SpitListers,
Just a caution on the oil pressure switches;
A very common failure is for the switch to start
leaking oil, around the plastic housing. It starts out
slowly, but can increase without warning, and empty a
full sump within a very few minutes while cruising.
The light however, will not, come on while the oil is
leaking. It only comes on after the last of the oil
has bled out, and the pump starts sucking air.
This is usually accompanied by the loud knocking sound
of the piston crowns hitting the head, after the
connecting rod bearings have melted, spun, and trashed
the crankshaft due to lack of oil.
(A light show AND a concert, goody!)
Over the years, I have never saved a motor because the
oil pressure light came on, but I have lost three of
them due to oil pressure switch failures.
I install oil pressure guages nowadays. Cheaper, more
reliable (in my experience), and much more useful.
Carter Shore
--- Chip Kigar <ckigar@sound.net> wrote:
>
> Thanks for the reply... but I think the listserver
> is messed up a bit.. look
> at the date on the message.
> I ender up replacing the oil pressure switch with an
> earlier model with two
> wires.. the Turn signal, as I recall, was fixed by
> running a separate ground
> wire... and the ig switch connection I did figure
> out eventually.. did you
> know that if the light DOESN"T come on at all when
> the key is turn.. the
> generator is bad...!
> Visit my DYI circle cutting jig page at:
> http://www.sound.net/~ckigar/circle.htm
>
> -----Original Message-----
> From: Richard B Gosling
> <Gosling_Richard_B@perkins.com>
> To: ckigar <ckigar@sound.net>; spitfires
> <spitfires@autox.team.net>
> Date: Wednesday, December 20, 2000 7:45 AM
> Subject: Re: Electrical puzzles '80 spit
>
>
> >Chip,
> >
> >Ooh, you have got a lot of fun with that car! I
> hate electrical problems,
> and
> > at least my car has almost all original wiring,
> apart from a couple of
> minor
> > mods I made (cigar lighter wire used as live
> source for radio and clock,
> > extension to light switch wiring to enable switch
> relocation, so clock
> could
> > go where light switch was). Wiring circuits
> should be reasonably logical,
> and
> > you should be able to fix anything with a wiring
> diagram an patience, so
> any
> > 'bodges' introduced by the PO are almost bound to
> be bad repairs to fix a
> > fundamantal problem that, in all likelihood, still
> remains as no-one has
> ever
> > tried to fix it properly.
> >
> >From the start -
> >
> >Your lift indicator flashing while the dashlight
> stays on is very bizarre.
> One
> > relay controls all the indicators - there should
> be a live to the relay,
> then
> > the other side of the relay goes to the switch,
> which will connect to
> either
> > the left or right lights, plus the dash light
> (this is from memory, I
> don't
> > have the diagram in front of me, so I MIGHT be
> wrong - check the diagram).
> > BTW, if you have the original drivers handbook
> from the car, the wiring
> > diagram in there is easier to follow than the one
> in the Haynes Manual.
> In
> > any case, the supply to the switch is already
> on/off, so how a permanent
> live
> > can reach the lamp I have no idea - you will just
> have to take the lamp
> and
> > follow the wire lighting it, and see where it
> goes.
> >
> >The left indicator not working when the headlights
> are on may be easier to
> > solve. My guess is that the indicator is not
> properly earthed, and
> somehow is
> > earthing via the headlights (maybe through the
> side-lights and/or brake
> > lights). Thus, when the lights are on, the earth
> route is suddenly live,
> so
> > there is nowhere for the electricity to go. Check
> the continuity from the
> > front and rear bulbs to earth, and clean up the
> connections. You could
> > install an extra earth wire connecting the lamp
> cluster casing to the car
> body
> > just to be sure.
> >
> >Earthing problems can cause all sorts of problems
> that are hard to track
> down.
> > Often the symptom bears very little connection to
> the cause (e.g. poor
> > indicators caused by inadequatley earthed brake
> lights). You just have to
> > check and clean all the connections. A useful
> method is to go round
> checking
> > everything vaguely related to the circuit you are
> testing with a voltmeter
> (or
> > one of those screwdriver-looking things with a
> light in the handle that
> just
> > tell you if something is live), you will often
> bump into a wire that is
> live
> > when you would not expect it to be, or vice versa.
> >
> >How the ignition light is connected should be clear
> from the wiring
> diagram.
> > Off the top of my head, it should go between the
> live terminal of the
> ignition
> > coil (or anything directly connected to that,
> including the ignition
> switch
> > terminal, which would be easier), and the live
> terminal of the alternator.
> > Thus, if the alternator is not generating
> anything, you have battery
> voltage
> > one side, 0V on the other, bulb lights. When the
> alternator is charging
> you
> > have full voltage both sides of the lamp, so no
> voltage drop across the
> bulb,
> > so bulb stays off.
> >
> >I cannot see what the oil pressure warning light
> would have to do with the
> > anti-run-on valve, or why they should be connected
> in any way. I cannot
> check
> > right now on a wiring diagram, but I would expect
> that a live would feed
> to
> > the bulb, which would then be connected to the
> switch. With no oil
> pressure,
> > the switch would close the connection to earth
> (via cylinder block), bulb
> > would light, with oil pressure the switch opens
> and the bulb does not
> light.
> > I repeat, this would be my expectation, without
> ever having got involved
> with
> > this circuit or looked at the diagram myself!
> >
> >Are you saying that your switch has a total of 3
> connectors on it? Aah,
> I've
> > had a thought about the anti-run-on valve - this
> may be an automatic
> cut-off
> > device to protect you from your own incompetance -
> if the oil pressure
> drops,
> > the anti-run-on valve would be activated, and that
> would kill the engine
> > before any damage is done. The anti-run-on valve
> would probably just be a
> > valve in the inlet manifold which would open to
> allow extra air in, to
> prevent
> > the car running by weakening the mixture. This
> would normally operate
> when
> > the engine is switched off to prevent that
> diesel-sounding rattley running
> > that can continue for a few seconds after the
> ignition is off,
> particularly
> > in a hot engine, or one with a lot of carbon
> build-up in the head. If you
> > don't have a valve, don't connect the connector,
> everthing else will still
> run
> > fine.
> >
> >As you might have gathered I am not a total expert
> in the field, but no-one
> > else has replied yet, so I thought you might
> appreciate the benefit of my
> > limited experience!
> >
>
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