The Stovebolt Site Forums The Shop Area Engine Shop Connecting rod bearings

I was going to install my oil pan when I noticed a thin, half inch long scar on the front inside of the pan. It lines up with the number 1 rod cap. I have found that all my connecting rod bearings are worn out. This explains the knocking sounds I was hearing and the low oil pressure.

What I have is 010 bearings. Do I need to get some Plastigage and measure each rod bearing ? Or just replace them with the 010 bearings ? I have never used a Plastigage.

1960 235 with a 1954 Hydra-Matic

Thanks in advance. Michael

If the bearings are worn out, you really should take the crank and have it checked out by a machinist and see if its still in spec. If it is, you could just order new bearing the same size and put it back together. If it's not, then you will have to get it machined and go the next bearing size up, or more, depending on the condition of the crank. Some one with more experience and knowledge will come along soon and explain it better than I.

I would think that if you had enough play in a rod bearing to have the rod hitting the pan, the rod would break and come through the block pretty quickly. I wonder if you have a dented pan.
What do your rod bearings look like? You would be wise to examine the appearance of the crankshaft and the clearance of the bearings before buying more.

The rattling noise tells there is a problem, unless there is a dented pan as mentioned above, best to use plastiguage on all bearings while you are at it. No use tearing something up.

Ed

Even a totally missing bearing wouldn't let a rod hit the pan, and the noise from a bearing that loose would sound like somebody inside with a sledgehammer trying to beat his way out. Use a carpenter's square or something similar to measure the distance the rod drops below the pan rail, and then compare that dimension to the depth of the pan. I'm pretty sure you're going to find the pan is bent- - - - -possibly by somebody putting a jack in the wrong place when changing a tire, etc.
Jerry

Have some pictures.

1. Front of oil pan the scratch is about 1/2 inch long, no dents in the pan and the pan appears to lay flat on block.


2. No. 1 rod cap was scraping the bottom of the oil pan, there is a shiny mark on the rod cap right side and almost center on the lip


3. No. 1 on the crank has a raised ridge in the center. It going to need machined.
I pulled the No. 2 rod bearing cap and it looks much better.


I did hear thumping noises after the engine & the Hydra-Matic got warmed up. I always thought it was the Hydra-Matic making all the noise.

Will post more as I disassemble the rest of the rod caps and get the crank machined.

Thanks for all the input. Michael...

Can't see the pics- - - -I'm not sure if others can. Unless the crank journals are completely smooth to the point a fingernail can't hang up in a score mark the crank will need to be reground. What you're describing sounds like the crank is junk, or will have to have at least the bad journal welded up and reground. It's usually less expensive to get another crankshaft.

You're into complete teardown and overhaul territory now. The crankshaft is virtually the last thing that's removed after taking the cam, lifters, front timing plate, pistons, connecting rods, etc. out. The metal displaced by the bearing and crank wear will be distributed through all the oil passages, etc. so be sure to do a very detailed cleanup of the block. Have fun!
Jerry

Healingbear , you must utilize the “Share” function on Google to enable the rest of us to see the photos.🛠

If you have to take the motor apart and get the crank redone, keep in mind that these cranks can be machined pretty far and still maintain their integrity. I have a motor I redid for a friend where the rods and mains were machined .060 and that motor has been running for well over a decade now. If the crank is out for machining, have the machine shop drill and tap the front snout for a balancer bolt (small block chevy). Makes installing the balancer way easier in that you can use a regular balancer installer instead of the hammer and block method (which can damage the thrust bearing if not done correctly putting forward pressure on the crank while beating it on). If you have room, you can install a Mr. Gasket balancer bolt for a small block chevy to keep the balancer in place. You might also want to consider obtaining a spare balancer and making a timing cover/seal centering tool out of it. Its easy. Drill and drive out the rivets in the balancer and separate out the components. Take the hub and run a brake hone through, sneak up on it, it until it will just slip onto the crank snout without interference, not too loose in other words. When you are ready to install the timing cover and new seal, just install the screws/bolts sort of loose, leaving the cover loose and slightly movable. Install the new centering tool, center the seal on the crank snout, and then tighten the screws/bolts. Helps keep leaks at the seal from out of alignment snout to a minimum. Kent Moore use to make a tool for this but somewhat hard to come by these days so a little backyard hackerwork to the rescue.

