Prep Engine Block Deck and Cylinder Head Mating Surfaces for New Gasket

[jhicban]

Any tips, dos, don'ts, for mating surface prep for new gaskets? I am doing prep work before re-installing cylinder head onto engine block... Mind you, this is a cast iron block.

From what I've read, there seems to be heated debate about what is the best way to clean and prep each surface.

Here's what I've read/viewed:
1. Some say use 3M Scotch-Brite Roloc Bristle Disks attached to a drill, others say never use because you can round off edges of the deck.
2. Some say use 3M Scotch-Brite Scouring Pad (red or green), others say never use because you can scratch the surface too much.
3. Some say use a wire wheel on a drill, others say this is too aggressive.
4. Some say use a blade scraper, others say not to because you may gouge the surface
5. Some say to use fine grit sand paper and a sanding block, others say it makes for too much dust and particles that can get "into the engine"
6. Some say to spray shaving cream into the water jackets and various holes in the block to prevent particles from falling into the holes

I have noticed so far in examining the engine block deck.. there is hard crusty buildup in the holes of the engine block deck... some is dark black, some is light brown in color... I imagine pieces of this crusty stuff will easily fall into the holes when scraping, scrubbing... here are some pics:

IMG_1292.jpg IMG_1293.jpg

[Chipmaker]

I use a putty knife aka a painters knife,sharpened on the end with the corners rounded off.If I need to prevent the trash from going into the engine I hold the end of a shop vac. next to the scraper.

to sharpen hold putty knife at about 20 to30 degrees on the side of a grinding wheel.Dont hurt to finish with a few strokes on a oil stone.

[BRUCESTUDE]

I use a razor blade type gasket scraper (with a shop vac as Chipmaker sez) then I follow with a blue Scotch Brite sponge/pad (doesn't scratch) with a little solvent on it followed by a rag and bare fingers to check for any spots I missed.

[Hawkowner]

I like wet and dry sand paper with mineral spirits or stoddard solvent.
Hawkowner

[StudeRich]

Do not worry too much about getting whatever abrasive you use into the Water Jacket Holes, it is easy to knock out a Core Plug and flush it out.

What you need to be concerned about is getting debris into those Push Rod Holes and into the Crankcase!

The other place to keep very clean is in the cylinders, as debris will lodge between the Piston and Cylinder Wall.
You could try sealing that gap with wheel bearing grease. Carefully removing it when finished should take a lot of debris with it.

[Mike Van Veghten]

Sharpened scraper.
New razor blade for stubborn areas.
Clean rag with lacquer thinner to finish.

Just don't go crazy with what-ever you use. Use care because most everything mentioned can...damage the deck surface. I would NOT use any sand paper of any kind, unless it's mounted to a hard, flat block of some kind. Like maybe a body tool, and even then, use great care to not use it like a rag (short strokes)...use it like you were carefully sanding (long strokes) fresh Bondo and preparing for paint..! Then "lotsa" cleaning.

Mike

[Dan Timberlake]

https://gm.oemdtc.com/1895/00-06-01-...ars-and-trucks

A lot of "don't do this" without any "DO do this."

[swvalcon]

I just put a sheet of 40 grit on my air file and hit it once over. Makes it look like new.

[jhicban]

Hey all,

Finally got a chance to scrape clean most of the deck/mating surface in preparation for the new head gasket. As I chipped away of some of the buildup accumulating in the holes may have fallen through some of the holes and into the block. Any tips on how to get that stuff out? Some videos I've seen say to use compressed air to blow it out of the bolt holes. Would this apply to the oil galleys and coolant passages?

Thanks!

[DieselJim]

If the water jacket has not been cleaned, remove the freeze plugs and wash years of rust build up in the rear of the block. Blow out the bolt holes but NOT the oil pressure holes.

