Well I have a small knock in my motor at about 2500 rpm.and I think its a rod bearing.How hard is it to change the rod bearing in a small block chevy.I’ve been reading a few articles and wanted to know from someone who has done it before.I know basically you have to drop oil pan (which I was planning to do to take oil dipstick peice out anyway) take nut off of crank and they say put peices of hose over the bolt ends so they don’t score the crank. dont know about the installation of the bearing them self and if u have to check lash or not ? Any on-topic help would be gratefully appreciated. kthnx :burnout:
If you are planning on keeping the engine in the car(which it sounds like), then it isn’t that hard. Like you say, get the pan down however you have to. You might have to pull the front pulley or the trans cover depending on what car, what year, etc.
Once you get the pan down, figure out which rod it is. Try pushing it up and down or side to side, perpendicular to the journal of course. Find the one with movement and rotate the crank so its at its lowest point, offcenter so you can push the rod up and swing it to the opposite side where you can see the bearing.
Once you get the cap down, make sure the crank looks ok and the rod hasn’t spun. If it has then its going to need turned. If you think its ok, then pull the bearings out and use some brake cleaner and clean the bearing surfaces on the rod and cap real good and get them dry with a clean “non-fuzzy” cloth. You can’t have any crap in between the bearing and the mounting surface or its going to mess up the clearances. Get that all done, torqued down and thats about it.
what about lash between the bearing and the rod or the bearing and the crank do you have to check that or just put the bearing on and torque to spec :dunno: thanks for the help
im not sure about “lash”, thats not the most correct term for this…
what you could do is plastigage it and see what it is with the new bearing(s)
Its pretty much the same as any motor. Use plastigage to check clearances between the bearing and crank. Hopefully for you its not spun.
Doing this in the car is a job I would rather NOT do.
I dropped the pan in my 76 Camaro and had to remove:
The exhaust system and all the accesories from the front of the engine.Then I had to loosen the engine and transmission mounts so that I could jack the engine and tranny up to make room to drop the oil pan. Once that is all done and out of the way then you are good to go. (I didnt have to remove anything when i did this in my blazer. It had a 4 inch lift and plenty of clearance.)
If you are having rod bearing noise it is for a good reason. How is the oil pressure? And are you sure it is not coming from somewhere else? I’ve had flywheels and torque converters make noises that I thought were rod bearings. Cam bearings can also be very noisy and mistaken for failing rod bearings.
I got lucky when i pulled the pan on my camaro and blazer. I was able to use some very fine krokus cloth and polish the rod journals, I checked the back of the bearings and got the exact same size from the auto parts store, then used plastigage to make sure they were within specs.
Reassembly isn’t too bad, but is generally a pain in the ass and you wish that you would have just pulled the engine. :crying:
By this time oil has dripped in your eye, you’ve dropped a bearing cap or 2 on your forehead and have hopelessly stripped an oil pan bolt. you also can’t remember if you removed the plastigage from the bearings, did the final torque sequence on the rod bolts and have run out of beer twice.
Don’t forget to pack some light grease or vaseline in the in the oil pump, put engine oil in and pre lube the engine before you fire it up the first time.