Engine Bearing Replacement
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Senior User
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Engine Bearing Replacement
Has anyone been successful in replacing crankcase and rod bearings while the motor is in truck? I've got a 223,6cyl that starting to get noisy like a rod bearing going. I may need to just have a total overhaul but it has run quite well. Any suggestions or advice? Thanks
Fleet Owner
Joined: Jul 2004
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From: NM
What's your oil pressure, measured with a good mechanical gauge? I had a '53 w/223 that nuked out, I didn't get to it soon enough and it spun a rod bearing. It would carry 50 psi at cruise, but go down when I accelerated and go up when I coasted. I always figured it was due to a sloppy thrust bearing (main) bleeding pressure. It's pretty easy to do bearings with the engine in, but I would do the pump at the same time.
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Oil pressure hangs around 50psi on steady drive and sound is like a deep lower end dieseling noise where crank is. I don't think I'd worry about removal/installation of lower portion of bearings so much as I would the top section. Is there a special tool for that, especially around crank?
Fleet Owner
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From: NM
You can use a cotter pin stuck in the oil hole, spin the crank and it shoves the upper half right out. But your description sounds like rods. It would be pretty easy to pull the pan and do some checking...
Hotshot
Joined: Oct 2004
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From: Durham NC
Once a rod bearing starts making noise it's already beating the crankshaft journal out of round and sending nasties throughout the engine. IMHO bite the bullet and pull the engine for a full rebuild. I've never seen anyone sucessfully have an engine live long just replacing the bearings. Even if you do decide to try it, it's still easier to pull the engine first and turn it upside down.
Fleet Owner
Joined: Jul 2004
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From: NM
If it's the rods, I tend to agree, although you probably have a couple hundred miles before journal damage. The rods themselves will get out-of-round quickly. But mains are a good bet to replace if caught early. When they start getting loose, oil pressure to the rods drops quickly and the rods start making noise.
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Hotshot
Joined: Oct 2004
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From: Durham NC
I spun a rod bearing in an 80s 6 cld Chevy van 2000 miles from home. Fortunately I had a friend who lived nearby that had tools and a driveway to work in. I found an old guy that could turn the crank in the block, he even came out and did it in the driveway on a Sunday AM. His equipment was antique, the power cord was broken in about a dozen places, but he did a fine job. I had to pull the head and remove the piston and rod and have a new rod pressed on. Used a hose clamp for a ring compressor to reinstall. Put in one undersized bearing, buttoned it up and drove it for three more years before selling it. The buyer drove it for at least two more years before I lost track of it. I never did figure out why that one bearing went bad.
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Elder User
Joined: Dec 2003
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From: New Mexico
About the only thing that can be done while the crank is still in place is changing out the rear main rope seal. Changing rod bearings is an iffy proposition and saves only time when it should be done properly.
Changing out the rope seal with a "sneaky pete' is only for the truly gifted. I am not one of those. I hear about it being done only urban legend.
Changing out the rope seal with a "sneaky pete' is only for the truly gifted. I am not one of those. I hear about it being done only urban legend.
Posting Guru
Joined: Dec 2000
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From: San Diego CA
Been there done it all over and over. Like has been said its a bandaid. It will buy some time and is only moderately challenging. Scale of 1-10 it's a 6 for a first timer 4 after that. If you decide to go for it the most important thing is to keep it all clean and use some plastigauge to make sure the crank is OK. Then once it all back together start shopping for a replacement or gathering parts for a complete rebuild. Remember rolling in a set of bearings is like asprin for a brain tumor. Your just treating a symptom.
Postmaster
Joined: Jun 2004
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From: Riverside, So Cal
I am confused here. In the limited amount of time I spent building race motors, the differential clearance between main and rod bearings was critical to proper oiling. We always shot for .0005-.0015 difference with the mains being tighter. The oil flows from the tighter main to the looser rod. Replacing a rod bearing presumably will make it a tighter clearance. If the main bearings are worn, the result might reverse that required differential, and starve the rod, spinning/burning the new rod bearing quickly.
Replacing only the rod bearing(s) seems a recipe for disaster to me. I would replace mains as well and plasti-gage everything to ensure the differential clearance. I don't know how that could be done without a rebuild.
If you plasti-gage the mains, then can set the rods looser, you could be fine.
Replacing only the rod bearing(s) seems a recipe for disaster to me. I would replace mains as well and plasti-gage everything to ensure the differential clearance. I don't know how that could be done without a rebuild.
If you plasti-gage the mains, then can set the rods looser, you could be fine.
Posting Guru
Joined: Dec 2000
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From: San Diego CA
Amen Randy I would never stand close to a running engine that had rods replaced and not mains. Thats like using just the sticky part of the bandaid and peeling of the puffy part that stops the bleeding. If plastigauge shows out of tolerence replace or rebuild it. Otherwise it's a grenade with the pin pulled.
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Well, I'm considering what you guys are saying and starting to hunt for a rebuild kit for the 223. What I'm initially wondering is how or by what method you get or manufacture a engine cradle for the old straight six? I've only seen cradles for V8's. I've got a very good cherry picker and wonder if I could take it to an upright engine stand that rotates the motor with help from a friend. Has anyone any ideas or advice? Again thanks
Elder User
Joined: May 2004
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From: saxton pa.
Just some thoughts from an old mechanic , are you sure that you have bearing noise. A loose flywheel or bad harmonic balencer can produce a bearing like noise. If it is loose bearings if you can hear them its allready too late! Sometimes you get lucky and can sneak a set of inserts in-- But the chances are slim that the job will be a permanent repair. There is always the possibility of worn wrist pins or a broken or cracked piston skirt. This still means a overhaul you know what they say--Pay me now-or-PAY! me Later. A cheap fix generaly costs 3-times as much!!
Have A Good Holiday--Hotwrench
Have A Good Holiday--Hotwrench
Hotshot
Joined: Oct 2004
Posts: 15,882
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From: Durham NC
Use an engine stand. They are inexpensive and really handy for overhauling an engine.
Take the front sheet metal and radiator off, just a few bolts, pull the engine and tranny as a unit then remove tranny and flywheel once out of the truck. I'd check the price of a rebuilt short block from someone like Jasper, likely to be cheaper in the long run, all tollerences are correct, and comes with a warantee. Just have the head boiled out, the valves checked and ground, new oil seals installed and bolt it back together.
Take the front sheet metal and radiator off, just a few bolts, pull the engine and tranny as a unit then remove tranny and flywheel once out of the truck. I'd check the price of a rebuilt short block from someone like Jasper, likely to be cheaper in the long run, all tollerences are correct, and comes with a warantee. Just have the head boiled out, the valves checked and ground, new oil seals installed and bolt it back together.