How does everyone go about cleaning their dirty, nasty engine block? It's all apart right now, just waiting to get cleaned so I can paint!

 

Have it boiled at a machine shop...

 

I have been using oven cleaner on the iron blocks, works very well, better if you use a scrub brush with it. Then pressure wash afterwards

 

Are you rebuilding the engine?

 

Yep, just refreshing it up a bit. New bearings and piston rings.

 

As in post #2, have a machine shop hot-tank it. Removing all the core and oil gallery plugs and dunking it is the only way to get an old block clean enough to rebuild. The oil galleries, in particular, must be absolutely clean.

When you get the block back from the machine shop, with all required machine work completed, wash the block with a bucket of very hot water with laundry detergent mixed in. An assortment of bore brushes is necessary to clean all the passages. Even one small piece of grit or metal left in there will find it's way to those new components and cause problems---either sooner or later. Rinse the block of soap, blow it completely dry with an air pistol, and coat all the machined surfaces with clean oil.

A clean plastic trash bag will keep the block clean until time to build it.

 

If you are not going to go as far as ironwill said, then take a pocket full of quarters to your local car wash late at night, blast it there and leave them the mess. You can do the oven cleaner also, but definitely bring a can of WD-40 to prevent instant flash rusting.

 

Machine-shop cleaning first, along with whatever work the block needs such as boring, honing, align-boring, decking, etc.

Have them leave all the oil passage plugs and cam bearings out and go pick it up like that.

On a nice hot sunny day, take it to the quarter car wash first thing in the morning, along with acoupla cans of "engine degreaser" (diesel fuel in a spray can) and your full set of rifle cleaning brushes. You'll need the .22 and .410 brushes mostly. Run the brushes through EVERY oil passage in the block: the one from the rear main cap to the oil filter (you'll need to clean it from both ends), the vertical one up the back of the block from the rear main cap to the oil pressure sending unit, the 3 front <-> rear ones next to the cam, and the 4 vertical ones from the main bearing journals to the one above the cam. Use a toothbrush-shaped wire brush to clean the grooves behind the cam bearings. Wash the cyl walls THOROUGHLY with a rag and/or a brush if the bores got bored or honed. Leave the block outside in the sun to dry for several hours. Coat the cyl walls, lifter bores, and main & cam brg journals with some kind of oil, when dry. Use a lint-free rag to wipe it on which will take care of any minor surface rust.

Paint it. I suggest using marine primer or LPS "cold galvanize" and engine enamel. PLEASE don't paint it that ugly red-orange from the 60s... I like the Mercury Marine "charcoal metallic" myself, or alternatively you could use the stock satin black.

You can use a giant plastic bag to keep it clean during transport; a lawn clippings bag will work, or you can use [gasp] the right thing - an engine bag - [/gasp] such as from a speed shop type of place.

Take it back to the machine shop. Have em put the plugs & cam bearings back in. Wipe the cyls, main journals, & lifter bores with lacquer thinner, and use spray can carb cleaner on the cam bearings, just before assembly. Wipe the decks with the lint-free rag to remove rust from them before installing the heads, followed by lacquer thinner.

 

That is an EXCELLENT idea! I didn't even think of that. I bought some generic engine bore brushes and if they fit and work properly, they are still too short to go through the main galley. The others are the wrong size to get in all the holes. Looks like I am buying another dedicated cleaning rod and bore brushes

 

Just dropped the block off at the engine block off at the machine shop. Thanks guys

 

Thanks scooter.

I should also mention, run a thread chaser through all the head bolt & WP bolt holes, before the car wash experience.



Here's a diagram of the oil passages in a SBC block. The yellow, green, red, & horiz blue passages are .410 size; the other vertical ones are all the smaller size. Magenta is the push rods: ignore those for the purpose at hand.

Doesn't hurt to do this to the crank as well. The light blue ones in the diagram are in that. Personally I usually polish crank journals after grinding with 2000 grit sandpaper and then crocus cloth, after which it needs a thorough cleaning with the .22 brush and all that, as well; then oil (ATF works great) on the bearing & seal surfaces.

I don't know who I ganked that dwg from but it's a pretty well organized upgrade to the stock one that comes in various GM publications.

 

I chase all my fastener holes too, surprising how much stuff can come out of them.

Thanks for the diagram, but I mostly do LS engines now, minus the two BBCs I have left. Unless the passage sizes are the same? I can go out there with the verniers and figure it out too. The main galley passage is much different than the lifter bores, I didn't feel great about how I left those, but it should be fine. I cleaned it more than twice