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Discussion Starter · #1 ·
I am trying to diagnose an engine(?) knocking or "tapping" noise on acceleration, seems worse when cold. I can make the noise accelerating in Neutral but can't hear it under the hood OR under the car. It's easy to hear from inside the car, though. It reminds me of a piston slap noise. Maybe a cracked flexple?
 

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Check the brake pump. Quite typical for the tapping noise to transfer into the car thru a pipe that is incorrectly touching something else. Put your hand on the number 2 brake pump (fore of the distributor( and see if the sound synchronises with what you feel.
 

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Discussion Starter · #3 ·
Knocking or Tapping Noise

Thanks for the tip. I have removed the transmission because of a front pump area leak and a problem with "no retard or holdback" in Manual 2nd gear. I'm going to be checking the flexplate closely and will also be checking the brake pump. The customer/friend has recently replaced a brake pump (I believe). It's located at the left rear side of the engine.
 

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That location suggests the accumulator and/or valve which is donw low on the left hand side. There are 2 brake pumps both located front and back of the engine exactly mid section as they are driven from the camshaft. The front brake pump (pump #1) is just aft of the water thermostat and the rear pump (pump #2) is immediatley fore of the distributor. If you provide your email, I cans end you a photo of locations. On 73-76 Shadows, they had a small design fault whereby the high pressure brake pump line would rub on parts of the firewall causing the pump noise to transfer into the cabin. You can look to see where the line is touching and gently relocate it OR, if the pump is excessively noisy, remove the pump and rebuild it (not as big a job as its sounds but you will need a special tool for its removal whih I can help you with).

Regards,
Rodd Sala

"Rodd Sala has been a Rolls-Royce and Bentley Motor car collector for over 25 years. He has a very good working knowledge of the marque having owned almost every model Rolls-Royce and Bentley from the early 60's thru to current models. Rodd has written articles and inspection reports on this fine marque and has toured the Crewe factory in the UK as part of a special showing prior to the Bentley & Rolls-Royce separation. Rodd was a member of the Rolls-Royce Association in Australasia and was Australia's single largest private collector of Rolls-Royces during the 1990s. Having owned some 400 Rolls-Royce and Bentley cars over the last 25 years – he is well experienced in maintenance, service, care-taking and restoration procedures."
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Discussion Starter · #5 ·
Knocking or Tapping noise

Rodd, Thanks Again! I have a lot on my plate today, but I will be checking that line for the interference problem. You may have nailed tis one as the noise is mainly heard in the cabin near the transmission tunnel. This car is a 1979, so it's a bit newer than the stated problem cars. We will see. My e-mail is [email protected]. Gary Haslip
 
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