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PostPosted: November 3, 2016, 10:50 pm 
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Joined: July 24, 2008, 9:18 pm
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I have this motor that turned out to have a bad bottom end. So I sourced a lower milage (40k) short block. I do not plan on rebuilding it unless I break it in the future. The motor has no issues besides being a little dirty.

What is the normal process of prepping a short block?

By this I mean, how to clean it internally and externally? Making sure oil passages are free of debris? Same goes for the coolant passages. Using a honing stone (that I would normally use on my Bridgeport Mill table) to ensure a flat surface on the deck? Etc.....?

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PostPosted: November 3, 2016, 10:53 pm 
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Joined: June 8, 2010, 8:02 pm
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What kind of motor? Makes a big difference :mrgreen: .

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PostPosted: November 4, 2016, 9:38 am 
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C10CoryM wrote:
What kind of motor? Makes a big difference :mrgreen: .


6g72.... Mitsubishi V6

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PostPosted: November 4, 2016, 10:02 pm 
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You're going to need to tear it completely apart to do most of that.

If it were me I'd drop the pan, clean out any sludge, and make sure nothing looks out of place (metal flakes, discoloring from heat, etc). Be careful to keep dirt out of the engine. Once it's assembled I'd clean the outside with engine degreaser.

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PostPosted: November 4, 2016, 11:56 pm 
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If the "new" shortblock is freshly apart just treat it like a cylinder head R&R. Typically means cleaning the deck with a bristle-disc and checking for warping with a straight-edge. If it's flat, put it together. I always suggest pouring a liter or two of oil through the heads and then drain it out before starting for the first time (or the valley if a wet-valley). This really helps clear the debris out from the oil passages and is well worth the $10 in oil. If you are concerned about contamination from the shortblock sitting while apart, it's really the same scenario or tear it down and rebuild. You'll not be able to clean much while it's assembled and can even loosen up some carbon chunks that will block passages.

Cheers.

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PostPosted: November 5, 2016, 9:44 am 
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Please don't use power tools to clean gasket surfaces, that is what flat rate mechanics do.

Scraper, razor blade, then finish with a stone and WD-40.
Use a shop vacuum to collect debris as you scrape.
WD-40 will trap the stoning debris.
Wipe down with clean towels to remove finish debris.
Spray with carb cleaner and wipe down again before assembly.

Do not invert a used motor until oil pan has been removed!

If you are THAT worried about dirt, take the whole thing apart and wash it.

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PostPosted: November 5, 2016, 9:30 pm 
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Bent Wrench wrote:
Please don't use power tools to clean gasket surfaces, that is what flat rate mechanics do.

Scraper, razor blade, then finish with a stone and WD-40.
Use a shop vacuum to collect debris as you scrape.
WD-40 will trap the stoning debris.
Wipe down with clean towels to remove finish debris.
Spray with carb cleaner and wipe down again before assembly.

Do not invert a used motor until oil pan has been removed!

If you are THAT worried about dirt, take the whole thing apart and wash it.



That post is BS. First because it insinuates that I am a flat-rate mechanic when I am a hourly mechanic who follows the philosophy of doing what is in the customer's best interest (so they keep coming back). Happy customers means repeat business which means success. And second, because it is utterly wrong.

The reason why most mechanics use 3M Bristle-discs is because they work very well, and because it is what many manufacturers recommend. I know for sure off the top of my head that GM, Nissan, and Toyota recommend using these. I am sure there are others. Most modern engines (including the one OP is playing with) use shim gaskets. These leave very little junk on the surfaces to clean. Using discs properly will remove the junk and still leave the factory machine marks without introducing harmful contaminants. You are not going to improve on that by scratching the deck with a razor blade and unevenly removing the factory machining with a hone. Nevermind introducing abrasive stone material, carb clean and WD40 into your oil/coolant passages and cylinders. The correct procedure is to clean areas around headgasket (1" above/below), remove head & gasket, wipe off any junk (away from the cylinder/passages), wipe with brake-clean/rag, bristle disc, then wipe again with b clean/rag. You are now ready to check for surface flatness and re-assemble. Once the heads are on, pour a few liters of oil over the valve train so it drains through the passages. This will flush the junk into the pan. Then drain the oil to get the junk out. If you think a bunch of coolant ended up in the pan when you pulled the head, start the engine for a minute then change the oil/filter again. If you think a bunch of oil got into the coolant, flush it out with water before refilling with coolant.

If you bought the new engine with the heads already removed you may want to check the bearings for coolant corrosion. Meaning someone may have pulled the heads, let coolant get into the oil, and then let the engine sit. Coolant will eat away bearings very quickly.

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