Best way to clean out water jackets

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Big_Al

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I am building a 360 and I need to half fill the block to stiffen up the bottom end. What is the best way I can clean out the water jackets?? How clean do they have to be when I fill it?
 
Screwdriver and hose through the cup plug holes. Break the solid stuff loose and flush it out with water.

Remove any blockage that you can.
 
30% pool acid to water fill. Pour in, start motor for 15 mnutes and drain, dump a box of baking soda into 3 gallons of water, run then drain. backflush. repeat if necessary. Works great on radiators too, just dont let sit more than about 15 minutes in radiator at a time.
 
If it's down to a bare block just pull all the frost plugs and get after it with a pressure washer. If you make it back in the house and are only halfway soaked then you didn't do it right, lol.
 
decades ago I remember a post from Doug Dutra the /6 guru & he filled a bare block with a percentage of muriatic acid (the pool cleaning acid mentioned I am assuming) and water & let it set & said the insides came out looking like freshly machined metal? I dont remember what percentage he used & iirc I think he let it set overnight. if it needs to be squeaky clean for the block fill to adhere I would check into that. As you know on these deals (painting/gaskets etc) surface prep is everything.
 
I rat tail filed my block and blew it out while on the engine stand. Incredible how much crud built up over the years in the jackets.
 
Muriatic acid...the only way to do it...its what everyone uses before filling a block the right way.

Just make sure you have lots of ventilation and hose to get rid of that **** asap...but it will clean the water passages spotless and make it perfect for some block fill to stick to!

Good luck!
 
So stupid question - you all that leave stuff in overnight - do you leave the freeze plugs in?
 
there are no stupid questions. yes freeze plugs in so you can fill er up to the level it needs to be filled up to (I've never did hardblok)
 
muriatic acid...the only way to do it...its what everyone uses before filling a block the right way.

Just make sure you have lots of ventilation and hose to get rid of that **** asap...but it will clean the water passages spotless and make it perfect for some block fill to stick to!

Good luck!

x2
 
Did a search and found these two quotes related to Doug Dutra, the first with a link her to the entire article.

http://www.slantsix.org/articles/dutra-blocks/slant-blocks.htm

"A comment on block cleaning: First remove all the plugs and get the blocks "hot tanked", then take a close look at the water jacket area. If the water jackets still have rust, scale and casting wires inside, you may want to "acid soak" this area to get them spotless. You have to plug up all the openings, then use a strong solution of sulfuric or muriatic acid (swimming pool acid) to "etch out" all the crud, including sintered core sand and core wires left behind from the casting process. Doing this will remove unneeded weight, increase coolant flow and will keep your cooling system / radiator clean. You can also spot any casting problems easier when the block is completely clean."

"Doug Dutra is the expert on this. He seals up the block using a head and gasket along with rubber expansions plugs. Then he sets it on end with the water pump cavity up. Then he fills it with a stiff solution of water and (In order of effectiveness) sulfuric, muriatic or phosphoric acid. Let it sit for a least 24 hours, if the solution quits bubbling before that, drain and refill. Now drain the block and refill with a neutralizing solution of baking soda and water. This procedure should leave you with the cleanest water jackets in town. If you are going to use a block filler be careful not to let any oil or WD-40 get on the inside surfaces."
 
The "best" way, which is what you asked, is to take the block to the machine shop.
 
The "best" way, which is what you asked, is to take the block to the machine shop.

I doubt they are going to take the time (or the customer is willing to pay for the time) to physically pick away at the scale in a block much than right at the freeze plug holes.

You can acid and chemical wash and even pressure wash to your hearts content. But large scale needs to be physically picked out the block.

If you are going to half fill it, I'd really make sure the remaining water passages were spotless.

long screwdriver, coat hanger, radiator hose pick, etc...and your hard work, patience, and attention to detail.

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The next time I get one cleaned, I will take pictures. The big shop I use sometimes in Macon has a new BIG ultrasonic cleaner that uses a liquid with abrasive in it. I have not had one done yet with it, but have seen the results. Aside from any pitting, when it comes out, it looks like brand new metal, inside and out. I've never seen anything like it before. This particular shop does a LOT of OTR trucks and industrial engines.
 
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