How to clean headgasket sealing surfaces?

[HAVABEER]

straighten the block...

bah isn't that why we have the gasket? to take up any unevenness in the mating surfaces, and why we have high tensile head bolts so you can really reaf the distortion down flat




*please dont take the above sentence serious*

[andrew_mx83]

In an ideal world, with perfect prep on both surfaces you shouldnt even need a gasket... do the job properly with good prep and the gasket is just there as a backup

[Hatta1978]

Hi, Ive done a few head gasket cleaning myself. I think the best way to clean it off is to use a new cutting knife.(the one normally used for general cutting). If its sharp, it should remove the residue and carbon clean and easy. Please remember to seal off the piston bore, oil passage and water jacket to reduce the chance dust from entering those holes during scraping. Maybe some elbow grease is required too.

[wasfishing]

so is it alright to use scotchbright on the head? or will it scratch it to much?

[allencr]

No, it won't scratch too much.
It needs a clean smooth bright metal surface on the block & head for theHG's narrow fire-ring to seat on, everyplace else almost irrelevant, with no scrapes scratches nicks gouges or corrosion pits on it. Stuff you can see but not feel, except just barely with your fingernail.
It doesn't need straightening/machining unless it's out more then 1/2 of the factory spec of .05mm/.002in if using a thin single or multi metal gasket. No burrs or raised threads around the bolt holes.

Keeping abrasives out of the rings & lands is the hardest part, carbon is next, so some grease around the bore to trap it & only move the piston down so it isn't forced into the rings. Resist the anal urge to clean combustion chamber, piston top & the cylinder ridge's carbon buildup, it does more harm then good. Just bust off the loose stuff, that's all, it'll save time, raise the comp.ratio & lessen the chance of it getting where it shouldn't.
Plug the oil gallery, blow out the bolt holes. Scrape the coolant passages if you want the radiator tubes to catch it & clog up.

[2004lowlux]

i just used gasket stripper pallet knifed it off after about an hour comes up ok then polish with a soft scotch pad like the one you get for die grinders on a drill it came up a treat and sealed ok no problems

[MorGo]

Having a clean deck is something different to STRAIGHT deck!
Don't fool yourself with Scohtsbrited surface;it can be clean and bright but WARPED!
All the blocks I do goes to the grinder.Some need only 0,15 mm skim;some need 0,5 mm.
Stock Toyota head gasket is 1,25 mm thick and compress about 1,1 mm when torqued down.If the deck is warped 0,3 mm what chance the gasket have?
Not to mention new metal gaskets..

But you do as you like;I do as is best.

[Rodger]

Hmm. MorGo you have a point. There is a difference.

Having a straight/flat deck is important. Having both a straight deck and a clean one is ideal, agreed.

However wasfishing really needs to weigh up pulling the engine out of the car and pulling it down to have the block skimmed for a correction of a head issue, or cleaning and adding a new gasket and bolting on the head. 60km hmm!

I'd clean the block surface and put the head back on. allencr is on the money about using grease and I'd forgot about cleaning the bolt holes out. I too do not clean the combustion dust off the pistons or chambers. Any loose bigger stuff goes though.

I have recently changed the cam in my 2T, in car, adding new lifters and some rocker collars whilst apart. I cleaned both head and block as I have described and put on a Cometic metal head gasket. No signs of oil or water leaks or compression loss after 600km. This recent work being done after a rebuild at 4000km of competition use, a head skim and valve reseat and my ancient cam/dizzy mash up issues

Regards