Son of a b**** that didn't go well! Block hot tanked "cleaning"

[fairlaniac]

I was shocked when I picked up my 427 block from the machine shop. I asked for a hot tanking. Said I'd pick it up at 3:00 and he said on Wednesday he'd pull it out and clean and dry it off just before I got there. That came from a conversation that i was concerned about flash rust. Picked it up today and they said they had time so they did it yesterday. It sat for over 30 hours in the open door shop with Pennsylvania humidity around 92% and 88 degrees. Disappointed for sure. So what is the best way to go about cleaning the flash rust off? My bores were finished honed (pistons are on the bench) so I won't be using anything abrasive that could get in the bores. There is flash rust in the oil passages, rear seal groove and any little nook and cranny it could find. I should have just tried cleaning the block in the driveway :-( Thoughts?
Thanks!

[My3sonz]

Maybe an Oxalic Acid bath?   The 99% crystal powder not liquid. You need a (plastic) tub big enough for the block. It only takes a couple tablespoons diluted in water to work. Leave it in for 24 hrs and the rust turns yellowish. Wipe it off with a soft bristle brush or scrubbing sponge.  Not sure what it would do to cam bearings but it doesn’t hurt chrome or plastic.

[fairlaniac]

Maybe an Oxalic Acid bath?   The 99% crystal powder not liquid. You need a (plastic) tub big enough for the block. It only takes a couple tablespoons diluted in water to work. Leave it in for 24 hrs and the rust turns yellowish. Wipe it off with a soft bristle brush or scrubbing sponge.  Not sure what it would do to cam bearings but it doesn’t hurt chrome or plastic.

Cam bearings are out

[fekbmax]

WD 40 in a spray bottle and a green pad always works for me. Surprised your machine shop didn't spray and bag it.

[wayne]

Arm and hammer washing soda and a battery charger i think a fe will fit in 55 gal plastic drum.Hit and miss engine guys use this to free them up this is were i seen it done.Look it up on the web. It may clean your light rust over nite.

[Barry_R]

Looking at the back of that block it was never really cleaned properly the first time - before honing.  First effort now might be to take a dollar store toilet brush with the twisted wire shaft - cut off the handle end and chuck it into a cordless drill.  Douse everything with WD40 and buzz away at it for a while.  Then use little brushes and the previously mentioned scotchbrite pad to do what you can.

[fairlaniac]

I started with the WD-40 and a round nylon brush on a drill. Then WD-40 with Scotchbrite pads. It's all coming together. A little extra elbow grease than initially intended but it isn't bad at all. Thanks for the various tips.

[Leny Mason]

Hi Doug, I use ATF to clean my stuff I think it will take the surface rust off plus it coats everything nicely, Good luck The shop Sucks as far as I can tell, Leny Mason

[Red Lehr]

As Wayne mentioned, the Washing Soda and battery charger works wonders. I had a 427 block hot tanked a while back , but still gave the block the electrolysis treatment because the hot tanking doesn't get the rust off all the time. Sorry for your trouble Doug, it is aggravating for sure.
If you ever need a good recipe for setting up a tank to do the electrolysis let me know.
Red

[Falcon67]

Hi Doug, I use ATF to clean my stuff I think it will take the surface rust off plus it coats everything nicely, Good luck The shop Sucks as far as I can tell, Leny Mason

Same - works well. Sorry you had to pay for that kind of work.