[Colgate Studebaker]

This may be a little late but when I do the clean up of a block I go"nuts" with paper towels or rags to cover everything in the lifter valley and then use torn off pieces of paper towel to "fill" every hole that something could get into. I just push enough towel into the hole to prevent gunk from falling into the hole and getting into the oil or water systems. After I am done scraping I use the shop vac to suck up as much loose stuff as possible, and then one by one pull the paper towel out of each hole as I vacuum right next to it. (The vac usually sucks up the towel as I pull it out.) This method usually leaves no residue in any of the block holes or oil and water systems. Bill

[jhicban]

I'm pretty sure the water jackets have not been cleaned in many years.

Also, the engine is still in the vehicle w/ the cylinder head on the bench. Looks like I may be able to get a long screwdriver to reach the freeze plugs from underneath or through the wheel well. I almost didnt notice them as they were covered with gunk.

Once removed, what can I expect? Most of the fluids have been drained. Any tips on flushing the block?

[55 56 PREZ 4D]

Once removed, what can I expect? Most of the fluids have been drained. Any tips on flushing the block?[/QUOTE]

Yeah.
Get ready to get dirty, wet. Oh so dirty and wet.
Do it outside, vehicle on some kind of lift, so you can move around.
Wear rain gear, gloves, boots, hat, eye protection, plus any other coverings you can think of. Tape around the sleeves.
Just flushing with water won't be enough. You will need to poke and scrape and manually free crud loose. Get creative.
I made an adapter from my hose to a piece of brake line. Bent so i could direct water around the back side of the cylinders and into all the knooks and cranies.
Remove the plugs on the sides at the back of the block, they will give you another entrance to poke and flush.
After you have flushed the block and replaced the the plug and closed up the system, use a flush kit or one of several homebrew methods to remove any left over crud.

[BRUCESTUDE]

A pressure washer works good too, I did a Stude V8 on an engine stand this way.

[SilverHawkDan]

Something I do not see mentioned is very important. You "Must" run a bottoming tap into each and every head bolt hole and then spray with brake or carb cleaner and then finish with air. Wear eye protection of course. #1 cause of head gasket failures on in car head gasket jobs is dirt and debris in the bolt holes. Can cause the head bolts to give you a false read when torquing then down. If there is enough debris the bolt could actually bottom in the junk and not get tighten even close to specs. With modern gaskets the next for re-torquing is all but gone so getting it right is the best thing you can do. I also use the cold valve adjusting method with TDC and 180 crank settings. Look on the web for Chevy valve adjusting sequence and print it out. They share the same firing pattern with our Stude's. Or if you can't find it PM me and I have it saved in my computer. I make sure all our race cars have a metal plate with the sequence riveted under the hood for easy reference. Also make sure you wire brush each head bolt and check the threads. Usually not a problem with Stude's as they do not thread into water passages.
Dan

[TWChamp]

I use hardware store bolts, and my Dremel with a small cutoff wheel to grind 4 slots in the last inch of the bolt, then use this to clean out the block thread pockets.

[jpepper]

Taps have a size on them. There is a number on the shank that denotes the amount of pitch line oversize. This is a GH number. Each number step is .0005" . Thread chasing/cleaning taps are usually GH-3 which means they are .0015" oversize. Do not use a tap larger than this for cleaning purposes. Regular taps can be GH-5 or GH-7 depending on the desired thread fit. I used to use GH-14 taps for machining 8620 steel that was going to be case hardened. The holes would shrink during the carburizing process so they had to be tapped oversize prior to heat treat.
here is a link http://www.tapmatic.com/tapping_ques..._h_limits.ydev
You can buy a 5 tap set of cleaning taps from ARP and other companies through Jegs or Summit racing. You might also be able to buy them from McMaster Carr. A basic set is 1/4-20, 5/16-18, 3/8-16, 7/16-14, and 1/2-13. My point in all this is not all taps are the same. Use the correct ones for thread chasing and cleaning so you do not ruin a good block or head.
By the way, I clean the surface with a flat scraper and wipe with Acetone, lacquer thinner, or brake clean.