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 Post subject: Main and rod bearings
PostPosted: February 8, 2017, 12:38 pm 
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So I bought a used motor. The story goes; the engine was rebuilt and driven for about a week. Then when changing the oil, shavings were noticed in the oil. The guy got scared and let the car sit. Life happened and never got back to it.

I spoke to the guy who helped rebuild the motor. They torqued all nuts to 50ft lb. Only to find out later that they should have been torqued to 60ft. pounds for the Main Bearings & 34ft Pounds for the Rod Bearing.

I purchase the motor. And I have the oil pan off, but have not yet pulled the bearing caps off. Since my expertise is with rotary, I'm not 100% sure on how to tell if the bearings are in fact bad or if the shavings in the oil were normal break in shavings. Since I was not there to see the shavings, I have no reference either.

What should I look for while inspecting?

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PostPosted: February 8, 2017, 1:57 pm 
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Look in the oil pan, there should be enough oil left that you can see something.

I would not thing those torque settings would be enough to cause that. How hard was the engine run before the shavings were noticed?

Graham


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PostPosted: February 8, 2017, 3:11 pm 
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Pull the bearing caps off if there is concern...no choice really. You are already there anyway.

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PostPosted: February 8, 2017, 3:57 pm 
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I think it will be fairly clear, once you pull the caps off & remove the bearings. There is simply no way to tell otherwise. I agree, that small disparity in torque on the bolts wouldn't likely have caused any damage over such a short time. If, however, the pan wasn't scrupulously cleaned, and the oil (or at least, the filter) changed at least twice during that time, particles & filings from the pre-rebuild time could have caused bearing damage.

I'd strongly suggest posting nice, clear pics of both the bearing surfaces & crank. There are LOTS of extremely knowledgeable folks here who will be able to tell at a glance if it's all good or not, and how to diagnose further if required. For example, one of the best tools in existence for checking for crank surface imperfections is right at the end of your fingers - if you drag your fingernail across the bearing surface & it feels like a vinyl record, you have problems. If it feels smooth as glass, your crank is likely fine. The bearings are softer than the crank, by design, and any wear on them should be fairly obvious.

If worst comes to worst, and the crank journals are scored, any competent machine shop can turn it smooth again & recommend the correct replacement bearing size.

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PostPosted: February 9, 2017, 9:48 am 
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To be on the safe side, "a lot more work" I would completely dis-assemble the motor, to make sure there is not some else screwed up in the assemble process which cause the shavings. Once apart clean and flush out the oil pump and oil passages. I've seen a small particle block a cam oil port, which cause a cam journal seizure. Broke the cam in two, which then distroyed the valves, pistons and head. Dave W


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PostPosted: February 9, 2017, 10:25 am 
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Inspect the cylinder bores for signs of scrapping. Some filings are normal in the break in process and normally come from the rings when seating.

do you know if the re builder was using a quality break in oil?

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PostPosted: February 9, 2017, 9:25 pm 
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Got the oil pan off and everything looks pretty clean. There was only 2 or 3 very small pieces of metal on the oil pump suction screen.

I realise the title of this thread is very misleading. I bought a junk car strictly for the motor. The car will be junked except for the usable parts. Some of these parts will be on my locust.The motor is still in the car. I want to correct (if needed) and bearing issues and get the car to fire up. Once that happens, I will pull the motor. This is just a test to see if the motor is free of any other issues by test driving it.

I have decent access to the bottom end. I can easily get to all the Rod bearings. It's a struggle, but possible to do the main bearings. I'm planning to remove one bearing set at a time and take a detailed picture of each. Post it up here for the real pros to decipher it.

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PostPosted: February 10, 2017, 12:17 am 
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Don't guess, use plastigage on all bearings, one at a time.

Tom

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PostPosted: February 12, 2017, 3:28 pm 
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I think the only way you're gonna have peace of mind is to do a tear down.

With luck -- verifiable with $4 worth of plastigauge and your eyes and fingers -- the rod and main bearings will be good. And with luck -- verifiable with your eyes and fingers -- the cylinders and pistons will be okay. And when you have that head off, you can do a quick leak test of the valves (a few dollars for carb cleaner ought to do it). And as suggested, before putting it back together, a quick $5 trip to the local car wash to use the hot high pressure water to blast out the block will make sure no more shavings are hiding. Wash down all of the parts before re-using of course.

So unless you find a problem in there, this is mostly time and pocket change, and not a lot of either. Besides, you can learn how to rebuild a non-rotary in the process?

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PostPosted: February 12, 2017, 4:42 pm 
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It's more about time. Bearings and gaskets are cheap. Time is rare.

Well.... I pulled the first bearing cap from one of the rods. It's scarred decently. I can definitely feel it. Both the Rod side and cap side have grooves in them. I didn't bother to look at the rest yet. I'm deciding on wether or not to pull the motor.

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PostPosted: February 12, 2017, 4:44 pm 
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sen2two wrote:
Well.... I pulled the first bearing cap from one of the rods. It's scarred decently. I can definitely feel it. Both the Rod side and cap side have grooves in them. I didn't bother to look at the rest yet. I'm deciding on wether or not to pull the motor.


And correspondingly (and more expensively) is the crank got a groove in it now?

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