Guidelines for Bearing Inspection

[EngineerDoug]

Hello all,

I am working my way through the '68 383, evaluating the health of the motor with an eye toward minimizing expenses. This motor will serve as a very mild powerplant for a while, and I have been busy replacing seals and cleaning up the accumulated layers of grease and grime. The goal is an engine that is well sealed, runs acceptably, and will serve for perhaps another 10K miles. A new engine it is not, but indications are that it has some life left in it. The engine does run, and the vital signs are reasonable.

Now I have it on the stand and have cleaned all the sludge out of the oil pan. I would like to have a look at the bearings to get an idea of their condition.

So I have a few questions before I charge into this. I assume it would be best to pull one main cap at a time, or does it matter? (It goes without saying that I will keep everything in order as it is removed). Note I intend to replace the rear main seal while I am at it. As for rod bearings, should I pull these caps as well? Or pull them only if the mains look questionable? Given this is a stock motor, and has never been disassembled, would I be foolhardy to re-use the main and rod bolts? Note again this engine will probably never see >5000 rpm.

I will surely ask some more questions and/or post photos once I have bearings in hand. Any guidance or words of wisdom are appreciated.

Thanks.

 

[MarPar]

ill be watching this thread...

 

[khryslerkid]

 

[EngineerDoug]

Yup, got the book and read it. I just wanted to see if there was anything beyond that - tips or tricks - that I should know.

I think I'll pull one cap and post fotos. Thanks.

 

[5.7 hemi]

This saying goes for anything and everything in life, when in doubt, change it out!

 

[khryslerkid]

If there was a lot of sludge then there is probably lots of wear in the bearings, rings, cylinders, timing chain ect.

Your right there, I'd do the whole total rebuild.

 

[wagonman]

Did just this a while back on a 70 383 mag. Checked all rods and main thrust,all Ok slapped it back with a new chain and pump gaskets ect. Drove the snot out of it. Never underestimate Your Mother.

 

[69L48Z27]

If you did a compression test and cylinders are consistent and no scoring you would fine there. If you pull caps and see gouging and scoring then you need to do the rebuild and machine work. Or maybe not.

If it ran good and compression/oil pressure is ok then throw it back together and enjoy.

 

[EngineerDoug]

Oh boy do I have a dilemma now. I pulled all the main caps. Several of the bearings show deep scoring. The good news is that the crank journals look very good. There is absolutely nothing that will catch a fingernail, and the surfaces are almost imperceptibly marked - if you look closely. The bearings are clearly crap.

I've set a goal of "no machine work" for this engine. I am replacing the timing chain & oil pump, BTW. Maybe I am living in fantasy land, but indulge me. Given the state of the main bearings, I would think the rod bearings would be in similar shape. So here is my proposed plan:

1) Unbolt the rods and confirm those bearings are also shot.
2) Pull the crank out, because it will make replacing the main bearings easier. I've also got to replace the rear main seal, and getting that out with the crank installed looks like a major headache. Every seal in that engine is hardened after 48 years, and I doubt I could get all of the rear seal out any other way.
3) Install new main & rod bearings, assuming I find no big uglies anywhere on the crank.

So please chime in - I know this is an "on the cheap" job, but as some of you have said, it did run OK and compression was good. Drop the crank?

Thanks guys; I appreciate the guidance.

 

[62 Dart Convertible]

Pull the crank for sure. Main and big-end journals should be measured to check for 1. Wear and to see if it needs re-grinding, and if not, 2. If it has been previously re-ground so you get the correct bearing sizes. Upon re-assembly, use plastigage to check clearances. This is the minimum you should do.

 

[miller]

Even if you only want to spend the minimum amount of money on it...keep this in mind...the motor had sludge, and carbon in it. Loose carbon in a motor is like tossing a handful of sand in it. That's along the same lines that beat up those bearings.

Pull the crank. If it's still 'sized' right, could just take some hand polishing on all the journals. Here's the kicker...each oil galley in the block needs to be 'scrubbed out', to get the crap out of them. If not, trash there could wipe out the new bearings you put in.
Even just replacing gaskets, seals, rings, and bearings will help. But, motor needs to get cleaned, however you decide to go.

 

[EngineerDoug]

Sounds good - after sleeping on it I realized the only way to go is pull the crank, check it, pop for all new bearings, and plastiguage it. I will clean out the oil galleries as well.

Short of hot-tanking the block, what's the best solvent/solution to use for cleaning?

