[xj] screeching or scraping sound when first selecting reverse

XJ
1

brief, and not consistently repeatable. I haven’t yet been outside
the car when trying to localize it. But from inside the car it
sound like it might be coming from the area of the Hitachi starter??

Ideas?–
Ted Macklin/'85 XJ6SIII
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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2

In reply to a message from TMack sent Sat 17 Oct 2009:

Ted:

Yes, I have an idea. I hope it goes into the wrong column.

The thrust face on a bearing shell is worn. Reverse in some manner
presses the flex plate forward snd engages the starter drive pinion
or a protrusion in the bell housing. Sometimes in many specie thse
things in the housing are rather close together.

Perhaps, with both rear wheels in the air, your helper can engage
reverse while you carefully observe the dampener to detect fore and
aft movement. Or apply a stethoscope in the vicinity of the starter.

I hope, this is wrong.

Carl–
The original message included these comments:

brief, and not consistently repeatable. I haven’t yet been outside
the car when trying to localize it. But from inside the car it
sound like it might be coming from the area of the Hitachi starter??
Ideas?

–
Carl Hutchins 1983 Jaguar XJ6 with LT1 and 1994 Jeep Grand
Walnut Creek, California, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

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3

In reply to a message from cadjag sent Sat 17 Oct 2009:

Yeah, Doug had to use a spacer or shim in his Hitachi reduction
gear starter to cure some such noise. I’ll try that first on mine.–
The original message included these comments:

The thrust face on a bearing shell is worn. Reverse in some manner
presses the flex plate forward snd engages the starter drive pinion
or a protrusion in the bell housing. Sometimes in many specie thse
things in the housing are rather close together.

–
Ted Macklin/'85 XJ6SIII
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

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4

In reply to a message from TMack sent Sat 17 Oct 2009:

Ok, I tightened the forward and reverse bands (yes, loose!)
Inserted thin washers 'tween the Hitachi reduction gear starter and
the mounting plate.
Tightened exhaust pipe at CAT; not really that loose.
Checked fan shroud for true centering. OK.
Checked intake side engine mount nut for tightness; damn snug.
With the onset of cold weather, I think it’s time to drop the idle
back to 800RPMs. My hot weather setting of 900RPM + AAV action at
cold start makes for some rather high idle speeds for the first 90
seconds or so…I just don’t need that high RPM when the AC isn’t
running full tilt all the time. (A 1200 RPM cold start idle speed
sends quite a jolt to the mounts when selecting reverse).

As I mentioned, the screech isn’t consistent. And of course, it
wouldn’t sound off for me after all that work. !!! Sheesh!–
The original message included these comments:

Yeah, Doug had to use a spacer or shim in his Hitachi reduction
gear starter to cure some such noise. I’ll try that first on mine.

–
Ted Macklin/'85 XJ6SIII
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

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5

TMack wrote:

In reply to a message from TMack sent Sat 17 Oct 2009:

With the onset of cold weather, I think it’s time to drop the idle
back to 800RPMs. My hot weather setting of 900RPM + AAV action at
cold start makes for some rather high idle speeds for the first 90
seconds or so…I just don’t need that high RPM when the AC isn’t
running full tilt all the time. (A 1200 RPM cold start idle speed
sends quite a jolt to the mounts when selecting reverse).

It’s just taking up slack, Ted…:slight_smile:

The fast cold idle is a requirement for the engine to start and idle
properly when cold. If indeed it idles properly at 800 hot there is no
specific need for a higher idle than that. And if it cannot sustain hot
idle with AC is on in summer you will have the same problem in winter…

…because the main AC load on the engine is the compressor. Which will
engage unless tripped by the Ranco thermostat when the evaporator temp
drops below +2C. Which will of course happen when ambient air temps drop
below something - at which stage the dehumidifying effect of the AC
system is not required as cold air is dry anyway…

But for sure; unnecessary high idle is definitely not a ‘good thing’ -
for the reaosn you mention…

Frank
xj6 85 Sov Europe (UK/NZ)===================================================
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6

In reply to a message from Frank Andersen sent Mon 19 Oct 2009:

Fast start from cold idle occurs for the reasons you mention, but
additionally, on the Federal XK engine (stock)the first 90 seconds
is also about lighting off the CAT. Raised idle is a contributing
factor, but so is the air being injected into the exhaust stream by
the air pump. If all systems are working properly, the startup idle
will rise quite quickly to 1100 or 1200 RPMs and taper off at 90
seconds. I remember Alex obsessing over the surface contact area of
the AAV (flatening the surface and using heat sink grease etc)
against the intake manifold. Which I suppose was an effort to bring
that fast idle down quicker?–
The original message included these comments:

The fast cold idle is a requirement for the engine to start and idle
properly when cold. If indeed it idles properly at 800 hot there is no

–
Ted Macklin/'85 XJ6SIII
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

===================================================
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7

TMack wrote:

In reply to a message from Frank Andersen sent Mon 19 Oct 2009:

Fast start from cold idle occurs for the reasons you mention, but
additionally, on the Federal XK engine (stock)the first 90 seconds
is also about lighting off the CAT. Raised idle is a contributing
factor, but so is the air being injected into the exhaust stream by
the air pump. If all systems are working properly, the startup idle
will rise quite quickly to 1100 or 1200 RPMs and taper off at 90
seconds. I remember Alex obsessing over the surface contact area of
the AAV (flatening the surface and using heat sink grease etc)
against the intake manifold. Which I suppose was an effort to bring
that fast idle down quicker?

The AAV is bolted to the water rail, but the idea is the sanme, Ted. And
whether or not methods of improving heat transfer is more than
marginallly effective; doing it will do absolutely no harm…:slight_smile:

The AAV is also electrically heated for quicker shut-off - but an
important function of heat transfer is the gradual re-opening of the
AAV as the engine cools down. This to ensure that the engine has the
right idle air enhance start, idle, and react ‘correctly’ even starting
at intermediate temperatures…

Compared to an ordinary carbed choke function; the AAV act as a fast
idle cam - while the ECU independantly provides extra fuel according to
engine temps. As such; the AAV probably maintains high cold idle for
longer than strictly required - carb experience shows that the choke can
be relaxed fairly quickly once the engine is running, as we all know…

Point is that the quickest way to heat up the engine is to drive off
immediately - and with pedal input the AAV functions is redundant,
overridden by the greater amount of air provided to the engine via the
throttle. Jaguar likely wanted to make absolutely sure that the engine
wouldn’t stall at the first traffic stop before the engine is warm
enough to survive on hot idle settings alone…:slight_smile:

Frank
xj6 85 Sov Europe (UKNZ)>The original message included these comments:

The fast cold idle is a requirement for the engine to start and idle
properly when cold. If indeed it idles properly at 800 hot there is no

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