Dirty Crankcase Drama

stevieb49829 · Apr 22, 2023

After pulling the pan, I didn't have much hope for making this easy, or cheap:

But then I braved pulling the center main cap, and there is hope:

If the other bearings look this good, all I'm stuck with is a LOT of cleaning, and new bearings. The top end looks good enough to run as is, at least for a while. But if I have to pull the pistons to get it clean enough, I'll re-ring it too. steve

rustred · Apr 22, 2023

i dont see the brg there. thats the crank journal and it dont look to good. seeing the brg. also tells a better story.

Fritz Maurer · Apr 22, 2023

If that is all just soft sludge, get a case of brake cleaner from auto zone for about 45$. Stand it up on end and pressure wash the loose gunk off it if you have one. Then hurry and spray the brake cleaner on it for final cleaning and to keep it from flash rusting. The cam should slide right out. If it doesnt, dont force it or you will ream out the center bearing. If it absolutely has to come out, you need to get in there with a small file or die grinder and clean the burrs off the gear teeth til it fits through the bearing. If the clearance is good with new bearings, that crank will clean up nice with some 600 grit.

rrlund · Apr 22, 2023

get a case of brake cleaner from auto zone for about 45$.

Plus you get the fun of getting a little loopy from the fumes. LOL

ss55 · Apr 22, 2023

Was the engine under water in a flood? Sand and silt get everywhere.

Muir hill 101 · Apr 22, 2023

Hopefully its just the photo and the journal will Clean up with solvent

stevieb49829 · Apr 22, 2023

The journals just have spot stains on them, but little to no roughness. I'm working on comparing the desired specs to actual mic measurements, but I think I'm really close to the limit on oil clearance. Luckily there are undersize (actually oversize) bearings available at .002 that might fit the bill to take up that slack. I need to get the crank really cleaned up and do some precision measuring. Then I might just polish it up, get my bearings, and plastigauge the heck out of it. steve

stevieb49829 · Apr 22, 2023

The bearings are smooth, but they have pockets where there is no babbit. Not sure how that happens without tearing up the crank journals or the surface of the bearing, but almost all of the rods and mains have pockets of missing babbit. It looks almost like it was etched away with acid.

stevieb49829 · Apr 22, 2023

ss, that's just ash build up, and some sludge. No flooding was involved.

rustred · Apr 22, 2023

i wanted to see the wear in them , that tells the story right there. u cannot put .002 undersize in as the crank will not turn over. i know i
have been there. did you plastigauge the brgs. ? or at least you should have. , that tells the story also. lots of mechanic's here but we
never get the proper info on stuff, then ask what we think well it takes info for your answer. not being a smart azz either, just saying, as
i am a red seal ticketed mechanic. that is why i avoid electrical posts as there is lots of qualified electricians here . same with plumbing. and i will not say maybe this or maybe that. i know what i know .

stevieb49829 · Apr 22, 2023

It's not soft sludge. It's cooked on carbon. I tried some brake cleaner-didn't do a thing. I can get the block hot tanked, but crank, cam, lifters, gears etc are going to be work unless there is a solvent that will cut through this stuff. steve

stevieb49829 · Apr 22, 2023

RRed, I'll post some bearing pics tomorrow. And I did think about the plastigauge as I was tearing it apart, but didn't have any fresh on hand. I can still do it, but my measurements say I'm in the neighborhood of .005 to .007 of oil clearance on the rods, and a little less (.004-5) on the mains. That's comparing the mic'd journals to the specs. They do seem to be consistent all the way across the bearing surface, except the number 1 rod journal. It varies about .002 across.

stevieb49829 · Apr 22, 2023

Here's some back story, for those who want more info. This engine has not run for many years. I don't know how many but probably more than 20, or 40!! I got it from a guy that snagged it out of 101 Jr. from a scrapper at an auction, then he took it home and stored it. I'm really surprised it still turned over, but he did pour the oil to it before storage. I do wish the previous owner had changed oil in it. I'm thinking that's where all the baked on carbon came from. I'm not above turning the crank and putting new bearings and rings in it, but I'd really like to find a way to clean the carbon out of it without scraping every square inch of the crankcase. The smoothness of the journals made me happy, until I started comparing measured to published specs. The bearings were smooth, but they are so old and unused, they're no longer shiny like they would be in a running engine. I think I might go back and torque a couple of rods back on the crank with plastigauge, and see if my measurements are suspect. Steve

used red MN · Apr 23, 2023

I was going to shock everyone and suggest pressure washing it, but much to my amazement Fritz recommended it!! I was going to say find a way to pressurize the lube circuit to pump in fresh lube. Once lubed, wash it then pump in another round of new lube. And if the crud does not come off easily as in it is stuck pretty good then who cares leave it in there and run it. It will come out in the oil when it is changed if the detergent additive can cut it.

BarnyardEngineering · Apr 23, 2023

(quoted from post at 22:42:30 04/22/23) I was going to shock everyone and suggest pressure washing it

That's how they do it at the machine shops these days. EPA won't let them use the old caustic "hot tank" anymore. "Engine washers" these days are water based, just a glorified oversized dish washing machine.

Gary Mitchell · Apr 23, 2023

I wouldn't let those pockets concern me too much, (unless they're big or very non-
uniform). Some bearings have actually been made with multiple little dits to hold oil in
the bearing for better lube. An old time puller friend used to make the inserts on his 460
that way for increased oil retention at the crank surface. gm

Dirty Crankcase Drama

stevieb49829

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rustred

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Fritz Maurer

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rrlund

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ss55

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Muir hill 101

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stevieb49829

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stevieb49829

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stevieb49829

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rustred

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stevieb49829

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stevieb49829

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stevieb49829

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used red MN

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BarnyardEngineering

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Gary Mitchell

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