cleaning the top of the block for new head gasket???

[towns]

I am about to put my freshly redone head back on my 1.6 TD   , and am wondering how 'spotless' the surface of the block should be?  I scraped off what i could with a plastic scraper and wiped it down with degreaser, but I can still see a few spots where there is a very fine layer of the old head gasket, for example at the back of the block, there is still a blue line from the old gasket and a few other spots.  Do i need to remove this?  The bentley says not to sand the block, so I dont know what else I can do other than what I have already done

[935racer]

I just get a razor blade and scrape the the deck down so its just bare metal everywhere. Never had a problem.h

[jtanguay]

just try not to put any gouges on the surface

[fspGTD]

Razor blade works well and is what I've used in the past before I got a die grinder setup, but it does leave some junk behind as it can only skim across the top "peaks" of the cast iron surface.

You can do better if you have a die grinder.  I found those scotchbrite rotary pads used on the ends of die grinders work amazingly well for removing all old gasket material but leaving the metal unmolested.  They come in 3 different grits: ultra fine, fine and medium.  I think fine or medium would be appropriate for cast iron block surface with light pressure.  Ultra fine with light pressure would be appropriate for aluminum head surface.  They will blow junk around though.  This link should be useful: http://www.sa-motorsports.com/blockdiy/blkdiy.shtm

[Black Smokin' Diesel]

Razor blade works well and is what I've used in the past before I got a die grinder setup, but it does leave some junk behind as it can only skim across the top "peaks" of the cast iron surface.

You can do better if you have a die grinder.  I found those scotchbrite rotary pads used on the ends of die grinders work amazingly well for removing all old gasket material but leaving the metal unmolested.  They come in 3 different grits: ultra fine, fine and medium.  I think fine or medium would be appropriate for cast iron block surface with light pressure.  Ultra fine with light pressure would be appropriate for aluminum head surface.  They will blow junk around though.  This link should be useful: http://www.sa-motorsports.com/blockdiy/blkdiy.shtm

JOO ARE MY HEROO!!! Thanks for the link!!!  :lol:  :lol:

They have a nice P&P guide too!

[vwmike]

I find a sanding block with fine paper works really well too.

[Master ACiD]

i have a rig made just for this purpose. it consists of a 12 inch by 12 inch piece of flat glass that is 3/4 inch thick. i use 3m contact adhesive to glue a sheet of wet-dry 200 grit metallic sand paper to the glass.

it takes a little bit to do a block because its cast iron, but once i am done the block surface is super clean and the process of flat sanding with glass lets me know if there are any high or low spots on the block (there never is).

i also use this setup for cylinder heads. while this process wont fix a warped head, it will flatten out and high or low spots and gives the sealing surface an incredibly smooth look.

[935racer]

I would highly reccomend NOT using a die grinder to clean the deck of your block, you will get a lot of crap going into your oil and coolant gallies, but the worst thing is that you will give the deck a slightly uneven surface. If you wanted to do the sanding route use a palm sander, something with a flat surface. Razor blade is my favorite cuase you can avoid dumping crap in your gallies.

[tylernt]

I just used a bronze brush and some carb cleaner. Seemed to work okay. The block was pretty easy compared to the head.

[Master ACiD]

to avoid getting stuff in the oil ports, water jacket, cylinder, etc, i use compressible ear plugs, masking tape, news paper and tyhose little packing noodles made out of styrofoam to fill in the aformentioned areas before i do any sanding.

[chrissev]

I am about to put my freshly redone head back on my 1.6 TD   , and am wondering how 'spotless' the surface of the block should be?  I scraped off what i could with a plastic scraper and wiped it down with degreaser, but I can still see a few spots where there is a very fine layer of the old head gasket, for example at the back of the block, there is still a blue line from the old gasket and a few other spots.  Do i need to remove this?  The bentley says not to sand the block, so I dont know what else I can do other than what I have already done

the block surface has to be spotless.  What I did was I bought a brass window scraper (at Canadian Tire) and scraped it with that.  Brass apparently is lighter metal than iron so it won't scratch the surface.  You can get away with a lot of scraping on the cast iron block but be very careful with the aluminum cylinder head.  Aluminum is very soft metal and if you scratch it, the new gasket won't seal properly.

[dieselweasel]

I always use sandpaper for cleaning blocks...usually 120 grit.  You don't have to have a shiny surface or anything...just need to remove all gasket material and any rust or carbon.

[watsongs]

I just did that today - 400 grit wet/dry wrapped around a hardwood block, w/WD-40 as the sanding lube.  Worked pretty well.