At 08:19 AM 3/3/2006 -0600, Dave Williams wrote:
> My only experience with thermal cleaning was with a shop that destroyed a
>pair of antique Pontiac heads that way, then they tried to claim they had been
>cracked before they baked them. Since I'd just ported them, then paid them to
>Magnaflux the heads, I wasn't too receptive of that idea. I had taken the
>heads in to have a valve job done, and they were squeaky-clean already. They
>said they always baked valve job heads.
I would think that if a block or head could stand the normal thermal stresses
of operating, being
baked to a uniform temperature would be no big deal. Maybe these guys toss it
in a tub of water right after they take it out of the oven?
Anyway, I tried a larger-scale experiment: the flywheel housing of my '31 A.
This part goes
between the block and bell housing, and is a fairly thin casting. Mine was
quite gunky on
the outside with road crud, and on the inside with clutch and oil crud.
So (when my wife was out) I put it on the oven, turned on self-clean, and
waited. About
25 minutes later the (gas) oven started smoking heavily. The vent hood fan had
little effect,
and I to open windows and grab a couple of box fans to clear out the smoke.
At that point I turned the oven off, but I let it cool down with the door
closed. (Don't want it to crack!)
Smoke kept spewing out of the oven, and I was lucky all the smoke detectors in
the house did not go off.
When it finally cooled off, the crud was only half-baked since I had to abort
the mission early.
But it was not greasy any more: I could scrape most of the gunk off with a
putty knife and vacuum it up,
without getting the putty knife and vacuum cleaner all greasy.
The kitchen was rather smelly for a day or two, but it is OK now. When my wife
came home, she was amused as much as annoyed.
The bottom line: don't try this in your kitchen, but if you have something like
a powder-coating oven that you can let smoke without fear, it might be the most
practical way to clean big, slimy engine parts. Maybe you could use
a big barbecue grill, but the open flames might cause too much thermal stress.
Doug
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