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Cleaning the block deck before new head gasket (6.2)

8K views 40 replies 7 participants last post by  dkrajisnik 
#1 ·
Now that I have that dang bolt out I'm looking into how to clean my block deck a bit before I get a new or resurfaced head on there.

Looks like there is a lot of carbon build-up, rusty residue and residue from the head gasket. Both on the block and inside the coolant passages.

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Someone mentioned Diesel Mechanic in a bottle is good to help clean the pistons. Do I need anything else for cleaning the other residue? Also, would I use any sort of high-grit sandpaper or emery cloth or just apply it with a cotton rag or microfiber cloth?

Should I bother with trying to the coolant passages manually at all or would the Cascade coolant flush be enough once it is re-assmbled?

Finally, is it a good idea to chase the threads for the head bolts?

Thanks guys. You all are a lifesaver for a newbie like myself.
 
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#2 ·
Definitely chase the bolt holes. They were sealed as they are through the deck and into coolant passages.
Do NOT use sandpaper. Grit will get into the crown gap and get into the rings. Unless you can seal the bores and keep it clean, use gasket scraper and solvent or gasket removing compound.
Now you can safely use a file to knock off high spots, these will be rust, embedded fire rings and gasket metal. Stuff clean towels in the bores. Any dirt going into oil or coolant isn't an issue.

I've found certain peanut can tops, those flexible snap tops, can fit certain cylinders and keep things cleaner. Always mind the crown gap for dirt as it is impossible to clean unless removing pistons.
 
#3 ·
Thanks for the reply!

Do you know the TPI for the head bolts so I can get the right chase tap? If not, I'll likely buy a kit.

As far as the gasket scraper, do you mean a plastic one or one of those that's basically a razor blade mounted flat on a handle? Any particular solvent or gasket removing compound that's recommended?

I'm a bit worried honestly that in the process of removing that stuck bolt, some metal filings from the bolt might have gotten into the bore. I didn't file or sand it but just gripping it with the vice grips, it's visible that a lot of material was chipped off the bolt body. Not sure what to do here really other than vacuum carefully. Compressed air? But maybe that would just jam anything that's in there even tighter.
 
#4 ·
Use a fine wire wheel on a drill to remove debris from the deck surface.That’s the quickest way to do it.Stuff rags in the cylinders and the lifter area so nothing gets down there.

When everything is clean remove the rags and wipe out the cylinders.Rotate the engine getting a piston up to TDC and use a shop vac to suck up particles between the piston and cylinder wall.
 
#5 ·
Best thing to do is use a old head bolt and cut three deep slots in the thread area to act as a thread chaser.Works out perfectly and costs you nothing.
 
#6 ·
I like the bolt as a thread chaser idea. Clever. I'll probably start with a plastic scraper then move on to a metal one then the wire wheel.

What about the inside of the cylinder walls? If you look in some of the pics, there is some rusty residue on those as well. I'd assume that's an even more sensitive area than the deck.
 
#7 ·
Glycol brake fluid works on most gasket compositions. Definitely use the razor blade scraper.
A fine wire wheel cup in a grinder also works for cast iron. Meaning not for pistons.

I wouldn't worry about the bolt fragments, vacuum and solvent would work to clean. Now on the head, I have some Nylon bristle brushes with very fine abrasive molded in the Nylon. Does a very fine brushed finish on stainless and cleans cylinder heads well.

The rusty cylinder will polish itself out, wipe off as much as possible. It will hold oil so it may burn more but it won't be severe.
 
#9 ·
Usually a brass brush in a small drill with a light touch and a combination of what has been mentioned depending on conditions.

....shop vac being critical. and even tape to collect particals....like folded duct tape to grab dirt.....I usually have a ball of it to keep my hands clean while working....seems counterintuitive...but I have had good luck with it.
 
#12 ·
I would personally not use any wire product to clean a diesel cylinder deck. I have found 3M Bristle Discs work very well and give a polished surface with no scratches. I put a piece of foam tape in a circle, cut to fit inside the bore to seal the gap at the piston (I dont use the adhesive tape), and pack a rag in the cylinder above the piston, keeping it below the deck, and polish away with a 90 degree die grinder. High RPM and light pressure will give an exceptional finish. They also have the disc holder on Amazon. You will be amazed how the rubber fingers clean metal. There are videos about this on YouTube as well.


