How to leak check aluminum head?

[Gary_Ash]

I'm getting ready to have a 1937 Studebaker President 250 cubic inch straight 8 engine rebuilt.  It's a flathead, valves in block.  I have the cast iron head that came on the engine and also a nice-looking aluminum head that I would like to use as it has higher compression.  It seems like a good idea to leak check the head for cracks and internal corrosion holes before I have the engine shop bolt it on.  Besides a dye penetrant test on the visible surfaces, what other methods of testing can be used?  It would be nice to pressure test it, but there are so many holes for studs and cooling passages that it seems I'd have to make a heavy steel blank-off plate to do that.

 

Also, I'd like to polish the aluminum head.  What types of buffing wheels and grit do I use?

[edinmass]

Cislak has a block off plate for the big Stude motors.........you will have to make one..........lots of those pre war heads are bad...........I haven't seen too many original good ones.........maybe one or two. Its worth the effort to pressure test it BEFORE you polish it. Frank Casey has a bunch of stuff to pressure check that thing, and he is close by. If it were me I would probably just shot blast it. The car will be fast enough.......you don't need the dazzle.......unless you want it. With the trick header and four carbs the bright head will distract from the engine.....in my humble opinion! Car looks good in all your posts.......Ed

[auburnseeker]

With polishing you will want to start with 220 grit or coarser.  You have to smooth down all the roughness before you polish.  I have used as coarse as 80 grit for particularly rough castings and even a rasp for something I was somewhat sculpting.  On flat surfaces it's good to somewhat block your sanding when in the coarsest grits so you don't make a bunch of waves in the aluminum.  Remember every scratch with the coarsest grit you put in it,  you have to take out with the next grit.  The Roloc wheels guys use for cleaning gasket surfaces work well as well. You will eventually probably go 320 or 400, then 600 then 1000 then 1500,  before polishing with a buffer and white rouge compound.  Alot will have to be hand polished because of all the nooks and crannies so a dremmel tool will be handy. If you have to truly hand polish it without a tool,  you may even want to go 2000 grit in those areas.  Cross sanding in opposite directions with each grit will show you if you got all the coarser scratches out.  I have been able to go from 1000 to machine buff on a big buffing wheel depending on how soft the aluminum is. 

Good luck but definitely worth testing it first as you will have alot of time in polishing it.  My favorite Aluminum hand polish is Mother's in the little round can available at probably every parts store and Walmart. The big can will last you for years. 

[Mark Shaw]

You might try bolting the two heads together with a piece of sheet steel & gaskets on both sides.

[Gary_Ash]

Mark:  I like that idea!

[Graham Man]

I like to glass bead blast the aluminum first, then use aluminum wheel cleaner, last step is put a good quality high temp engine clear on the head.  Leaves a nice looking finish.

[Curti]

Some of the guys try polishing the aluminum heads on Auburns.  In my opinion they never look finished. It is like a paint job with orange-peel. 

[DavidAU]

Take it to a Cylinder Head repair shop.

Those places weld up cracked aluminium cylinder heads, straighten warp heads etc. all the time (mainly Japanese and Korean) and have all sorts of rubber bungs etc. that they jam in to them to pressure test them in water when they have been repaired.  

 

If there is a shop near you that does Vapour blasting  ( high pressure water, air and glass beads) it leaves a nice smooth shiny finish on aluminium without polishing.

The photo is a head I had pressure tested and blasted a while ago.

Edited October 17, 2018 by DavidAU (see edit history)

[Restorer32]

If you do polish that head it will be a "never again" experience.

[auburnseeker]

13 hours ago, Curti said:

Some of the guys try polishing the aluminum heads on Auburns.  In my opinion they never look finished. It is like a paint job with orange-peel. 

Probably because most guys think you can buff rough aluminum, which you can,  but as you mentioned, the only surface that looks right is a smooth one to start with,  otherwise,  you are just buffing the high spots. Kind of like trim work.  Where the guy buffs it all up but never got the dents all the way out first. 

[Restorer32]

Depends a lot on how porous the casting is. 

[edinmass]

Even the Duesenberg factory display and show engines were only selectively polished in some areas.......it was just too much work.........Cleaning up a casting to look good is LOTS of work. More than most people can imagine.

[viv w]

I agree with Curt, trying to clean up an aluminum casting either by wire brushing or polishing never gives a satisfactory result, you will always have areas that you cannot get into properly, and it looks "tacky".

 Glass bead or vapor blasting gives a nice even natural color .

Viv.

