Engine knock noise

roddyb34

roddyb34

Senior Member
Its not the old wheres it coming from question ,,,i know it's #3 big end ,,its not to loud at the moment ,,we have had the sump off ,,the bottom end has been rebuilt at some time a long time ago but car wasnt used much but unknown build quality ,,there is stamps on the crank and block indicating 30 and 20 thou ,,the offending rod has no shims left ,if i drop the sump again and the rod cap then get journal measured correctly is it possible to get one recoed rod ,,? and install it ,,it will be head off too i realise,but would like to keep it going a bit longer ,,,
 
you can replace one rod if the crank journal is still smooth and round. It might not be balanced with the others, and by removing the piston you might have an oil burning issue in that cylinder due to the rings not re seating. You could address those issues if you wanted to. But repairs like this on all cars were common back in the day the car was made and driven. In fact, on another Ford product, the Lincoln Model L, the bottoms of the cylinders are chamfered so you can squeeze the rings and install the piston from the bottom without pulling the head when you had to replace a rod. On a Model A, there is not enough clearance down there so the head will have to come off to get the rod out.
 
roddyb34 said:
Its not the old wheres it coming from question ,,,i know it's #3 big end ,,its not to loud at the moment ,,we have had the sump off ,,the bottom end has been rebuilt at some time a long time ago but car wasnt used much but unknown build quality ,,there is stamps on the crank and block indicating 30 and 20 thou ,,the offending rod has no shims left ,if i drop the sump again and the rod cap then get journal measured correctly is it possible to get one recoed rod ,,? and install it ,,it will be head off too i realise,but would like to keep it going a bit longer ,,,
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It all depends on how much luck you have as the rod journal may be worn and the new rod you will be installing will thereby have a reduced life expectancy.

If you find that the rod journal is worn by .002" thousandths then it's time to pull the crank and get it reground. You may find that the crank is now square rather than round. When you say unknown quality build leads me to believe you'll be pulling the crank.
 
thanks for the replies ,,i realise that the crank could be out of shape ,,it's a worry regarding quality of previous work particulary when the rod is out of shims ,it can be false economy tying to keep it alive,,i have a spare engine i should dismantle and check the bottom end ,,i know it needs boring ,but if the mains are ok i could just do rods and pistons ,,,
 
"On a Model A, there is not enough clearance down there so the head will have to come off to get the rod out."

Not completely true, I replaced the rod without removing the piston. Yes the angle is tough and it is hard to drive the wrist pin out but it can be done. I used a small long screw driver and ground most of the plastic handle off except for a small nob on the end. I inserted that end in the wrist pin hole, I got just enough angle on it and drove it through enough to clear the rod, I did not completely remove the piston I just pulled it down enough so the the wrist pin hole cleared the cylinder wall. I'm not much of a mechanic and I did it...it can be done!

Dusty
 
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