°F and I went out and
> > vroom, she started right up with no block heater.  when the glowplugs
> > cycled
> > off
> > she wobbled, but came out of it fine.  I want to see the single digits,
> > and
> > give her a try.  Glow is key, and atomization is key.
> > Andrew
> >
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