Folks who have had a block hot tanked...

I would definately take the block back and show them the poor job they did.You paid them to clean it,and it sounds like they did not do a good enough job.Maybe it is not worth the trouble,and you should find a more professional machine shop to deal with!

I had a 351 Ford block hot tanked once and there was a tramendous amount of crud left in the oil passages that feed the lifters. Had to spend several hours cleaning that out by hand, so it won't clean every nook and cranny. The rest of the block was OK. You might call the people before taking it back to the shop. Might save you a trip if they don't think a second cleaning will help.

Hot tanks need to be maintained with periodic additions of acid to retain their effectiveness, sounds like the one you sent your block to was needing a recharge.

The shop I use when I get it back its ready to assemble thats what we pay for.I agree tank most likely needed recharged.

Mine (400SB) came back with a little crud, nothing I was not able to clean up in about 2 hours.

Well guys, I haven't decided whether I am going to ask them to do it again...I do know I probably will take future business elsewhere. It took way too long to get it back for it to not have been clean. I do realize the block still has to be washed, but this thing still has black oil gunk above the cam bore.

I think I'll probably take it to another shop and have it tanked AND fluxed again

Thanks to all who replied

hot tanking is old hat, today there is sonic cleaning which does a much better job and if your machine shop is still hot tanking probably the rest of the equiptment is old also. the machine shop I use sonic cleans all engine blocks and when it comes home it's clean,eat off it clean