Hello,

I recently sandblasted my crankcases and the service guy did not properly clean them post blasting. Now it looks like the pump holes have a lot of fine sand. Luckily I haven’t fixed the pump and the cylinder but fixed both the crankcases together. Is it advisable to do a high pressure water wash through the holes or should I go ahead and take the covers off to give it a wash? Will water in the cases have any effect to the crank?

Tavery

email (option): tavery.p@gmail.com

I clean mine by an initial blow through with an air line followed by a thorough wash in hot soapy water and then a good flush with a jet nozzle on my hose pipe and a final blast with the air line again......I don't see how you can do this properly with assembled crank cases. Ron

email (option): ronpier@talk21.com

Blasting any engine parts is fraught with problems and danger.

It is worth blanking off any oil ways - even to the extent of screwing self-tapers and threading them internally for a screws.
Or knocking in wooden pegs which can be drilled out later.
BEFORE YOU GIVE YOUR C/CASES TO THE BLASTING COMPANY!

Anything to prevent the blast medium going where it should not!

Sand/grit is the worst and as it gives such a poor finish on aluminum (attracting marks like a magnet)i would have used AquaBlast (glass beads) or similar - which can give a semi burnished finish.

The best of all is Frozen CO2 blasting - commonly used to remove the gel-coat from boat hulls (to get rid of Osmosis) this gives a really nice smooth finish AND as the blast medium melts to a liquid/gas afterwards, does not have the grit in oilway problem.
Not a common process but if you are near a yacht harbor/marina it can be a real option.

Once blasted with grit - you need to use a strong cleaner/degreaser + a bottle brush, to get any s**t out - as you can imagine its highly destructive.

Someone who worked for me had a complete Honda 400/4 engine blasted - he meticulously blanked off everything to prevent grit ingress, knowing the problem - he refused to strip the engine after blasting ........
It lasted about 5-600 miles before the cams and head went - and thats with an oil filter.
I think its still at the back of his garage - another dream gone ........

This reminds me of the guy I knew who complained that the stove enameller did not remove the swinging arm before he painted it; it took a lot to convince him that it was no job of the stove enameller to dismantle his bike.

It's down to you to clean degrease any part thoughly before it gets near the sandblast guy, same as its down to you to clean it afterwards.

You are doing the guy a dis-service by slagging him off for your own fault.

But above all, as has been said, it should never have been sandblasted in the first place, I'm wondering if you also got the oil tank blasted at the same time?

I dont think its a good idea to blast anything at all, centainly not engine parts.
Just clean them as they are.
Besides, after blasting they get dirty very soon, so there is no point in doing so.

This all rather depends on what service was offered by the blaster...blasting is just blasting but he should be co-operating with the masking of any sensitive surfaces.

There are contractors who provide a full service and this will usually include the ultrasonic cleaning of any castings afterwards.

Personally, if I had an engine with any sand in the castings, I'd give it a couple of hours in an ultrasonic tank, turning regularly. I'm quite fortunate to have a 60 litre tank at work.

Sand blasting does leave a very dry, porous surface but vapour bead blasting leaves a sealed smooth surface that, with care will remain good for years.

I've been building engines and gearboxes for my own use for over 40 years and also did it for other people for nearly 20 years..

ALL of those engines/boxes had the major castings bead blasted and also many had the internal components blasted as well to ensure absolute cleanliness...

No engine I have rebuilt has ever failed due to the effects of the blasting process and it is purely a matter of spending the time to thoroughly clean the parts to avoid any potential problems...

It's not rocket science...Ian

email (option): ian@wright52.plus.com

yebbut....I bet the castings you sent where clean and dry beforehand? not full of clag, oil and grease to trap the blasting medium.

They were, as I prepared all the castings before blasting them in my own cabinet...

Bead blasting has been around for a long time and the methods of preparation and process are well defined...

I'm just pointing out it is a total fallacy to suggest there is some reason it cannot be used on engine castings...
The proviso, of course, is that the time is taken to investigate the correct method before proceeding and to follow it...

What hope of success is there with anything if you don't follow the basic rules....?...Ian

email (option): ian@wright52.plus.com

"I'm just pointing out it is a total fallacy to suggest there is some reason it cannot be used on engine castings...
The proviso, of course, is that the time is taken to investigate the correct method before proceeding and to follow it..."

Exactly my point.
or you could just hand over a big greasy muddy lump............

so many would be restorers have no idea of the processes involved in things like enamelling, plating or cleaning processes.

