Play in rod bearings on 3 and 4

We have a 51 Farmall M that has enough play around the rod journals on 3 and 4 that I can move the rod ends enough to hear it "click." I have the standard sized rod bearings in place and we have torqued the end bolts according to specs.
Any ideas what is wrong/how to fix? Oversized bearings?

did you check the bearing journals on the crank before buying bearings? sounds like the crank needs re-ground to make them all to spec.

Are you sure you have a std crank journal,maybe it was turned down at one time.The simplest way to figure it out would be to use Plastigauge to check the clearance and then get the proper undersized bearing.There are undersized bearings in .001 increments up to .003 I believe if it is just a worn journal. Good luck Matt G.

If the looseness is up and down (not along the journal which is OK) The journal needs to be measured and inserts used to fit the journal. Measurement must be using a micrometer, not a caliper. 6 places at angles and along the journal are to be measured. .0015 difference is Ok. Using shims under the standard bearing is also OK. Jim

To fix the problem right your crankshaft needs to be pulled and have your local auto machine shop measure all the journals for wear. They won't grind it undersize unless it needs it. Also have them furnish the bearings. Hal

What El Toro says. If you are not used to using a micrometer your measurements may not be correct. If you want it fixed right take it to a machine shop and don't guess on the bearing size.

did you get the caps back in the right places?
k

so , what are you doing? sounds like you are replacing brgs. need more info. you have standard rod brgs In place .? but... is the
crank standard? if the crank has been turned and you put in standard brgs. you are in trouble. that will give you clearance. from your description nobody can give an answer on the problem. we can not see or touch your engine. which way are you moving the rods? up and down or sideways?if you took out worn brgs. and put in new ones how can you get it to click. did you plastiguage the new brgs. you need to know your clearance on brgs. before you button up the engine. the crank may be egged but you still will not get enough clearance to make it click , that"s for micrometer readings. have you checked the old brgs. for a stamp like .010 or .020 for example. this is what the crank could been turned down to. need more info on this. and the only place shims were used was on the wk40"s inbetween the rod caps. that is a useless idea. i just get the rods resized to the correct measurement on those engines. that is why so many of those engines did not last, as the rods got set too tight. took out shims when not needed. no clearance , no lube.

Just a thought. The later M's use a bigger journal crank and the same rods as an earlier m. To do this they just used a thinner bearing in the later model engines. Not likely but possible someone put the wrong bearings in the box. Larry

You might also check the numbers on the back of the bearings that you removed to see if they were all the same

Not a flame! It is not a useless idea to shim bearings to fit. I was taught by master mechanics at technical school that it is reasonable. A brass .0005, or .001 shim material can be used between the shell and the rod (or main cap), to adjust the clearance to account for wear. It is not commonly done often, but it has its place on engines that need to be in service and or can't be taken down to refinish the crank, or on engines that have no available correct bearings. Jim with a positive attitude

yes jim, I know exactly what you are referring to. but where shims are used correctly is between the rod and cap halves. then as wear indicates shims are removed. I have also seen brgs with shims inbetween the brg and cap. but this is not actually the correct way to go about correcting clearance. this is even interrupting the brg. crush as it has to fit snuggly to the cap and for heat transfer also. about the same thing as using silicone or glue on a loose sleeve. it will not transfer the heat properly. you don"t want the brg. moving around in the cap. as you say it is kind of the last resort fixes. to fix the problem the rods need to be resized to original spec"s. it is not that expensive of a job either.then the brg fits properly instead of trying to match the egg shape of the rod. rod checking and resizing is often overlooked.
in this case we have so little info here and the guy is not offering to help with more info.
my comment about useless idea on wk40"s is that the shims have caused more grief than benefit. they were never adjusted correctly and resulted in more engine failure. trying to explain shims to some guys they are lost and don"t understand the purpose of them. shims are there to be taken out as parts wear not added to worn parts. don"t mean to be sounding negative but I have made things work also in a bind and do know when things will and will not work.
we still don't know if he is talking brg. clearance or rod side clearance. I have a feeling it is side clearance though.

Just to add a little more to the discussion of shims. Perfect Circle offered and pushed pretty hard the use of a tapered shim between bearing insert and rod cap back in the 60's. Their reasoning was a undersize bearing not being available to compensate for some small amount of wear on crank journals. I never used them though.

I think you can still get tapered shims.

http://deckwartaperedshims.com/main-bearing-shim-installation.php

I use them my junk for over 40 years with out problems. For me they are a bit time consuming
to fit. I have never used deckwar shims as I still have new old stock from back when.