[Buffalowed Bill]

Gary,

 

Before you waste your time on an original, talk to Bill A.  He just had a new one cast. Depending on how it works out, he might consider having a run of these made. I have an original that I had tested and repaired for use on my coupe. It was tested to 125lbs/squ" using compressed air, but not sure that I am brave enough to use it.-Bill

[Stude17]

Many years ago I did my apprenticeship as a fitter and turner in a specialist welding shop where the foreman was the expert in repairing cracked cylinder heads (both aluminium and cast iron).  If I remember correctly one method I saw him use to test for leaks was to blank off any coolant outlets on the outside of the head (not the coolant holes on the machined combustion side)  and place the machined surface upright and level.  All the external surfaces were painted with a whitewash (water and a chalky substance) and allowed to dry.  The internal waterways were then carefully filled with kerosene and left overnight.  If there were any cracks or porous areas the kerosene would leak through and stain the whitewash.  This is how I remembered he would do it.  Would cost nothing to try it and from memory it was every effective.

[Gary_Ash]

I talked to Bill A. at the Studebaker meet in Tacoma last month about the aluminum head.  He said the foundry got the first one "almost right" - but not quite.  It seemed a simple, solvable issue.  At least the 3D CAD file exists for the head and core.  The core was 3D printed, so it's a one-at-a-time, expensive process, but the market for aluminum heads for 250 cu. in. Studebaker straight 8 engines is pretty small - say me, him, and maybe two other guys. 

 

I put the head in my degreaser tub, scrubbed it with diluted purple cleaner, and power washed it.  That made a good difference, but there are still some stained areas.  See photos below for before and after.  I'll go over it with some SOS/Brillo pads, maybe hit it with a little diluted ZEP-A-LUME truck wash.  I can go buy a bag of glass beads, dump the Black Beauty out of my sand blaster cabinet, and go at it gently if it still needs more.  I will resist the temptation to polish the head, thank you all!

 

Stude17's leak test method is pretty much what is done for liquid penetration leak testing.  A dye-containing solution is sprayed on the metal, allowed to sit, and then wiped or rinsed off.  Then, a developer solution is sprayed on.  Dye that oozes out of cracks can be seen against the white developer or under UV light.  I think it's the best method for non-ferrous parts.  The engine shop can do this for me.  You can buy a kit to do this for about $60:

https://www.pegasusautoracing.com/productdetails.asp?RecID=5922

 

For pressure testing, I would NEVER use compressed air because the part can fail and explode like a hand grenade [don't make potato guns out of PVC tube!]  Better to fill the part with water with a pressure gauge attached to the part, shut the water inlet valve, and see if the pressure gauge stays the same over an hour or so.  For these old engines designed with non-pressurized cooling systems, I'd be wary of going much over 10-30 psi for pressure testing.  With pressurized water, if the part fails, you hear a little "ping" and some water drips out, but no flying shrapnel.  I've done this on industrial parts to 3000 psi.

  

[Ivan Saxton]

It may pay to check Foley Pattern Company in Auburn; because if there was need in 1980s or at any time they may have cast new heads for Stude, as I believe they did for Auburn and Cord.   In 1984 I bought a beautiful Stutz transaxle casing from Paul Freehill.    Stephen Hands was a friend and Metco service engineer, and once he stopped for lunch with us accompanied by an English colleague who was in a similar technical advisory role interstate, probably in Sydney.   This man was describing how he repaired corroded Maserati cylinder heads with a machineable Metco self-bonding stainless steel powder coating.   I shall try to contact Stephen at Bendigo Swap in a few weeks time.

[John_Mereness]

Relatives had a 37 Lincoln Zephyr Coupe - they bought NOS aluminum heads and 15 years later with they were throwing those away (plus a couple other problems), but a friend talked about his father having problems with his Zephyr heads within the first 5 years of ownership.  The same relatives fought the battle on their 1935 Packard Twelve Convertible and eventually went to cast iron.  And I bought their 1932 Rolls Royce Phantom I (that replacement head was 20K from Frank Cooke in 1997 or so and another 22K to deal with all the problem caused to the rest of the engine as a result (radiator, water pump, ... and installation).  And, then their has been all our Auburns and a few other peoples too.    The flip side of the coin is there are a few Auburns running around with original heads.   My point though is: the aluminum head is really neat, but give serious thought to the  cast iron one on and just having a good time with your car. 

 

I personally like a course sand blast on aluminum heads - looks sweet. 

Edited October 20, 2018 by John_Mereness (see edit history)

[Buffalowed Bill]

Gary with all due respect, I think that it impossible to know what the demand for an original type aluminum head might be without doing some research. I have no doubt that at least forty or fifty 1936-37 Presidents have survived. Restoration is not all about the bottom line for some of us. If money was the only consideration, nobody owning a car having one of the 1929-42 engines would consider committing the the resources it takes to rebuild one, but we do. 

 

Bill A. is one of those people who is driven to get it right. After he found that using one of the original "Lionite," castings was so fraught with problems, he took it upon himself to do it  right. I look at it as a unique opportunity do what other marque owners have done, and make the commitment to authenticity. Please let us know how you feel about the process once you have done what I did, trying to save a "good" original, but still be unsure whether to use it. Your worthy project is your rendition of a clone, and as such you can produce it anyway you choose, a restorer may not feel that he has the same flexibility. 

Bill