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Can't find source of engine tapping sound
Just popping in
Joined:
2018/4/11 18:27
From selkirk ny
Posts: 2
Hello all,

I have had no luck getting rid of a tapping noise after getting the car out last week, It was there last year but was starting to go away after a valve adjustment and some driving. Here is the info I have gathered to help with diagnosis.

Car is 1940 110

Engine rebuilt about 5 k and 5 years ago.

Valves have been adjusted as they were all tight( double checked three times and all were done with engine running and after waiting about 20 min to ensure complete block heat up)

Noise occurs when engine is not thoroughly warm. After about 10 min of driving it is completely gone.

It is in time with the valve train and I confirmed this by comparing to my timing light and by comparing to other tappets with a stethoscope.

I have pulled each plug wire and there is no major change, cyl number 6 seems to affect it the most, but it also affects the rpm the most so slows the tapping down the most. It is not drastic at all and the noise is the same. Seems that the noise is not in the pistons or lower end to me.

The car runs great, starts great, and drives great. I have tried lugging it on hills etc to try to find a rod knock with no issues.

I have been running marvel in the fuel and have driven the car 150 miles so far this year at all speeds and for some longer trips to avoid short drive.

I am curious the combination of driving with tight valves and starting and let idle during the winter a couple times could be causing a valve to stick a bit and slam down. sounds like one valve is the issue.

Again, the tapping is only at idle and can be brought on by a blip of throttle on the deceleration. IT goes away when accelerating and only comes back at idle and is gone completely after a short drive. IT also gets quiet during warm up and comes and goes at times, say once I have driven the car and stopped, then started 30 minutes later.

I am a decent mechanic but have never had anything like this occur. I am starting to question pulling the head and oil pan to check valves and lower end, but perhaps should pull the manifold and spray some penetrating oil down the guides first.

Thanks in advance,

Brian

Posted on: 2018/5/7 8:44
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Re: Can't find source of engine tapping sound
Forum Ambassador
Joined:
2007/5/20 1:34
From Bowral, Southern Highlands of NSW, Australia
Posts: 10178
G'day Brian(itdmachinist),
to PackardInfo, and I invite you to include your '40 110 Convertible Coupe in the Packard Owner's Registry.

Posted on: 2018/5/7 18:01
_________________
Mal
/o[]o\
====


"Out of chaos comes order" - Nietzsche.

'38 Eight Sedan 38's are great! (Sold July 2009)
'41 120 Club Coupe 41's the One! (Sold October 2017)
'48 2222 "Almost" Rolling Limo Chassis and Engine (Sold Sept 2019)
'50 Eight Touring Sedan

Project Blogs:
'41 120 Club Coupe - Locked
Wade's Workshop - Locked
'50 Eight Touring Sedan

What's this? >>>>>> FAQ - Add your Packard to the Owners Registry
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Re: Can't find source of engine tapping sound
Home away from home
Joined:
2008/3/21 18:20
Posts: 2085
Piston slap, or a slightly loose wrist pin. Any sort of stickiness in the valves will cause a lousy idle or at higher speeds a significant loss of power.

Posted on: 2018/5/7 18:31
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Re: Can't find source of engine tapping sound
Home away from home
Joined:
2008/3/4 2:53
From Magnolia, TX
Posts: 450
Look for an exhaust manifold leak/bad gasket. Good luck.

Posted on: 2018/5/7 19:39
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Re: Can't find source of engine tapping sound
Home away from home
Joined:
2009/9/14 15:46
From Salt Lake City, UT
Posts: 355
Fuel Pump ?

Posted on: 2018/5/8 10:15
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Re: Can't find source of engine tapping sound
Just popping in
Joined:
2018/4/11 18:27
From selkirk ny
Posts: 2
It is the wrist pin bushing. Felt it pivot.

Also found a spot under cyl 6 that appears to be grey sludge from bearing material. I am very lucky that there is no damage to the crank. I gotta check the rear main still as If junk came in with the oil it had to hit there first.

Guess I will pull the head and replace the wrist pin bushing and the rod bearing.

Disappointing as this motor has low miles. But I guess these things happen. Luckily the rest of the rods feel fine.

Posted on: 2018/5/9 14:39
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Re: Can't find source of engine tapping sound
Forum Ambassador
Joined:
2007/5/20 1:34
From Bowral, Southern Highlands of NSW, Australia
Posts: 10178

Posted on: 2018/5/9 22:12
_________________
Mal
/o[]o\
====


"Out of chaos comes order" - Nietzsche.

'38 Eight Sedan 38's are great! (Sold July 2009)
'41 120 Club Coupe 41's the One! (Sold October 2017)
'48 2222 "Almost" Rolling Limo Chassis and Engine (Sold Sept 2019)
'50 Eight Touring Sedan

Project Blogs:
'41 120 Club Coupe - Locked
Wade's Workshop - Locked
'50 Eight Touring Sedan

What's this? >>>>>> FAQ - Add your Packard to the Owners Registry
Transfer the post to other applications Transfer







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