Bead or Vapour blasting and oil galleries.

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bsaboss

bsaboss

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I was dropping some frame brackets in to have them sandblasted and the blaster had a set of cases from a four cylinder Japanese bike sitting there, waiting to be bead blasted. I asked him whether the owner had blocked off the oil galleries and got a blank look. On the one occasion I had a set of cases vapour bead blasted I made up various blanking plates to prevent any beads getting into the oil galleries. I did so on advice from a mechanic mate who ran a Jaguar repair business. He'd had a nasty experience with a vapour blasted head that managed to retain enough beads in oil gallery dead ends etc to total a fully rebuilt Jaguar engine (not a cheap fix!). What do others do? For example, do you blank off the rocker shafts when you bead blast a head? Perhaps I'm being overly cautious and a high pressure wash works well enough to shift any beads?
 
I had a Honda CB 750 head done with Crushed walnut shells....they'll burn up if any get left behind. Sorry but no experience with other methods.
 
Soda blasting?

Perhaps any form of blasting is problematic as its not just the media used, but the debris liberated in the process that can get stuck in places. Ive heard it is nearly impossible to prevent entry into all passages no matter what is done to block them off.
 
No matter how you clean it you will have to attend carefully to every passage and nook and cranny. Even if you didn't vapour blast you still have to get out accumulated silt. Endless flushing whilst you probe is the only way. Blasting with compressed air as well. Not all of us have a good parts cleaner so we have to go the hobby shop route.
 
Ultrasonic cleaning does just as good a job and will clean out any galleries as it goes, soda blasting is also good as water will dissolve any grains left in a gallery. If you want to block off a gallery prior to blasting Blu tac is very good.
 
I've been blast cleaning engine & other parts for forty years & never had a problem. The secret is to COMPLETELY clean out all the oil ways & screw threads before blasting & remove any oil gallery blanking plugs where ever possible. The next step is to spend several hours blowing & then washing out the parts with solvents. Until I retired from engineering I had access to Trichloroethane vapour tanks which were very effective at degreasing parts. When I send a Triumph P39 (OIF) type frame to be blasted/powder coated I spend a lot of time cleaning out the oil with petrol, then jet washing. When it's completely clean & dry I fit blanking plugs & plates. Once back from the powder coaters I spend another hour or so cleaning it out again, as some of these frames are not fully welded around the headstock gusset plates & grit can find it's way in to the tiniest of gaps.
Basically if you want to avoid problems you need to put the time in & be patient.

Martyn.
 
Blasting certainly carries risks of subsequent engine damage unless you're either careful to block off all galleries beforehand or scrupulous in your post blasting clean. I hadn't thought of ultrasonic cleaning as an option for large items like cases and heads, but I'll see if anyone does it commercially in my area.
 
I agree with bsaboss, nice post.

I favor tumbling in spherical, ceramic media as the process tends to gently peen the parts making them, arguably, slightly stronger and less likely to leak. This process as with other media blasting can also enlarge bearing bores; if they were on the edge of offering an adequate interference fit media blasting/tumbling may remove the interference, not good.

Having paid a few "tuition" bills learning this I leave the old bearings in place and cap the oil passages prior to tumbling. When I get the parts back I make sure that the oil galleries are flushed and clear. I put a rubber hose over the intermediate timing gear shaft secured with a hose clamp. There are a number of other considerations, I'm sure you get my drift, please feel free to add to this.

Best.
 
I worked in an aircraft generator repair shop and we had a glass bead blaster and a large (30 gal) ultrasonic cleaner. I'd bead blast engine parts and put them in the ultrasonic cleaner, did the trick. Unfortunately the shop is long since gone.

When I stripped the frame on my OIF Triumph I created a "reflow" system where I circulated kerosene through the frame. I used a venturi nozzle to spray the kerosene into the filler hole and drained the kerosene into a gallon can which also acted as my supply tank, I ran it until the inline filter showed no residue and grit. I used kerosene because it was inexpensive and left a slightly oily residue which helped prevent corrosion. I also did frequent oil changes for the 1st 1000 miles.

I've been doing soda blasting recently with a hot water (dishwasher) rinse and compressed air dry off.
 
Let me provide some light on this subject. We provide Vapor Blasting services for our own builds and other shop service work including carb cleaning. We also provide Vapor Blasting services to other shops and have engine case, carbs and other parts shipped from various parts of the U.S.

To answer some of the questions posed here, Vapor blasting can be used for every part(even rubber), no matter the size of the passageway or chamber.

I will use an Amal 900 as an example because the pilot jet bushing is so small. We have processed dozens of these Carbs without any issues or “blockage” because no matter how you clean them(glass, sand, ceramic beads, etc.), you must take proper steps to ensure everything is clear immediately after they are processed.

For carbs that are heavily oxidized, a harder media is used, and we block the small passages with rubber plugs as this media will be more aggressive.

Once that is completed, the carb is ultrasonically cleaned, and then we process it (with all passageways open) with a super fine media along with a liquid polish that brings back the better than factory finish.

It then goes back into an ultrasonic bath, passageways checked, then air-dried and reassembled.

While this sounds like a lot of work, a set of cabs in horrible condition usually takes about one hour to complete.

