Subject: LRO: Re: Stalling/Rough idling SIII

From: "C. Marin Faure" <[email-masked]>
Date: Tue, 15 May 2001 00:35:14 -0700

Date: Sun, 06 May 2001 12:39:56 -0400
From: "KURT W. KRAUSS" <[email-masked]>
Subject: LRO: Stalling/Rough idling SIII

>When it starts, it puts out a white puff of smoke.  This always happens,
when starting cold or warm.   It did this before the new head gasket was
installed.

Just got back from vacation and read this, so you probably already have a
bunch of helpful answers.  As I'm sure you know, white smoke generally
indicates coolant getting into the cylinders, usually via a failed head
gasket or cracked block.  However, this usually continues the whole time
the engine is running.  The only reason I can think of that you would have
only a brief coolant leak with its associated white smoke is if the leak is
very tiny, and as the cylinder heats up, the crack closes.  A bit of a
stretch this, but possible.

I operated a Caterpillar road grader on a ranch in the Rockies back in the
mid-1960s.  It was a diesel, but it was started on gasoline.  You'd run the
thing on gas until a certain head temperature was reached, at which point
you switched it over to diesel.  I recall that for the first several
minutes after it was switched over, the exhaust was pure white.  Then it
gradually turned dark gray and then pretty much went away altogether.  I
don't know what caused the exhaust to run white at first (this was normal),
but perhaps there's something there that could relate to what your engine
is doing.

Of course, it is normal for a gasoline engine to emit white "smoke" when
first started, particularly on colder mornings.  This is steam, and
gradually fades away as the exhaust system warms up.  But it doesn't sound
like this is what you're seeing.

It is VERY normal for a Series engine, even when they were brand new, to
start with a puff, sometimes a BIG puff, of blue smoke.  This is because
the seals around the valves are basically worthless even when new, and with
the engine's sloppy tolerances, oil easily seeps down the valve stems and
pools on the pistons.  When you start up, all this oil burns away with the
blue cloud most Series drivers are familiar with.  It should go away after
a few seconds.  If there is coolant getting into the oil that seeps down
into the cylinders after the engine is switched off, I suppose it's
possible the startup puff could be white, not blue.

A reliable and simple way to judge if your engine is running right is to
look at the inside of the exhaust pipe after a normal drive.  Not a short
drive, but one in which the engine runs at normal operating temperature and
rpms for some time after the choke has been pushed off.  After a "normal"
drive, the inside of the pipe should be light gray or brown.  If it is dark
gray or black, you've got a problem, usually a mis-adjusted mixture, but
possibly also weak ignition, bad valve(s), etc.

>Also it is now idling idling roughly and sometimes stalls at idle.  It
seems to "pop-pop-pop" like an old 2 cycle Saab, but does not backfire,
when going down hills in gear.  It doesn't burn oil.

If you had a Zenith carburetor, I'd guess that you were suffereing from the
infamous Zenith Warp, which causes the engine to lug down and "chug"
unevenly at idle, sometimes to the point of stalling, whenever the vehicle
sitting level or pointing uphill (the warp is not a problem if the vehicle
is pointing downhill).  But you don't have a Zenith, and I don't know
anything about the care and feeding of Solex carbs.  "Pop-pop-pop" is hard
to diagnose via e-mail.  If it's a spitting-sounding "pop-pop-pop," this
could indicate a burned exhaust valve or two.  A quick-and-dirty way to
check for that is to extend a piece of paper over the end of the exhaust
pipe.  The exhaust will push the paper away.  However, if you have a bad
exhaust valve, the paper will be momentarily sucked onto the end of the
pipe when the cylinder with the bad valve goes through its intake cycle.
Of course, if you have a manifold pressure gauge installed (this and a tach
being the only two instruments worth having in a Series along with the
pressure and temp gauges), it will show you if you've got a bad valve clear
as day.   But it's been my experience that a burned valve does not cause
the engine to backfire against compression, or do anything else out of the
ordinary other than the  spitting sound of the exhaust at idle, and of
course, degraded performance.

Finally, if a couple of spark plug wires are switched round, this could
cause the uneven running you are experiencing.  Depending on how the wires
are switched, the engine may run reasonably well, or it may run horribly.
Also, if the points are mis-adjusted or worn beyond limits, this could
cause uneven firing.  So I'd suggest first making sure that the plugs are
connected to the distributor in the correct order and that the points are
in good shape and gapped properly before going on to more potentially
discouraging things like looking for burned valves.

________________________
C. Marin Faure
  (original owner)
  1973 Land Rover Series III-88
  1991 Range Rover Vogue SE
   Seattle, WA