Hard engine knocking, help needed!

[Mitch//pa]

its very hard to diagnose a noise over u tube... thats like when a customer calls the shop and holds their cell phone out the window

 

[john charlton]

Hi Marshall ( The quickest 68A in the West !!!)

If all else fails I will reassemble and start the motor with loose head nuts . Right now I have weight on it with the engine hoist and see what the morning brings .

John on sunny Suffolk County England .

 

[Bruce_MO]

I'm with Mr. Kohnke... I'd start with the pan. And just to tell me another indicator of how much hurt there might be, I'd catch the oil in a paint strainer first, before it pours into my nasty & filthy oil drain pain... just so I could see how much metal comes out as soon as I pulled the drain plug. You might find that you can avoid pulling the head (but not likely).

Good luck!

 

[James Rogers]

@ James: I am pretty sure that there is no leak from the exhaust manifold. The knocking sound is metallic hard. And a leak would increase the noise level by load IMO.
Head gasket might be, but I do not find oil the coolant or vice versa.
I will do the simple thumb compression test.

A head gasket failure won't always yield water in oil or oil in water. If it blows in the small portion between 1/2 or 3/4 it will just loose compression and blow back out the carb. The flakes look like babbitt. You may have lost the center main or other.

 

[Big hammer]

@Big Hammer: Did your engine suffer from the same ugly sound as ours does or did you discover other symptoms?

I am just coming back from the car where i took some videos of valve movement by hand cranking and some photos from valves and pistons. I will post them ASAP.

It's very hard to tell/hear the sounds on u-tube, mine sounded like a 16oz hammer hitting the block in the middle of the block if it helps. Sorry for late reply. In my oil pan dipper tray I found pieces of thrust bearing, pulling the motor next

 

[Tinbasher]

It could be carbon build up in the head. You could try some engine cleaner. GM use to have one called "Kleens" and you sprayed it in the carb. and flooded out the engine. let it sit for 30 minutes and start it back up. All kinds of nasty stuff would come out the exhaust. Boiling water was a old trick to. Hard with a Up draft carb though.
I remember my Dad saying that it was common to do a valve job on a "A" every 20,000 miles.

John Poole

 

[Gerald1961]

Now I pulled the pan. This is what I found in the dip area of connecting rod 1 and 2:

 

[Gerald1961]

the rod bearing #1 on the crankshaft has roughly 1,5 mm radial play. Shifting rod and piston up and down within that play makes a metallic dull noise as heard during idle. Rods #2-4 have no radial play.
The main bearings also do not show any play ( neither axial nor radial) induced by hand and look ok.

 

[Gerald1961]

So thank you all for your support! Now I will have to find a good mechanics to to pull the engine and carry out the change of all rods. I cannot do this in my home garage..

Thank You

Gerald

 

[colin1928]

At least you found it before too much damage
Good luck with the rebuild

 

[Beauford]

Fog Lamps

Fog Lamps....couldn't figure out how to load pics on PM....one glass lens moves around. May need a new seal? Slight dent in chrome on one. I am assuming they are fog lamps. I apologize if not.

 

[zzlegend]

Fog Lamps??????????????????????????????????????
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Forgot to start a new thread??????????????????????????????????

 

[Mikeinnj]

So thank you all for your support! Now I will have to find a good mechanics to to pull the engine and carry out the change of all rods. I cannot do this in my home garage..

Thank You

Gerald

You should check all the babbit and clearances on all rods and mains as well as look for damage to the crankshaft and cylinder walls while you have the motor apart. Do it once , do it right.