Soda blasting engine case
 

I just pumped another hundred bucks into the Chinese economy and bought a Harbor Freight soda blaster and I'm getting ready to clean up my 3.2 engine case. I spent a couple hours degreasing yesterday and the case is ready for the next stage of cleaning. I've never used this method before and I'm curious how it will turn out. For those of you who have soda blasted a case, what can I learn from your experience? Should I avoid certain areas of the case? Plug oil passages, oil squirters, etc? I'll post some before and after pics when I'm done. Thanks!

the soda dissolves in water and the dirt it dislodges and mixes with does not. i don't feel good about blasting cases. cam towers too. too hard to be sure everything is out of the passages. YMMV.

I just bought a Harbor freight unit and find it to be magic on suspension parts and fasteners, etc.

My thought would be to blast the engine as a sealed long block before you take it apart. This will get off the hard outside stuff.

Hose it off, compressed air dry it, then take it apart and clean the inside and oil passages by removing plugs and doing the usual solvent based methods for these operations.

I would not be afraid to do individual parts like rockers, rods, piston crowns, etc. with soda blasting.

I did a full degrease on the case then soda blasted in and out. pressure wash off well then set to soak to make sure everything is dissolved. Another hosing with some bore brushes just to make sure it is clean inside and it will look like new. Degreasing gets the chunks and dirt out, The soda blasting removes the varnish and other discoloration well, and a good pressure wash after makes sure the dirt doesn't try and restick.

Soda blasting is great for many parts as it will not damage them. Just degrease first.

Also... wear a painters suit and a dust mask and goggles.

Although it likely wouldn't affect a cylinder wall, I'd avoid hitting it along with any other dimensionally critical surfaces. If you're working outside avoid any overspray to accumulate on cherished vegetation (eg. grass). I thought my wooded lot (i.e. acidic soil) would benefit from the alkalinic soda and it may have but not in the concentration created after shooting a 50lb bag.

I have to agree, it's just not worth the risk. It does not take much debris in the wrong place to ruin your day.

Today I decided to try soda blasting starting with the non-critical chain boxes:

http://forums.pelicanparts.com/uploa...1335501326.jpg

I was pretty happy with the results and decided to move on to the cam housings. There was some concern about clogging up the oil passages so I decided to plug them rather than worry about cleaning them out after the blasting process. I simply used electrical tape to cover each of the four cam journal oil holes and the pinholes in the spray bars:

http://forums.pelicanparts.com/uploa...1335504596.jpg

http://forums.pelicanparts.com/uploa...1335504724.jpg

Before blasting the parts were degreased with solvent. After blasting I soaked the parts in hot soapy water then rinsed thoroughly and blew all passages out with compressed air then cleaned with chemtool. The soda is a very benign media, dissolves easily in hot water and causes no damage to the aluminum. The mating surfaces of the cam housings cleaned up really nice with no worries about abrasion damage.

On the negative side I used way too much baking soda. I blew through a 50lb bag just doing these parts! It also gets all over everything but cleans up easily with a garden hose. So for occasional use with smaller parts, this system is ok. I wouldn't recommend it for large jobs. Obviously uncontained media blasting has its disadvantages.

Tomorrow I will take a careful look at the engine case and decide whether or not to blast it. If I can cover the oil squirters and plug the oil galleys adequately I may give it a try. I have decided that removing the galley plugs for cleaning is more than I want to do given that this engine didn't suffer any catastrophic failure with associated debris in the oil.

You're not actually using baking soda are you? Baking soda is good for baking pies! Theyre's actually a media called soda which is much more abbrasive than baking soda. I setup a tarp and collect the overspray and I'm able to use it at least twice before it turns into talc.

Well, I used baking soda from Costco. Worked great. Perhaps ignorance is bliss?

Soda blasting........
 

Are you doing this cleaning inside a blasting box (cabinet) or open air? I like to do similar project but working in my small blasting cabinet was quite awkward. Could you post a picture of your set-up? Thanks.

Tony

Hahaha! I'm using the soda media Harbor Freight sells that comes in a 50lb. bag for about $35. There is a large "Arm & Hammer" logo on the bag but I haven't tried baking with it yet!

Good idea about the tarp. That crossed my mind as I was cleaning up the mess...

I soda blast cam towers as well as many other parts using an Eastwood blasting cabinet and a pressure blast set up.

With the cam towers, I water flow the spray bars and cam journal oil supply afterwards to clear the oil passages, make sure they flow and flush all residual media .