I have seen people take a complete wheel into a chrome plater and ask for the rim to be plated; I have seen unwashed oil tanks in the shot blast, as well as complete wheels bearings and all,and frame with half a set of forks still on it.

I knew a fool who put his T120 head into bucket of caustic for a week.... its endless.

Beadblasting is OK for crankcases etc but never never sandblasting. Its horrible to go round an autojumble and see all the ruined parts that some idiot has thought he has "improved"

You don't need a sandblaster to butcher an engine .
I can blast, and soda blast and ultrasonic clean.
I also boil.

Also I can sand blast with a variety of paticle sizes , air pressures, air velosities and that is before I decide which "sand" I want to use.

email (option): bsansw1@tpg.com.au

This has caught my attention as I have a number of gears and internal parts that need de-rusting, I was thinking of acid dipping them or getting them vapour blasted, but as some parts are presumably hardened will either of these processes damage the hardening?

I Built my own blasting cabinet from an old plastic barrel, its just enough to fit a 19" rim in there.
The blasting material was the most expensive thing on the build, and second to that the thingy to control pressure (20 €).

Never have gotten the hang of posting pictures on this forum but maybe some link here will work
https://www.flickr.com/photos/bohuslan/8271022616/in/album-72157629556474519/

%%bbCodeItem_1%%DSC02247 by Bohuslän i mitt hjärta, on Flickr

This picture was taken before the "gloves" where fitted.

And I always clean the parts before going in, and after taking them out.

/s

email (option): horror@blueyonder.co.uk

As Horror says if the gears are badly pitted they probably won't benefit from any kind of treatment...(other than a walk to the scrap bin)

If there is just light surface corrosion and no pitting, bead blasting with an aluminium oxide grit of about 60 grade will bring them up very nicely...

Some of the components in the picture with my previous post were cleaned using this method..

It won't affect them dimensionally and will have no effect on any heat treatment process carried out during manufacture...

I think it would be wise at this point to note that sand blasting, using sand, chilled iron or other coarse media is a wholly different process to bead blasting using aluminium oxide bead, glass bead etc. etc..

These compounds can be selected in grades that have no effect on components dimensionally and will not mark the surface finish or damage it in any way...
There is no need for example, to mask off threads or gasket faces on aluminium components..

All it does is clean the component..

When I worked at British Aerospace we had a blast cabinet set up to clean plastic components and even these weren't damaged by the process...(If I recall correctly it was crushed walnut shells that were used as blasting media)
..Ian

email (option): ian@wright52.plus.com

I use sand for rough and rusty steel parts, and sometimes for cast iron, mostly I try and use a pressure no higher than 4 kg (sorry for speaking metric), sometimes up to 5 but never higher because then the sand turns to dust.

For all alu-parts such as cases, timing covers and more I use soda glass (correct word in english?). I bought some very expensive material that can take over 6 kg pressure and that due to its fine nature it never damages the material, just leaves a smooth and clean surface. Mostly I use about 5 kg for the soda glass.
I have it separated so that half it is used on alu only. Reason for this is that if you use it on steel and then on alu you risk of shooting tiny bits of steel into the metal, and then you may get tiny spots or rust. Not good looking on your crank cases!

I started getting into this while restoring my Vespa (1966 180 Supersport) and found that it was quite possible to get real good results, without to much of an investment if I built my own cabinet (already had the compressor though). And as a bonus I have full control of the process (e.g. the no-steel use mentioned above).
But then I have no one to blame for the "Poor Quality Workmanship" when things go bad...

/s

That's a nice barn you Vikings got there.

And i thougt you were building a rocket !

I can think of at least one 'stove-enameler' round here who won't even clean grease out of the steering head - so when its heated it up, molten grease screws up an otherwise acceptable finish!
Then blames the customer .............. at least the guys i use tell me to go away and clean things out properly - or else they charge extra!

I guess its difficult for someone who does the odd restore - people like Ian/Ron and to a degree myself have been doing this stuff for years, and develop a network of specialist 'sub-contractors'.
I set up my own blasting cabinet etc, but like spray painting - the resulting dead-spray, dust, space, wasn't worth it.

I guess the answer is to clean VERY THOROUGHLY what you have and to use a specialist 'finisher' in the future - there are many small outfits around the UK who can properly aqua/soda/fine-grit/etc blast parts for you.

People tend to underestimate things like the amount of grease that can end up in a headstock.

On one of my bikes I warmed up the headstock with a blow lamp, just to get the grease out, what followed was a very long sausage of greases looped out from down inside the frame tubes.