>From: Stephan Sochoux <sochoux@yahoo.com>
>Subject: Hot tanking vs Baking
>
>I called some shops to get quotes on getting the block
>cleaned and the first shop tells me they bake and do
>an acid dip, that hot tanking is not friendly for the
>environment and that it is "old". The second shop hot
>tanks and tells me that baking heats up the parts too
>much. Hmm.. either way produces clean parts but which
>is the preferred way ?
Hot Tanking is usually a nasty solvent bath... You
will need to replace the camshaft (R16) or jackshaft (U20)
bearings after an hot tank. Yep, environmently not a
nice thing. Lots of the shop have to pay $$$ to properly
dispose of the waste (full of metal/oil/carbon).
Bake and acid dip, also heats up the blocks (loosen the
grease),etc and usually the "dip" is more like a dish
washer. Lots less hazardous waste, and can be recycled
through the system.
Either way that are some things to be done:
Pull the oil galley plugs. My favorite way is to drill a 1/4"
hole through the front galley. Use a long rod through the hole
and knock out the rear galley plug. Flip rod around, and catch
the edge of the front plug and knock it out. Remove the freeze
plugs.
Deliver the block with the MAIN CAPS installed and galley plugs
knocked out.
Honing will be done AFTER hot tanking the block. Much easier
on the machine shop folks to handle a clean block.
When the block comes back...
I'll clean up a few of the casting marks under the engine with
my hand air grinder. Hey, this is really picky. I am looking
for any 'flashing' for the casting. Once in a great while you
will find a pocket of sand trapped in a casting. Super rare
on the old Datsun's... heck doesn't take must time. ;-)
I put it on an engine stand. I have my box of TSP (tri-sodium-
phasephate) powder, bucket of hot water, scrub brush, WD-40
bottle, garbage bag, and water nozzle ready to go.
Put on your heavy duty rubber gloves, face shield, Shop apron.
Yep, roll the engine out into the driveway. Scrub it down the
the TSP solution, and scrub brush. Do not forget to get down
lower on the engine and scrub everything. Lots of soap, suds,
hose everything. Keep going. Scrub them bores. Water squirting
everywhere.
With compressed air I will blow out all the passages. Also
use the WD-40 on the bores to prevent any rust from forming as
the block dries. Keep the WD-40 to just the bores/machined areas.
Oil galley brush through the main oil galley and every passage.
Run the thread chaser down through all the bolt holes. Dig all
that crud out of the bottom of the holes.
Chamfer the top off all the threaded holes. (Ok, ok, I am really
picky).
Nice dry clean block back into the garage. I will spray paint it
now. Cardboard tapped over the head gasket surface.
SUPER PICKY (i.e. race only). Paint the bottom inside of the block
with GLYPTAL. Used by motor shops to insulate windings. Stuff
stinks to high heaven. You need to do this in a well ventilated
garage (door open, fan blowing, warm day).
When you are done with all this... that block looks fantastic!
I usually install the freeze plugs before painting, other folks
like the install them after painting. Heck, your car do what you
like!
Don't forget to reinstall those main galley plugs, and that
freeze plug on the back of the engine (opps).
Cheers,
Tom Walter
Austin, Tx
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