[xj40] Knocking noise

XJ40
1

I have a knocking noise from the engine area even while the car is
idling and not in motion. It happens about twice per second on idle
and speeds up a little when the accelerator is depressed. I seem to
be able to feel this if I keep my foot on the brake pedal whilst
stopped. Any ideas on this one please.–
bassbandit
St Austell / Cornwall, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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2

In reply to a message from bassbandit sent Sat 1 May 2004:

What year / model of car?

Be more specific - the engine area is pretty large! Can you isolate
it to a more precise area - even using a mechanics stethoscope (or
a long screwdriver pressed to your ear and t’other end placed on
the suspect area)–
The original message included these comments:

I have a knocking noise from the engine area even while the car is
idling and not in motion. It happens about twice per second on idle
and speeds up a little when the accelerator is depressed. I seem to
be able to feel this if I keep my foot on the brake pedal whilst
stopped. Any ideas on this one please.

–
Bryan N ('91 Sovereign 4.0 L)
Cambridge, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

3

Hey mate, did you ever figure out what the issue was with the knocking? I’ve just purchased an XJ40 and it’s got the exact same issue.

(sorry for bumping a 16 year old topic)

Cheers

4

It might be the return fuel check valve. It makes a tock tock tock sound and is easily fixed.

5

Thanks Graeme, I’ll check that one out.

6

Also known as the helicopter noise :slight_smile:

8

Gentlemen …

As Bryan, our beloved Godfather of all things XJ40, sagely stated … “Be more specific - the engine area is pretty large!”.

Please take Bryan’s advice and use a mechanics stethoscope to track down the noise. If you own an XJ40 and you don’t own a $10 (for a really good one) stethoscope you are relieving yourself into a brisk breeze.

1 Like
9

Unless I’m mistaken the ‘helicopter’ noise is due to.a faulty damper in the fuel feed hose ahead of the fuel pressure regulator, not the non-return valve.