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#13 · (Edited)
I would personally not use any wire product to clean a diesel cylinder deck. I have found 3M Bristle Discs work very well and give a polished surface with no scratches. I put a piece of foam tape in a circle, cut to fit inside the bore to seal the gap at the piston (I dont use the adhesive tape), and pack a rag in the cylinder above the piston, keeping it below the deck, and polish away with a 90 degree die grinder. High RPM and light pressure will give an exceptional finish. They also have the disc holder on Amazon. You will be amazed how the rubber fingers clean metal. There are videos about this on YouTube as well.


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I've read on other places that the roloc discs are great but some people say that they remove too much material. Not sure what to believe 🤔

I guess there might be multiple grades of the roloc discs which are more or less abrasive.


I think one issue is that 3M uses the "roloc" name for a lot of different products: https://www.3m.com/3M/en_US/p/?Ntt=roloc

Some of those probably are too abrasive. Others not so much...
 
#14 · (Edited)
There are a variety of Roloc discs. Its 3M' s line of abrasive discs that lock to the mandrel by twist or screw motion. The Bristle discs have a rubber like fingers, and dont shed abrasive material as they clean. They are gentle but very effective for cleaning the deck.
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#15 ·
Abrasives are still present in the 3M product. Less worry with draw filing (using a standard file 90° to normal motion) with towels stuffng the cylinders.
Yes, teeth of water the file can break off, abrasive products always shed grit. The file.just sheds dirt when it has already been used. And it shows high and low spots.
 
#17 ·
A brass wire wheel is fine, it just won't indicate any high spots like thread burrs, displaced metal from fire rings and burnished gasket fragments.

A flat file drawn over the surface after removing dowel rings is very fast, little pressure is needed plus high spots get knocked down. You don't need to get metal removal on the entire surface because you are knocking down high spots. Once the high spots are removed, the force bearing down on the file now is spread over much larger area.
 
#19 ·
The file will bulldoze any remaining gasket material. You will need to card (fine cleaning brush) or pick the teeth clean. I use a square cut piece of 1/8" aluminum plate clamped in a vise to clean the teeth. Rub on the edge of the aluminum in the direction of the teeth..works best on single cut files. What happens is a tooth profile comb is made in the aluminum, removing all swarf in the gullets of the file.

I've been doing a lot of filing of aluminum, hand and rotary. Use this method for both.
 
#21 ·
Mill Bastard, single cut flat. 12" will do it. Nicholson, think they are now hecho en Mexico now but seem to be equal. It's a century's old tool design.

No tool box is complete without one. Rinse it with light oil after use, keep wrapped in kraft paper to prevent knocking around with hard tools.
 
#22 ·
Cool, thanks for the recommendation. Do you have any videos of the proper technique with the file? There seem to be a ton of videos online showing how to use the roloc discs to clean up engine decks but I haven't seen one yet with a file.
 
#23 ·


If you apply force to the middle of the file, the surface will be flatter. By only holding the ends, the file had higher force on the edges so those were excessively filed.

Yes, files bend into a curve elastically. Very hard steel still bends, this is how springs work.

Otherwise, a good video. Trust your fingertips as you can feel defects 0.0005" high or deep.
 
#24 ·
Cool video. I got one of these this weekend: Nicholson 12 in. Bastard Cut Mill File 21842NN

Do you recommend using a second cut file like he suggests in that video after the first one?

One other concern I have is that it would be significantly harder to apply force evenly when the engine is in the truck. But maybe not as hard as I imagine given that it's very light pressure anyway.
 
#25 ·
Only light force is needed, the file is a high point detector more than resurfacing tool. It should easily skate over a clean surface. You don't need to bring the surface down to bare metal, just level to within 0.001" or less meaning you should not be able to feel any bumps.

When the file skates freely, some Permatex Gasket remover will remove any remaining Printoseal bands (colored compound on factory gaskets). Clean, level metal is what the new gaskets were designed to seal on, not polished.
 
#26 ·
Summer activities are taking up a lot of my time so I haven't been able to work on the truck in a few weeks unfortunately. Thankfully, I should have the next 2 weekends free.

Any tips on removing the dowel pins? I was just going to try some channellock pliers but figured I should ask if they have a special tool for it that's preferred. And do they need to go back in the same places?
 
#27 · (Edited)
Pull them with pliers. If you have a bolt/pin that just fits the inside diameter, this will prevent distortion while pulling. These are standard parts and should be available new for pennies. GM part number 3894327. New part is 12558081. $2.20 for a set of 4. OK, 54 pennies each.

Yes, there are specific bolt holes, you can't put them in the wrong one because of the counterbore required.
 
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