 

[EngineerDoug]

OK I've got all the rod bearings out. These look much different from the main bearings. They show no lines or scoring, and are a uniform grey color/texture.

The good news - the crank throws and journals look very good. I am not an expert, but I am hard pressed to see anything other than a shiny polished surface. The next step is to mike the journals and throws. I'll be happy if all I need to do is replace the bearings.

Soon I will have a look at the cylinders. I can see nothing ominous from the crankcase side. Maybe I'll get lucky and be able to get away with honing and new rings.

 

[miller]

You'll have many decisions to make, how far you want to go. Such as...
Cylinders...a big no-no is a ridge at the top, where the piston rings upper travel on the stroke stops. If there is a ridge...needs to be cut...or the cylinder 'shape' can be bellied out in the middle. Just takes careful measuring, to find out what you have. Very least, if their straight, and still sized okay, run a lapping tool through 'em, just to freshen the surface. Gives the new ring something to seat on.
Oil galleys...the crank main journal galleys go through the crank itself, but also feed to the cam bearings. That would call for pulling the cam, to be able to clean those galleys in the block!
Tappets...IF you pull them, planning to re-use them, they MUST go back into the same location. Of course, pulling the cam, means tappets need to be pulled, too.
Be sure to check your timing chain for slack!

On and on.....

 

[HEMI-ITIS]

Measuring everything is very important.Bore,rods ends,crank endplay,cam movement,,,,,,
If you have a flat tappet and reuse that stick,the lifters MUST go back on the same lobes.
Clean,inspect and measure ring landings,very important!
I also really like the SUPERPERFORMANCE gaskets and a windage tray id a good idea if you enjoy RPMs over 5k.

 

[moper]

Two notes...
1. you cannot visually see, nor will plastigage show, potential problems in the journal surfaces. They should be measured with a micrometer, carefully and properly. Only then can u tell if it's good to run.
2. I make it a point to never, ever run new bearings on a worn journal. I would suggest you at least have the crank turned.

 

[miller]

If, and only if, the crank journals, both mains and rods, 'look' good, lol and measure good, might get away with just polishing 'em. (Big if.) Though, I have done it, can be done by hand.
But, agree the journal surfaces NEED to be worked, what ever they need.

Honestly, sounds like your wanting to do a gasket overhaul on it. That's okay...if the hard parts are up to snuff.

 

[EngineerDoug]

I appreciate all the tips. Honestly I am looking to do a "gasket overhaul" on it, but understand there are many corners it would be foolish to cut. I will take the crank to a machine shop and get their expert opinion on it, because I don't have the experience to evaluate it. I can mike it, but eyeballing any surface imperfections and making the call as to whether it can be polished is out of my wheelhouse.

Here's one discovery that might shock you...I pulled the camshaft and found that at least two of the cam bearings were broken. Not just worn, but chunks on the edge of the bearings were missing. These chunks were maybe the size of a small fingernail. I heard them hit the garage floor "plink" as the cam slid out. How the devil does something like that happen? I had thought this engine was stock and had not been apart, but clearly somebody had been in there and caused this mayhem. As I mentioned a couple weeks ago, this engine was running fairly well on my stand, but boy am I glad I decided to tear it completely apart. New cam bearings are on the way, and this block will get completely cleaned inside and out. And I will probably pop for the Summit K6400 cam kit while I am at it.

If nothing else, working on this 383 is a good learning tool for me. I've done some engine work before, but never this deep into the bowels. Like anything else I know how to do, I've learned it by tinkering, making a mistake or two, and then getting it right. So thanks again for bearing with me (gosh was that a bad pun?).

Anybody seen broken cam bearings before?

 

[moper]

I have what was billed as a running 383 on a stand now. Crank's at the shop, re-ring job in process with me, because it was full of mice, had some bent pushrods from the owner turning it with a socket and valves being stuck. These engines will take a lot, provided a few things are respected. The cam bearings can deteriorate due to age and less frequent oil changes. Replace them and move on.

 

[miller]

So thanks again for bearing with me (gosh was that a bad pun?).

Heck yeah! Hehe. Your a heck of a lot better learning like you are...that's how it's done. Sure, finding bad/busted parts is kinda the norm on these things, usually from used and abused stuff. But, learning what makes 'em tick is the kicker...if your using your own hands.

You can still get away with a basic overhaul, just replace the parts that take normal wear. It's all good!