Engine knocking

[Vernsmith]

Can excessive main bearing clearance cause engine to knock like a rod problem?

[edinmass]

No......you get a crankshaft rumble..........rod knock noise is distinctive. 

[60FlatTop]

Once you drain the oil an oil pan is just an inspection cover.

[TheMoneyPit]

Rod knocking is distinctive, as is crank rumble, pistons slapping etc.  if you know what you are hearing but the first rodeo is a learning experience!

 

Flattop is on the right path, drop the pan and inspect the bottom end with plastigauge and go from that.

 

Either way it isn’t opportunity knocking... for the owner that is. 

[Dandy Dave]

Could also be a wrist pin or cracked and broken piston skirt. Dandy Dave. 

[Frank DuVal]

What engine? Can be a flywheel problem.

[John_Mereness]

Fellow who bought one of my Auburn's had a knock and I suggested repair verses rebuild as it was basically a well done rebuild but older - problem turned out to be timing chain being worn and hitting case.   If you take a tube of say heater hose or washing machine drain hose you can use it like a stethoscope to better pinpoint. 

[60FlatTop]

A repair leaves most parts equally worn. It is a balance you need for a good running engine; equally new or equally worn. Both work fine but no mixing.

 

I have used a 10" extension and a hammer to sound out rod bearings. And a crowbar for thrust clearance. There are a few other checks that are easy once you get in there.

 

Around these parts an old well driller uses his divining rod and kneels over the fender. I'd buy a pan or head gasket. Smells better anyway.

Bernie

Oh, I really do use two brass rods to find underground water lines, but that's different.

 

 

[Vernsmith]

OK guys the pans off, plastigauge mains all with .003 of less and look good. end play is out of spect by about .010 

#3 main has a striped bolt, got it out, will need replaced with something from ace hw.

Flywheel looks good. Rear oil seal missing top half. 

By the way this is a 38 or 37 Lincoln V12. Will start on rods next.

All ideas and help greatly appreciated.  

[intimeold]

#3 main has a striped bolt, got it out, will need replaced with something from ace hw.

 

Whoa, wait a minute.  A stripped bolt on the main cap?

 

1. Was it loose when you got in there? This is a big problem

 

2. Does ace hw, have the correct strength of the fastener?  

 

3. Too late now; but most mechanics would have done a bit more diagnosing, as to the cause of the noise; while the engine could be run. The are ways to diagnose a main bearing noise from a  connecting rod noise ,  or something else. This takes a good trained ear.

 

Anyhow, Good luck on this venture