As for gasket surfaces and brass bushing etc., you can vapor blast using a super fine media with no change in the surface other than a gentle cleaning. Again the theme here is more aggressive the more issues you will have.


Regarding ultrasonic cleaning, we have a few tanks we use, including one that fits engine cases. Using the Amal example again, we have seen times where this type of cleaning has been done and freed additional debris, leading to blocking the bushing simply because they left the carb to dry and didn’t immediately ensure the passages are clear.

The big issue with ultrasonic cleaning is what people use in their machines. We have seen aluminum parts destroyed by the “green” Simple Green” because it wasn’t appropriately diluted or even because the water they use had the wrong kind of minerals.

It’s a trial and error process, and you don’t need whatever voodoo cleaner is being sold for these machines. Many times the heat and vibration are enough just using a mild soap.

Sorry for the long post, but I hope it was informative.


You can see some of our work here https://www.citygaragemotorcycle.com/vapor-blasting
 
Bunnings brass bristle brush.

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Close to 70 years old.

Bead or Vapour blasting and oil galleries.


Hey presto.

Bead or Vapour blasting and oil galleries.
 
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Ultrasonic cleaning with a weak citric acid solution.

1/2 submerged to show before and after

Bead or Vapour blasting and oil galleries.


and a fully submerged brakeplate after assembly into wheel and polishing of the outer flange.

Bead or Vapour blasting and oil galleries.
 
cjandme said:
I had a Honda CB 750 head done with Crushed walnut shells....they'll burn up if any get left behind. Sorry but no experience with other methods.
Click to expand...
Crushed walnut shells are primarily cellulose. They are to soft to do any harm, other than that they might plug up an oil passageway.

Walnut shell blasting

Cellulose

Back in the 1960s, VW had problems with engine repairs where glass bead blasting was done to clean cylinder heads and crankcases. Rapid engine failure often occurred when this process was used. They found that the glass beads would embed themselves into the aluminum. When the reassembled engine would reach operating temperature, the pores of the aluminum would expand, open and release the embedded glass. The glass would be carried by the oil all over the engine, doing severe damage.
They banned the use of glass beads, stating to use only crushed walnut shells as a blasting media. I have no experience with vapor blasting, so I don't know how it differs from dry blasting, other that it uses a water/glass bead mixture.
 
Like many things, I do cases and heads differently from others
1) Remove all bearings, valves, open all passages, leave all bushings
2) Clean with WD40 and a brass brush
3) Clean with hot water and something like Simple Green being sure to flush out all passages and threaded holes very throughly.
4) Blast with Glass Abrasive #75 just enough to get the metal clean - it will look weird.
5) Scrub very well with hotwater, soap, and a brass brush.
6) Blow out all passages and threaded holes
7) Scrub very well with hotwater, soap, and a brass brush again.
8) Blow dry
9) Thoroughly remove all Glass Abrasive from the cabinet
10) Put a small amount of NEW glass beads #7 in the cabinet
11) Turn the pressure down to 45psi (very important)
12) Blast the cases at an angle all over. This step takes less the 10 minutes and they will look new.
13) Scrub very well with hotwater, soap and pay particular attention to the oil ways and threaded holes.
14) Check every threaded hole - if there is ANY grit in any hole, go back to 13

Lots of steps but doesn't take very long. If afraid of my way, both cNw and Jim Comstock do the tumble method and they come out looking the same as mine. If you're not patient or through please don't do it my way - pay one of them to do it! I had Jim fix the exhaust ports in a 850 head and tumble it too - very happy with the results. I had Matt install his reed valve upgrade in a set of cases and had him tumble them while at it, again very happy with the result.
 
In the UK I've used an outfit in London called "I Cleanz Machinz" to vapour blast some triumph crankcases. Whilst they didn't guarantee there was no media left in oilways etc, they also stated they'd never had any comebacks after ultrasonic cleaning very carefully afterwards. They use a variety of media much as described by City Garage above. The place was full of semi priceless Ferrari, Aston Martin and the like vintage cylinder heads, every time I went there.
Whilst I do the mild acid /brass brush /soda blasting at home, the vapour blasting leaves a beautiful finish that closes the pores and shrugs off stains. My bonneville still looks great 10 years later!
 
Degrease, wash, rinse, media blast, rinse, hole brushes, rinse, pressure washer, compressed air, pressure washer, compressed air.

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Only this clean twice in 50 years.
 
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wavey_davey said:
In the UK I've used an outfit in London called "I Cleanz Machinz" to vapour blast some triumph crankcases. Whilst they didn't guarantee there was no media left in oilways etc, they also stated they'd never had any comebacks after ultrasonic cleaning very carefully afterwards. They use a variety of media much as described by City Garage above. The place was full of semi priceless Ferrari, Aston Martin and the like vintage cylinder heads, every time I went there.
Whilst I do the mild acid /brass brush /soda blasting at home, the vapour blasting leaves a beautiful finish that closes the pores and shrugs off stains. My bonneville still looks great 10 years later!
Click to expand...
So you dont need to treat or paint them afterwards? That sounds just great! Do you know what they used in their ultrasonic cleaner?
 
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