The crankshaft drill/tap/balancer installer/timing cover alignment tool kit I've been renting and/or selling to stovebolters for about 15 years does all of that. It even works on assembled engines.
Jerry

Jerry, do you still sell that tool?

Mike

You've got enough posts now to use the PM function. Drop me a message or email at actionenterprise@yahoo.com

Jerry

Apparently not quite yet, lol. I will shoot you an email.

It normally takes 4 or 5 posts- - - -maybe I'm over my limit on PM's.

That may be the case hold on, let me try again.

Before one does extensive machining, make sure appropriate undersized bearings are available.

Ed

There's still plenty of good-condition crankshafts available. One salvage yard in Albert Lea Minnesota has several on Ebay most of the time. Shipping charges are a little steep, but they even have a few standard-diameter ones listed.
Jerry

I hope the crank be ok to get machined, if not maybe my spare 3701488 crank will be ok. Will have a conversation with the local machine shop Tuesday. They have been in business for almost 100 years.

I am considering doing or having the engine rebuilt. Its been many years since I done and major engine rebuilding.

As Jerry pointed out, there most likely is residual medal fragments in the oil passages having the block dipped should take care of that.

That and make sure to remove the cam bearings before dipping, Bristle brushes for all passages.

Ed

Rod bearings are readily available in .010, .020, .030, .040, .060. I have seen them in the past as much as .080 but I would not myself be inclined to go that far, lol. I am a fan of careful precise machine work. The last crank I did was magnafluxed, cut to .030, indexed and equalized, drilled the snout for threads and balanced and I think I was around 320 or so. The 261 I built two years ago is what I put that crank into, it is a very modified motor (GMC rods, forged pop up pistons, Schneider cam other stuff, lol), and I run it pretty good with no issues so no worries if you have to regrind the crank.

healingbear, you're still missing something. Google wants me to sign in to view your photos. Maybe it's just me!

The connecting rod boring jig I'm in the process of fabricating will allow me to machine Babbited rods for insert bearings, either the increasingly scarce ones that have been around for years, or the more commonly available bearings that fit a Massey-Ferguson tractor with a Perkins Diesel engine. All that needs to be done to the bearing is to drill one hole in it to align with the oil dipper in the rod. The Perkins bearings are about $5.00 apiece and require the crankshaft to be ground .060" undersize. That allows a worn-out 30 under crank to be salvaged by running a std. diameter, inexpensive bearing. The crank doesn't really care what size it is as long as the journal is round and accurate, as there are lots of NASCAR racers running 350 Chevy engines with Honda rod bearings 1/8" smaller than standard and turning 8K+ RPM.
Jerry

I have redone the picture post and viewed in in a different browser after editing the post. I posted pictures back in August, I thought I did it the same way, guess not.



Fixed the pictures #2


1. Front of oil pan the scratch is about 1/2 inch long, no dents in the pan and the pan appears to lay flat on block.


2. No. 1 rod cap was scraping the bottom of the oil pan, there is a shiny mark on the rod cap right side and almost center on the lip



3. No. 1 on the crank has a raised ridge in the center. It going to need machined.

The amount of damage on that crank journal might be more than regrinding will fix. It's uncommon for cranks to be ground more than .030" undersize unless you have a source for those scarce and expensive smaller bearings. The tractor bearings I described require some custom resizing of the connecting rod. They're not a direct-swap situation with regular 235 rod bearings.

I'd definitely suggest doing a little massaging of the center of the oil pan before you reassemble the engine. It looks like there's a much closer relationship between the rods and the pan than I've seen in the past.
Jerry

healingbear, success, the photos are viewable.

Thanks for fixing the photos.

Ed