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MG TD TF 1500 - noisy td engine

My 53 TD developed a tapping noise after winter storage. Tappet clearances 0.012,compression tests 130,
plug gaps 0.025, new silicone gasket on cover, oil level clean and full. I thought the Bell aluminum cover might be the cause as I noticed half moon marks on inside of cover on cylinder one and four. They were not new. I filed the area to remove the marks. Pulled the plug wires for each cylinder and noise disappears when plug wire removed from cylinder one. Any suggestions? TD26621

MJ Thompson

Noise disappearing when pulling the spark plug wire suggests a possible wrist pin failure. If it lets go it usually causes fatal engine block damage. I believe I would remove the number one spark plug and rotate the engine until the piston is near the center of the bore. Either with a good small boroscope or a long thing solid object placed on top of the piston I would try and slowly rotate the engine in the opposite direction that it normally spins and see if if there is immediate movement of the piston or just the slightest delay in movement which would indicate slack in the wrist pin to rod. A better method would be the removal of the sump and investigate. Cranks have been known to break and usually on the number one journal area and yet continue to run so that to could be a possible source.

Just some things I would check. I worked on a car once that had that valve cover and it had the same issue as you found. It was pretty clear that they were made to fit the earlier short rocker shaft and not the later longer ones.
L E D LaVerne

It just might be a loose end of a push rod. Mine are hollow with a solid end I spot welded in place.
Peter Dahlquist

In addition to the wrist pin and loose push rod, sounds like that can also come from a badly worn cam lobe / lifter, rod bearings, bad rocker bushing, sticky valve, or even a rocker that you thought was adjusted but is worn in the middle making settings looser than you think. It's hard to diagnose without hearing it!
Steve Simmons

Start with a stethoscope, soda straw or piece or tubing and see if you can find the location of the noise. Under the valve cover? In the head? Down by the tappet cover near cylinder 1? Someplace else? This may at least tell you where it's not and where to start looking.

Jud
J K Chapin

Not to frighten you, Put a spanner on the starter dog nut,turn the crank back and forth slightly. Listen and feel for movement. A crank letting go at speed is not something I want to experience again.
I have also had a piston crown come off at the top oil ring groove which tapped just before it Went,No damage as it is above the Gudgeon pin.

Autocorrect decided Gudgeon was Gideon and dognut was doughnut!!!!!
Ray TF 2884
Ray Lee

The spark plug wire trick is usually a wrist pin. A few of the items in Steve’s list would not disappear when you pulled the spark plug wire.

Regards, Tom
tm peterson

This thread was discussed between 12/06/2025 and 15/06/2025

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