I hung a 20' X 20' plastic tarp from a clothes line with half on the ground underneath a blasting cabinet made out of a large cardboard box from a fridge after trying to do it in a blasting cabinet. Position yourself upwind preferably on a calm day and cover yourself completely sealing any openings in your clothes with duct tape. The spent soda is very fine like talcum powder and gets into everything. Goggles and a good mask are a must. I was thinking of using a snorkel mask the next time attached to a hose for a fresh air supply, cause the mask filters clog up quickly. To collect the overspray,(i.e. most is caught in the box) lift one end of the tarp to collect overspray into a single pile and vacume up the clean soda for reuse. I use a $10 siphon type sand blaster which has a few different nozzels for different media and 3.5 hp compressor from Sears. The only issue I had is the siphon creates a crater in my bucket of media and looses its' prime, so I keep it within arms reach while blasting, so I can agitate the media to restore the siphon. If a pressure type sandblaster is used, one shouldn't have this problem.

Like Porshaah, I tried making a cardboard blasting cabinet with a clear poly cover. I found I couldn't see anything inside after a short while blasting (with a similar, very low buck, siphon gun). I went back to open air work, and hosed off the mess afterward. A real cabinet must use some kind of fan and filter to deal with this? But being able to reuse 50 or so % of the soda would be nice - I'll have to consider using a tarp next time I decide to do this. And maybe a cardboard box which is just open at the top? To help with the reuse part?

Cylinders, heads, cam towers, chain housings, and various covers are obvious candidates for use in a cabinet (though I just don't have garage space for one. The job this helped me most on was cleaning up a very gunky aluminum 915 case. Did a great job. Those and case halves would take a pretty large cabinet.

In my blast cabinet set up, I use a shop vac and sawdust centrifugal separator to evacuate the chamber and clear the dust.

Sorry I didn't provide more details on the makeshift cardboard blasting box but you figured it out by loosing the window. It 's just there to collect the immediate overspray and the tarp catches the remainder. When your blasting just aim towards the opening in the box and adjust the distance of the piece you're cleaning from within to outside the box to maximize what is collected by the box as opposed to what bounces back and into the air to be collected by the tarp. In fact one could probably just use a big tarp with the sides folded up. The idea I had was just to collect as much as possible for reuse and avoid killing the grass as I did the first time, by doing it in the open. I found the window on my real cabinet dusts up quickly with soda but is great for other media such as walnut shells and the fillter in the cabinet to the shop vac clogs up quickly too with very fine soda.

I thought te same thing after doing some blasting in the driveway.

Those towers look great. But I don't like messing with the rocker shaft bores or the cam bearing bores. Before I blasted the towers, i'd tape off the cam and rocker bores or stick some rubber stoppers in them

The spec'd clearance between shaft and bore in these locations is REALLY tight, especially the rocker shafts. Rocker shaft spec'd clearance is zero to .0001". That's freakin' TIGHT. Cams are 0.0009" to 0.0026" and wear limit is 0.0039" That's obviously a little looser because there's oil pressure in the cam bores.

You'd be surprised what crap can get in the spray bars. It's not a lot of work to pull the spray bars. The replacement plugs are cheap, or while you're at it you can tap the holes for 1/8" NPT and then have removable plugs for the next time you clean the housings.

Those spray bars are critical oilers and you have to be sure that nothing gets in there. Even though you plugged the pin holes, there are also holes inside the cam bearing bores that are exposed. Did you tape those shut? Not trying to be a jagoff here. Just trying to make sure you don't have a piece of FOD mess up all your hard work.

BTW my method to pull the cam bar plugs is to drill & tap for M5 threads and use a length of M5 all-thread and a nut & washer atop a small socket as a press fixture. Just be sure to use a strong screw material & oil the threads to keep the threads from being galled during the pulling. M6 is probably a better choice because you can get usually stronger screw material. But the M6 is very close to the size of the plug.

Also be careful to not drill too far when you go thru the plug. If you break thru and your momentum carries you to the next place the drill bottoms, you're hitting the spray bar itself. There's ample room between the end of the plug and the end of the spray bar. It's a decent sized cavity. So when you're nearing the end of the plug, go slow with no pressure on the drill. Then when you break thru, you don't jump down on the end of the spray bar.

KTL,

I've wanted to do this. Once you've got the plug out how difficult is it to get the spray bar out? Is the spray bar clocked at a certain angle for install? Is it the same end-for-end? What do use to plug the hole?

The spray bar just slides out once you have removed the plugs. It's orientation is set by the nipple on the plug at the far end of the cam tower.

Here's some good threads to look at:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/180548-spray-bar-orientation.html

http://forums.pelicanparts.com/911-engine-rebuilding-forum/254518-cam-spray-bar-plug-replacment.html

andy

Yep Andy is right on and picked the perfect topics to link. You want to make sure the spray bar is oriented so that the single pin holes are pointing out/up toward the valve covers and the double pin holes are pointing down into the cam housing.

The other check is to ensure you have the big holes in the spray bar (cam bearing oiling holes) aligned with ALL the cam bearing bore holes. Take a look at this picture.

http://forums.pelicanparts.com/uploa...1335841318.jpg

The cam oiling holes at the ends of the spraybar are indeed lined up with the threaded holes in the cam housing at the outer cam bearing bores where you have a threaded plug w/pilot pin at one end and the cam oil line supply fitting at the other end. But the inner spraybar cam bearing oiling holes ARE NOT lined up with the holes in the middle two cam bearing bores.

