Rod bearings (1 Viewer)

[srafj40]

Have a knock that I have been chasing.

Dropped the pan and replaced the bearings. Started it up and the knock was gone... (good job smiles all around/drink a beer)

...until it warmed up.

Could I need an oversized set or do you think it is deeper/main bearing, cam, etc...?

Please give me your thoughts Ladies and Gents.

Thanks in advance.

 

[rsbcruiser]

Try the old disconnect the spark plug trick. Move through the plugs with engine running, if the noise quites or goes away on a cylinder then you know what hole it is. It could be your piston slapping the wall or the pin could be bad. Did you take the pistons out when you replaced the bearings? unfortunately, there are lots of other reasons for a knock.

 

[65swb45]

Take a hollow rod or wooden dowel, or something you can use as a poor man's stethescope and try to isolate where the knock is coming from. IF the knock is coming from the FRONT of the engine, don't discount the possibility that it could be coming from the timing gears.

If this thread is a follow up to an earlier one on this issue, you should link to the discussion on it.

 

[srafj40]

If this thread is a follow up to an earlier one on this issue, you should link to the discussion on it.

Talking about these ones:

https://forum.ih8mud.com/showthread.php?t=168809&highlight=rod+bearing

https://forum.ih8mud.com/showthread.php?t=184004&highlight=knock

 

[grant5127]

Could I need an oversized set

Plastigage is "Mans best friend"......

 

[morrison]

Did you mike the crank while you had the rod caps off? FWIW, I may be old school, but I was taught by a lot of older-timers than me that it's pretty much a gamble to think you can shove in new rod bearings and hope the crank is still round. I have tried this twice when I was a dumb teenager and both times the bearings were toast in about 5 miles because the crank really needed grinding. Maybe F's and 2F engines have tougher cranks, but all the old 50's and 60's Chevy and Ford engines we used to tear into always had bad cranks if there was a knock. Course a set of bearings for a 235 six only cost $4.00 in those days so we weren't out much.

Main bearings are different--not as much off-center wear.