Rod & Main Bearings, how do you know when they need replacement??
12-16-2001, 10:05 PM
#1
Melting Slicks
Thread Starter
Rod & Main Bearings, how do you know when they need replacement??
While replacing the rear main oil seal on my 72 L48 I grabbed a rod cap and wiggled it and noticed a small amount of play in them. They all seemed to have the same amount. The rear main cap that I removed to do the seal showed signs of wear but the base metal was not showing through. I know the engine has been rebuilt at some time, someone has numbered all the caps etc.. but I don't know how long ago. Is it possible to replace rod bearings with engine in the car? Will the engine knock when play becomes excessive?
12-16-2001, 10:42 PM
#2
Re: Rod & Main Bearings, how do you know when they need replacement?? (KJL)
You should look for scoring marks on the bearing surface. Also, look for discoloration on the surface. I think that indicates oil starvation. The best way to do it is get some Plastigage and use that to determine your clearances. Of course, it all depends on how many miles the motor has on it and whether or not it has been maintained properly. An abused engine showing 50,000 miles may need a rebuild, while a higher mile engine may not.
12-17-2001, 05:33 PM
#3
Burning Brakes
Re: Rod & Main Bearings, how do you know when they need replacement?? (KJL)
Quote: "Is it possible to replace rod bearings with engine in the car? Will the engine knock when play becomes excessive?"
Yes, replacement of rod bearings can be done with engine in the car. I did it. Also replaced the main bearings as well. Had 'standards' and replaced with new standards. Installed new stock oil pump as well, have really good oil pressure now.
Yes, replacement of rod bearings can be done with engine in the car. I did it. Also replaced the main bearings as well. Had 'standards' and replaced with new standards. Installed new stock oil pump as well, have really good oil pressure now.
12-17-2001, 10:06 PM
#4
Melting Slicks
Thread Starter
Re: Rod & Main Bearings, how do you know when they need replacement?? (john's '81 mouse)
To do the main bearings, you must have had to drop the crank!! That must have been a royal PITA!! I unbolted a rod cap but could not pull it off. I got it part way but then gave up. Another battle for another day. Still not sure how one can tell if bearings need replacement? The rear main had some mild score marks on it.
12-18-2001, 05:15 AM
#5
Racer
Member Since: Nov 2001
Location: Lake Hughes CA
Posts: 251
Likes: 0
Received 0 Likes
on
0 Posts
Re: Rod & Main Bearings, how do you know when they need replacement?? (KJL)
There used to be a small tool available to allow you to replace mains without dropping the crank. To remove to old bearing, you would place this "thing" in the crank oil hole and rotate the crank. This "thing had about an 1/8 inch diameter shaft with a large "head" on the end. When you rotated the crank, it pushed the bearing around to where it could be pulled out. To reinstall, reverse the process. I did this a few times, but it was like 25 years ago.....
