[Vwdiesel] Cold!

[Patrick Dolan]

I haven't actually looked at the tach when cranking - never assumed it would be accurate (due to voltage sag).  I will start watching now and let you know what we see.  Still on the original battery, BTW.  I have found cranking speed to be VERY important on diesels (at some point, a cold cylinder wall will take away heat faster than it is being generated by compression - to the point of falling below ignition point).  

There are a few things that you can (must) do to get your vehicle to start in cold weather.  Obviously, the oil is right at the top of the list.  The other one is battery voltage (not kidding).  For each design of engine, we found (from being the coldest VW dealer in NA back in the '70s) that there was a threshold voltage, and if the battery didn't show that before trying a start, don't even bother (for gassers then, it was around 10.5 volts).  To get there (wherever that is for our cars) the battery MUST be getting and ABLE to take a full charge.  In cold weather, that means that your battery really needs a blanket - since a cold battery will accept very little charge - and maybe no net increase in a short trip.  You shoud take a voltmeter and check for voltage drop along the cables (including ground - compared with the actual battery POSTS) while cranking.  This will show up any high resistance ground - and don't forget the bonding wire from the battery to the chasis to th
e engine/trans.

Finally, you should do a load test on the battery itself.  This will show up when you are checking voltage at the posts, but you should use a known resistance and compare voltage over time.  Most battery/alternator shops will do this for free, as well as telling you if they think your charge voltage is adequate (I like to see 14.0 - 14.5)

Pat

----- Original Message -----
From: Val Christian <val at mongo.mongobird.com>
Date: Monday, January 19, 2009 4:39 am
Subject: Re: [Vwdiesel] Cold!

> Tachometer...RPMS.  I have a 03 which is a poor starter, 
> regardless of
> the temperature.  At -10F it's impossible.  I've redone the timing,
> trying all kinds of settings, checked the glow system, and replaced
> plugs just for kicks.  As near as I have ascertained, it may be 
> turning slow.  VAGCOM says 183 rpm, nominally.  The tachometer 
> agrees..
> Some postings have suggested that at least 200 RPM is necessary.
> 
> Once it fires up, it runs just fine.  It's just that initial 
> "ignition".
> If I roll it down the driveway, and pop the clutch, it starts 
> right up.
> 
> I'm looking for verification.
> 
> > 
> > BTW: what did you mean by tach reading?  Did you mean odometer? 
> (which was around 20k)
> > 
> > ----- Original Message -----
> > From: Val Christian <val at mongo.mongobird.com>
> > Date: Sunday, January 18, 2009 5:10 pm
> > Subject: Re: [Vwdiesel] Cold!
> > 
> > > Patrick,
> > > 
> > > Mind telling me the tach reading on that 03 prior to firing 
> (like 
> > > short glowing)?
> > > 
> > > Thanks.
> > > 
> > > Val
> > > 
> > > 
> > > > 
> > > > -45 C.  Not me, my wife (2003 Jetta TDI).  Emergency on a 
> day 
> > > when she left the car unplugged since she had no intention of 
> > > driving in that cold.
> > > > 
> > > > ----- Original Message -----
> > > > From: Terry Briggs <vbriggs at stny.rr.com>
> > > > Date: Sunday, January 18, 2009 9:29 am
> > > > Subject: Re: [Vwdiesel] Cold!
> > > > 
> > > > > - 10 with the '79 rabbit
> > > > > On Jan 17, 2009, at 9:54 PM, Craig Osborn wrote:
> > > > > 
> > > > > > How about a little contest?
> > > > > > My 81 PU started today with no block heater when the 
> > > temperature 
> > > > > was 
> > > > > > -4F /
> > > > > > -20C .
> > > > > > What is the coldest temp that any of you can remember 
> > > starting 
> > > > > your 
> > > > > > diesel
> > > > > > without an add on heater?
> > > > > >
> > > > > > Craig
> > > > > >
> > > > > > _______________________________________________
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> > > > > > Vwdiesel at vwfans.com
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> > > > > >
> > > > > >
> > > > > 
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> > > > > 
> > > > 
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> > > > 
> > > 
> > > 
> > 
> 
>