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How To Final wash an Engine Block

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BogusSVO

10+ Year Contributor
5,891
318
Jul 1, 2009
Pensacola, Florida
How to final wash an Engine Block

You just picked up your block from the machine shop, and your ready to build your engine.
The block may look clean, but it is not.
It still has grim and grit from machining in it.

It is up to you as the builder to final wash the block.

First gather together what you will need to clean the block.
Lint free paper towels, WD-40 , a good degreaser and a can of brake cleaner.
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Now find a place to wash the block, a table or engine stand will be fine to use.
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Now spray the degreaser all over the block, take good care to get the inside of the block and cylinder walls.
Let the degreaser work for 15 to 30 minutes, Do NOT let the block dry, reapply as needed.
Now spay the block down with clean water till the water runs clear.
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Now quickly blow the cylinders and main bearing saddle surfaces dry with compressed air.
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Now spray WD-40 in the cylinders and main bearing saddle surfaces to prevent rust.
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Now spin the block around and spray brake cleaner into the oil galleys, I would recommend that any oil galley plugs be removed for this step if they were not at the machine shop. Just make sure to install them back.
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At this point, take compressed air and blow through all the oil galleys,

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main and head bolt holes.


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Repeat till all signs of grit and old oil is removed.
Now take a couple paper towels and fold into ¼ and spray WD-40 on them, soaking them well.
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Now wipe the cylinders down
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Look at the paper towel now. This is hone stone grit and rust. Leaving this in the cylinders can cause issues with the rings glazing and not sealing.
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Keep flipping and folding the paper towel and soaking with WD-40 until the paper towel comes back out clean!!


Now look in the corners inside the block and in general give the block a good look over for anything missed.

Make sure any oil galley plugs that were removed are replaced.

You can not get your block too clean!!
 
Great write up dale. Yea the block and rotating assembly needs to be hospital clean. WD 40 is very important in cleaning and protecting as it pulls the crap out of the pores of the metal to get wiped away.
 
I wish you made this before my engine rebuild LOL. If you remember correctly you told me the correct way about 4 months ago when I started my rebuild.

I also went out and got a engine block cleaning brush kit from a smoke shop it was cheaper for a hookah brush cleaner then engine brush kit go figure and there the same thing.
 
Glad its getting some use then!

GSX.. I knew there was a reason I wanted to do this one! LOL
good Idea on the smoke shop.... I use a gun brush kit, cheaper also, and you can get brass/copper brushes for the bad areas.
 
This is excluding if you hot tanked it correct? Everytime I get my blocks hottanked they are spottless.
 
This is excluding if you hot tanked it correct? Everytime I get my blocks hottanked they are spottless.

Machine shops hot tank, or jet wash them before they machine them. They need cleaned afterward before being put together. Even if they are hot tanked after machining, you still need to blow out the oil passages with air and wd40.
 
I always tell them to hot tank it. I always get charged for that seperately. I guess I always assumed they just hottanked it afterwards as well. I guess I will have to call to confirm.
 
A good oven cleaner is one of the best De-greasers you can use for cleaning the block. Caution though, do not leave it on for more than 15 minutes. And make 100% sure you wipe everything down with WD-40 as stated. The oven cleaner will get it spotless and it will rust very very fast.
I also suggest using Coffee filters if you have to wipe anything down. They wont leave anything behind!

One of the more crucial steps also is making sure all debris is out of all bolt holes. What i do is fill each bolt hole with WD-40(preferably using the straw) and then use the air nozzle to blow everything out. Also If you are rebuilding these things constantly then it is a good idea to have all the correct size taps and run the tap down the head bolt areas. Even if there is nothing wrong with the thread's do it anyway.
This goes for most of the other bolt holes as well(Mains/Cam caps etc etc)

Also if you get the block back from the machine shop and it still has freeze plugs in it then remove them. This will help in getting all the coolant passages clean and never trust old freeze plugs anyway, replace them. Normally I knock all the freeze plugs out before I send one to the machine shop.

Another important step, Don't drop the motor in the Dirt!
 
yes, having your block cleand at the shop, hot tanked, or spray washed removes the heavy grit, grime and oil, and yes it is probly done after machining (most of the time in the same tank or cabnet that was first used)

think of how many heads, blocks, cranks and misc parts are cleaned in the same tank or spray cabinet. Then think how often that tank or cabinet is cleaned (about every 6 months or so) and about 20 gallons of sludge is scooped out the bottom of the tank.

I know this beacuse for many years I have been the one to clean it out! Its a very nasty and time consuming project to do, then when refilled it takes about 24 hours for the water/chemical to come back up to temp

yes SOME shops may have a before and after tanks, but not many

so yes YOU MUST final wash the block, and all other parts.

I would be willing to bet the reason most rebuilt engines fail, with spun bearings, is for the simple reason that the block and crank were not final washed, before they were assembled and some small amount of grit/grime worked loose and hit the bearing.
yes oven cleaner works well for the first cleaning of the block.
 
Great write up! Perfect for people who has never dealt with bare blocks or disassembled motors.

So when I cleaned the bearing saddles in the block before installing the new bearings I used brake cleaner and compressed air to make sure it was nice and dry and free from dirt. My motor still had all components except for main crank bearings, rod bearings, front case/oil pump, and timing belt components so I couldnt do that much cleaning. I see you said to spray the main saddles with wd-40. Before installing main bearings do you spray off the wd-40 with brake cleaner or leave the wd-40? Wouldnt you spin a bearing by not getting rid of the wd-40 on the saddles? Sorry for the ignorance but I have never done auto work into detail as assembling internals of a motor. Thanks.
 
no, WD40 is used to stop rust, wipe it off right before you install the main bearings
also, No wd40 will not cause the main to spin, a small amount of motor oil will work behind the bearing when the engine is running, there is a slight "press fit" when the mains are torqued down normally less than .0005
 
Actually ATF works better when wiping the cylinders down for cleanliness compared to wd-40. Try it.
 
I also agree with trans fluid. That stuff cleans great and also fills the pours with lubricant safe for assembly, though you wouldnt want ATF mixed with eng oil but id assume doing everything as stated, sealing the deal with ATF in the cyls, then wipe them clean with no solvent to then assemble.
 
Bogus, I was taught to use hot soapy water and brushes to clean the block. I use a cylinder brush and a galley brush. Is that not good anymore? Or is this a improv method for those without all the tools?
 
G-unit & Flexnuts, If ATF works for you, then go with what you know, the main point is to prevent rust and remove and grit/grime and maching residue.

Bastarddsm, Hot soapy water works just fine still, I agree "gun Brush" any and all oil galleys you can get to.

You can never get an engine too clean for assembly.

I post the ways I know and use and have been taught over the years, by no means dose that mean it is better.

Some of the "how tos" I post are for the first timer building there first engine, and just do not know.
 
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