The key is to align the big oiling holes in the spray bar with the plugs on the exterior of the cam housing as pictured by Jim Williams in the second link

http://forums.pelicanparts.com/uploa...1197386546.jpg
http://forums.pelicanparts.com/uploa...1197386625.jpg

But Jim's statement that says "Note the holes in the tube, and the chain (correction- should say "cam") housing plugs. The plugs cover the hole which was drilled in the housing to get oil to the cam journals. If the spray bar holes are aligned with the housing plugs and the end hole in the bar is facing outward, there is only one way the bar will fit properly." is incorrect. You can have all of the large spraybar cam oiling holes properly aligned with the holes within the cam housing and still have the pin holes 180 degrees out of alignment. So remember the rule, one pinhole points up/out, two pinholes point down/in.

You can replace the plugs with the factory aluminum plugs. They are part number 901.105.379.00 Or you can tap the hole with a 1/8" NPT tap and install threaded plugs. Then the future janitor of the spraybars can remove them a lot easier!

I take back what I said here. The distance between the spraybar end plugs and the spraybar itself is very small. After looking at my towers again to respond to some questions, I would not recommend drilling all the way through the plug. Stop short of going thru the plug!

http://forums.pelicanparts.com/uploa...1335842167.jpg

http://forums.pelicanparts.com/uploa...1335842210.jpg



Lastly, you want to use the threaded fitting with the pilot pin to align the spraybars BEFORE you install the aluminum plugs. Doing so establishes the proper lateral location/depth of the spraybar in the housing. Then you can tap in the aluminum plugs. I suggest doing the pilot pin fitting install first, to avoid moving the spraybar when you're tapping in the aluminum plugs

thanks!

Ok it's been a while since I started this thread but I finally blasted the case. I was a bit turned off by the mess created by my first attempt at soda blasting my cam housings but I made a simple cardboard "blast cabinet" and added a tarp to collect the overflow which made cleanup very easy. I taped off the oil galleys with electrical tape to prevent the soda from contaminating the passages. The soda blasting easily cleaned the old sealant and gasket material from the mating surfaces and spigots where the cylinders mount up to the case. The soda is so gentle that it cleans easily without removing any aluminum material. When done, I washed the case halves with soapy water and rinsed thoroughly, then blew dry with compressed air. I also flushed the oil galleys and piston squirters several times with brake cleaner and compressed air. There has been some concern here about the soda clogging or contaminating the oil passages but, honestly, I don't see this as a problem with this method. Any residual soda is such a fine powder that it simply blows clear with a shot of compressed air and dissolves completely with water leaving the case completely clean and free of contaminants. Here's a few pics of the finished product. I'm very happy with the results and the case is now perfectly clean and ready for assembly.

http://forums.pelicanparts.com/uploa...1341990144.jpg

http://forums.pelicanparts.com/uploa...1341990228.jpg

http://forums.pelicanparts.com/uploa...1341990303.jpg

http://forums.pelicanparts.com/uploa...1341990382.jpg

http://forums.pelicanparts.com/uploa...1341990441.jpg

The concern with soda is if it mixes with residual oil, it can create a sludge that will not easily rinse. It is important to make sure all oil passages have been thoroughly cleaned before soda blasting.

I am getting into this string long after everyone has moved on... Oh well.

I have been grit blasting Porsches and their parts since the 1960s. I used to just wear a mask etc. For about 30 years, I have been using a mattress bag. This is way better. I poke a hole for each of my hands in the 2 corners opposite to the end which was cut to remove the OEM product. The bags I use are about 6 mil thick polyethylene. With delicate work, I use bare hands. I use heavy rubber gloves on my hands, then pushed through the holes, for heavy blasting. If you do not like the transparency of the poly, you can cut a 3 by 6" hole, and tape over a window made from a piece of clear shelf-pack PVC. The view through the poly is not bad in bright sunshine. In this way, you breathe the air you trapped in the bag before you started making dust. No sand drops out off your eyebrows a day later into your eyes.

I like to blast on nearly windless days. A few MPH is good, as it clears the dust. I walk a few yards away before taking off my 'hood'. I use tarp curtains to keep the dust and grit from getting too far away. I sweep up and re-use. When the grit turns to 10 micron dust, it blows away.

I used to blast small parts like Zenith carb housings with very fine glass beads. Of course you need to plug openings or remove OEM plugs.

I sandblast whole engines, after removing the flywheel, greasiness, shroud, exhaust and intake. A rubber lab stopper goes in each intake and exh port. Rags and duct tape and duct seal putty keep sand out as needed. It removes grime and oxidation, and little gets inside. This is all written up in earlier issues of my RED RIVER SPORTS CAR ENTHUSIAST newsletter.