(62 Scout 80 4cyl)the knocking noise in my flywheel/clutch area now apears to be coming from the bottom end,specifically the rear of the bottom end.I went through all the usual suspects,clutch adj,loose flywheel ect,ect.the noise starts out early unnoticeable and as the engine warms it gets louder,my new rear main seal also seems to have developed a leak(engine is slightly overfilled with oil so it could be that).heres my question,can I drop the crank out of the motor,have it machined .010 under and replace the main and rod bearings without pulling the motor?(I dont have the equipment or help to pull the engine at the moment) my local napa can get the bearings for me (sealed power) and there is a really good guy here in town that does nothing but cranks,mostly for race applications.if you guys have attempted something like this id like to hear about it,im totally unfamiliar with this engine and the knowledge here is invaluable to me.thanx
4 cyl engine issues
- Thread starter NONYAMT
- Start date
Robert Kenney
Super Moderator
Yes you can pull the crank with the engine still hanging on the mounts but it is not worth the trouble. Still have to pull the front cover and trans, transfer case etc. You can install new bearings however with out much trouble.
Measure the crank and see what your clearances are. Do for both mains and rods.
Stock main journal is 2.7484-2.7494. Stock rod journal is 2.373-2.374. Subtract as needed the under size condition marked on the bearings as you have posted.
If you find a good finish on the crank surfaces and a good size simply roll in new bearings.
Before running again install an oil pressure gauge and see what you get.
Measure the crank and see what your clearances are. Do for both mains and rods.
Stock main journal is 2.7484-2.7494. Stock rod journal is 2.373-2.374. Subtract as needed the under size condition marked on the bearings as you have posted.
If you find a good finish on the crank surfaces and a good size simply roll in new bearings.
Before running again install an oil pressure gauge and see what you get.
Robert Kenney
Super Moderator
Let's rule out rods and mains for sure before we go to long shot theory's. Measure each journal and post your dimensions.. You will need a good 3" micrometer with .0001 graduations. Not very expensive. Iirc you can buy a 1-6 boxed set from local places for just north of $ 150.00. Small investment if you seek to do any meaningful engine work.
Hf has a 1-3" set for $29.00 plenty accurate a you can judge .0005 reliably.
Hf has a 1-3" set for $29.00 plenty accurate a you can judge .0005 reliably.
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
80% of all internal engine noise in the ihc-produced applications is due to valve train problems involving plugged rocker shafts. The rest of the "noise" is related to one or more pistons that have a "collapsed" skirt resulting in extremely loose piston-to-cylinder clearance. And the engine with piston noise will run forever and just be noisy.
I have torn down engines this past year that had huge wear issues on the rods and mains, but those engines did not make any noise at all, they simply produced little useable power. These engines are not chryfordrolets, they do not lubricate the same, and they are not assembled the same. They are unique in many regards.
Simply "looking" at parts such as this gives only a basic idea regarding actual component history. In order to determine the actual condition of all bearing journals, cylinders, pistons, etc., the stuff must be measured and the resulting data compared to the specifications. That means tools must be obtained in order to be able to measure this stuff.
Again, I advise you to take the time to read through every thread in the engine tech sub-forum and you will find many issues where the wrong process was used to determine what was was an engine problem and much money was spent for no return because the actual fault was never corrected.
I have torn down engines this past year that had huge wear issues on the rods and mains, but those engines did not make any noise at all, they simply produced little useable power. These engines are not chryfordrolets, they do not lubricate the same, and they are not assembled the same. They are unique in many regards.
Simply "looking" at parts such as this gives only a basic idea regarding actual component history. In order to determine the actual condition of all bearing journals, cylinders, pistons, etc., the stuff must be measured and the resulting data compared to the specifications. That means tools must be obtained in order to be able to measure this stuff.
Again, I advise you to take the time to read through every thread in the engine tech sub-forum and you will find many issues where the wrong process was used to determine what was was an engine problem and much money was spent for no return because the actual fault was never corrected.
Thanx michael,I know this engine was rebuilt and then sat for 10 years or so without running.on each bearing you can see pitting in a spot,probably where the metal was making contact for all that time.ive got a new set of bearings waiting for installation and I have replaced the lifters and pushrods(removed 90% of the engne clatter).the inside of the engine looks suprisingly good,I have plastiguaged and the mains are 010 under,rods 030 under what cleavite lists as standard.im probably just used to quiet smooth running motors but with this engine sitting for so long im going to feel much better having gone through it.its not going anywhere any time soon,its this coming winters project,just trying to get the drivetrain sound this summer so I can start on the exterior/interior this fall!