Rusty block

paolo_mangusta · Post by **paolo_mangusta** » Thu May 12, 05 6:17 pm

Anyone had any experience of removing rust from blocks? The 360 block I have to replace my knackered one all looks good but has surface rust all over it, including the bearing faces. Obviously, it will need to be honed and have the cam bearings done, but can you sandblast a block? Anyone had any luck with chemical rust killers?

Blue · Post by **Blue** » Thu May 12, 05 6:46 pm

No No No! don't ever sandblast a block or heads! you will never get all of the shot out of it, until it all finds it's way around the oiling system and kills it totally. Best bet is to get it chemically de-rusted, it will come out almost looking new, it will kill the cam bearings, but hey you can't have it all ways! Any decent engine shop should be able to do it.

paolo_mangusta · Post by **paolo_mangusta** » Thu May 12, 05 6:52 pm

Cheers Blue - I'll try my local engine place to see if they can do this. I'll need to get cam bearings done anyway, so that's not a problem

Blue · Post by **Blue** » Thu May 12, 05 6:52 pm

Oh, and I've also been hearing recently that some engine builders leave new blocks outside to go rusty as this is somehow beneficial? Urban myth? or is there any truth in it? and if so why? I think we should be told....

paolo_mangusta · Post by **paolo_mangusta** » Thu May 12, 05 6:55 pm

yeah I heard this (and I've been telling myself that it's true to cheer me up!)

Apparently the BMW F1 team in the turbo era used to use Beemer 316 blocks that came from scrapyards, left them in the rain for a while, and even used to pee on them for luck.

Won't be doing that with mine, though...

Alex · Post by **Alex** » Thu May 12, 05 7:04 pm

Seasoning parts by leaving than outside has been done for years, Rolls Royce do it with cranks and many motorsport engine builders do the same. If it actually works is beyond me but them that know seem to think it is a good method.

Blue · Post by **Blue** » Thu May 12, 05 7:08 pm

Hmm, I'd like to know how that actually helps...

paolo_mangusta · Post by **paolo_mangusta** » Thu May 12, 05 7:16 pm

I'd like to know how they get the rust off

latil · Post by **latil** » Thu May 12, 05 9:49 pm

They don't de rust them! The idea is to take a fresh casting and lightly machine some key areas , maybe deck,bellhousing,sump area then weather the casting to relieve stresses. After a given time (often a full year) the casting would be taken back to the machine shop for all the final machining to it's finished sizes. Used to be standard practice on large railway engine (steam) parts , who could justify the lead time these days ?

Anonymous · Post by **Anonymous** » Thu May 12, 05 10:12 pm

Surely the best way to stress relieve an engine is to run it for a while, then rebuild it and get all the machining perfect on the rebuild?

Alex · Post by **Alex** » Thu May 12, 05 10:17 pm

Old blocks are sought after by racer because they have been heat cycled many times and the metallurgy has settled down, fresh blocks are still 'moving'

TrevD · Post by **TrevD** » Thu May 12, 05 10:21 pm

latil is correct , its all to do with stress rieleif , all metals are producd with a skin , if the skin is broken ( machined) it will release some of the stress , even a billet will suffer . at the moment a job im doilg is made from a 35mm thick stainless steel billet 400mm x 270mm , after removing 1mm from one face it bent 0.2mm ( 8 thou in english) . the same is true for a casing or a forgeing so if key areas are machined then its left the stress will come out and final machining will be more stable. this should also be true of a used block as the stress and temperatures a block is subjected to will affect its molecular structure so seasoning a used block before final machining will help reduce stress. but back to the queston in hand , get it acid diped , i had ICE do mine and my heads , loverly job but be sure to remove any bearings ( i forgot the oil pump drive bush

the acid eats them )

Dave-R · Post by **Dave-R** » Fri May 13, 05 8:42 am

You can't beat a block that has been seasoned with repeated use.

But you can also season a new block by heating it (to over 1200 degrees F if I remember right and I can't remember how long for?) and then cooling it slowly at a rate no greater than 200 degrees per hour down to 500 degrees and then it can just air cooled after that.

Not something you could do at home.

Kev · Post by **Kev** » Fri May 13, 05 8:50 am

Some of me Missus's cooking looks like it's been subjected to that, Dave!