[xj] whine at idle on 90 xjs v12

When I start the engine, all is well (there is a low groaning
sound, but that stops when I rev the engine a bit; probably the oil
needs a little extra pressure to get to some spot). But, here is
the problem: Within a minute after beginning to drive, I get a high-
pitched whine whenever the engine returns to idle–as at those
moments when I am coasting or at a stop sign. The minute I
accelerate, it stops. It makes no difference whether I accelerate
in neutral or in drive. So, the overall effect is that I hear this
whine whenever I slow down or stop. The sound comes from the
engine or transmission (not back under the rear seat or boot
area). If I put it in idle and rev the engine, it stops. But once
I start driving, the pattern begins again–stop & whine & slow down
& whine, and so on. It is particularly irritating when I am in a
close spot between cars or in a parking garage. I have opened the
hood and looked–to no avail. If I put my hand over the air intake
on the driver’s side, and choke the engine a bit, it stops. Overall
the engine seems to run well–slow new york city driving consumes
about 6 mpg (which I have attributed to the demands of the v12
engine) and it very occasionally misses and/or dies when I am
negotiating heavy traffic in warm weather (which I figured was just
from water, gas, carbon build up, etc). The Jag repairman wrongly
thought the sound was from the alternator and, at considerable
expense, replaced it. What is this sound from? I’m thinking a
vacuum leak (but wouldn’t the sound continue on acceleration?) or
something in the transmission. It’s the latter that has me
worried. Do you have to fool with the engine mount on a 90 xjs to
clean out the transmission? Any advice would be welcome!
Lawrence–
ulysses
Jersey City, NJ 07306, United States
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Lawrence:

First, the groaning sound you hear when you first start the V12 is
“normal”. It disappears as the engine begins to warm up, and it is heard
more frequently in cooler weather. It is from one of the vacuum system
valves, and is harmless.
This is not the concern. The high pitched sound you hear at idle: I
would suspect that it comes from the air pump system, but have you
checked the entire vacuum system for leaks?

Your fuel consumption: dreadful; have you serviced the distributor to
make should the weights are moving freely, and is the vacuum advance
unit working properly?
Your XJS has a Marelli ignition system (not the Lucas system) and it
need to be in top condition: the rotor and cap especially and the plug
gaps within specified limits, or problems will arise (the XJ V12 saloons
on this list do not have this concern as they used the Lucas system
right to the end of 1992).

Gregory-----Original Message-----
From: owner-xj@jag-lovers.org [mailto:owner-xj@jag-lovers.org] On Behalf
Of ulysses
Sent: October 3, 2006 8:42 AM
To: xj@jag-lovers.org
Subject: [xj] whine at idle on 90 xjs v12

When I start the engine, all is well (there is a low groaning
sound, but that stops when I rev the engine a bit; probably the oil
needs a little extra pressure to get to some spot). But, here is
the problem: Within a minute after beginning to drive, I get a high-
pitched whine whenever the engine returns to idle–as at those
moments when I am coasting or at a stop sign. The minute I
accelerate, it stops.

===================================================
The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
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In reply to a message from Dr Gregory Andrachuk sent Tue 3 Oct 2006:

I disclaim being an expert on anything and certainly not the V12!
However, whine disapearing on acceleration suggests a vacumn issue.

My Jeep had such a whine. it went away when the catalytic converter
was replaced to pass smnog! I don’t understand why, and will spend
little if any time musing about a problem tht didappeared!

Carl aka Jagcad–
The original message included these comments:

This is not the concern. The high pitched sound you hear at idle: I
would suspect that it comes from the air pump system, but have you
checked the entire vacuum system for leaks?
the problem: Within a minute after beginning to drive, I get a high-
pitched whine whenever the engine returns to idle–as at those
moments when I am coasting or at a stop sign. The minute I
accelerate, it stops.


Carl Hutchins
–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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No need to worry about advance mechanism with Marelli ignition, Gregory
:-). It’s electric. The others items you mentioned, yes, very important.

Doug Dwyer
Longview Washington USA
1995 XJR
1988 XJS V12 CoupeFrom: “Dr Gregory Andrachuk” v12-vdp@shaw.ca

Your fuel consumption: dreadful; have you serviced the distributor to
make should the weights are moving freely, and is the vacuum advance
unit working properly?
Your XJS has a Marelli ignition system (not the Lucas system) and it
need to be in top condition: the rotor and cap especially and the plug
gaps within specified limits, or problems will arise (the XJ V12 saloons
on this list do not have this concern as they used the Lucas system
right to the end of 1992).

===================================================
The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
Archives: http://www.jag-lovers.org/lists/search.html

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In reply to a message from Doug Dwyer sent Wed 4 Oct 2006:

Thank you to all! I am planning to check vacuum lines this
weekend. The Jag repairman (not a Jag dealer) in NYC says it is
not the air pump. He replaced the idler pully, but no cigar. He
detached the various belts, each separately, but no results there
either. I think the mechanic was not very committed to finding the
noise. The car has to be driven, then placed in idle, for the
sound to occur. And it always does. Then a mere rev on the engine
will stop it! He drove the car, but I could tell he also listened
to the radio (on a detestable channel). Not cool. Yes, the mpg is
very bad, but keep in mind that my 8 mile commute to Manhattan
takes me 45 minutes. Coming home is usually even longer. In case
of success on all this, I will report back. Lawrence.–
ulysses
Jersey City, NJ 07306, 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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The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
Archives: http://www.jag-lovers.org/lists/search.html

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