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Robert Gardner
Frequent User
Username: bobg

Post Number: 52
Registered: 12-2012
Posted on Tuesday, 12 June, 2018 - 04:07 am:   Edit PostDelete PostView Post/Check IP

72Shadow; LRA13020
Started the car for the first time in nine months, engine running quite fast and there is a noticeable knocking noise which I never heard before today,Checked the oil level and it is right between min and max, Is this an acceptable level?
The answer I'm looking for is " Add a quart and see what happens "

Please don't tell me that there could be a myriad of reasons for the knocking noise !!

Thanks,
Bob G.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1970
Registered: 5-2012
Posted on Tuesday, 12 June, 2018 - 04:16 am:   Edit PostDelete PostView Post/Check IP

Bob

There could be a myriad of reasons for the knocking noise. Sorry, but it's true.

Where is the knocking noise coming from, the top or lower part of the engine. Have you ruled out a ticking hydraulic pump. Hydraulic tappets perhaps. Could you give some more information.

Oil level between min and max is perfectly acceptable.
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Mark Aldridge
Grand Master
Username: mark_aldridge

Post Number: 543
Registered: 10-2008
Posted on Tuesday, 12 June, 2018 - 05:06 am:   Edit PostDelete PostView Post/Check IP

Bob, check the bottom pulley is not loose . I have had this problem with my Mulsanne which I sold recently . Might also be worth trying 200cc of TQF in the sump oil.
Mark
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Robert Gardner
Frequent User
Username: bobg

Post Number: 53
Registered: 12-2012
Posted on Tuesday, 12 June, 2018 - 07:16 am:   Edit PostDelete PostView Post/Check IP

TQF ?
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Jim Walters
Prolific User
Username: jim_walters

Post Number: 171
Registered: 1-2014
Posted on Tuesday, 12 June, 2018 - 07:27 am:   Edit PostDelete PostView Post/Check IP

ATF. Automatic Trans Fluid. It has a strong detergent action and will often free up a sticking hydraulic lifter.
If it's a tap tap tap then brake pump or lifter. If it's a thud thud thud then you don't want to know.

SRH8505 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com
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David Gore
Moderator
Username: david_gore

Post Number: 2916
Registered: 4-2003
Posted on Tuesday, 12 June, 2018 - 09:05 am:   Edit PostDelete PostView Post/Check IP

Robert,

As mentioned above, it is most likely a collapsed hydraulic lifter from its recent "holiday", these can take some time to fill with oil and start functioning properly. The ATF addition to the engine oil may but not always help clear the lifter for the future. My experience has been to let the engine idle until it warms up completely before driving the car and this invariably sorts out the recalcitrant lifter.

Otherwise Jim Walters comment above applies......use a long handled screwdriver as a stethoscope to listen to the hydraulic pumps to determine if they are the source of the tapping.
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Vladimir Ivanovich Kirillov
Grand Master
Username: soviet

Post Number: 942
Registered: 2-2013
Posted on Tuesday, 12 June, 2018 - 12:44 pm:   Edit PostDelete PostView Post/Check IP

Well my experience it that the knocking noise could well be the liners squeezing the pistons.

Obviously, the first question would be about the coolant - has it been changed regularly and that in itself given the age of the engine difficult to answer unless there is an accurate record of its maintenance.

One could remove the sparkplugs and feel how easily the engine turns over. If its got a lot of resistance the corrosion in the aluminium engine block is squeezing the liners and the liners in turn are squeezing the pistons. Another way to check is to put each piston at bottom of its travel and check for scouring on the liner bores using a borescope.

The engine should not be run until the source of the knocking is found and rectified unless you want to use the engine as a boat anchor!

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