Aluminum Oxide -- Any Chemists in the House?

[salamandrrr]

I am presently wrestling with stuck to block heads, and the theory is that Al2O3 is one hurdle. Here's some tidbits from the web:

1. Al2O3 adheres strongly to the metal's surface.

2. Both its strength and abrasive characteristics are due to aluminium oxide's great hardness (position 9 on the Mohs scale of mineral hardness).

3. Therefore, aluminum will dissolve in hydrochloric acid and sodium hydroxide solutions.

Question:
Does WD-40 and PB Blaster dissolve aluminum oxide? If not, what should I use? Maybe Hydrochloric acid or sodium hydroxide?

Thanks Chemists,
Sal in Norcal

[MarcusHMM]

I would say neither. Is the block out of the car? And have you tried heating and some soft persuasion from a dead blow hammer? I would tend to think that it is head gasket/sealant that is holding it together.
Putting acids in the mix will just cause major problems down stream. Get something thin and hard to wedge at a corner and carefully work it in and use some leverage and shock therapy (ie: soft hammer or hard hammer with wooden block to protect the head and block as you whack it.)

If you have some stainless thin wire or thin piano wire you can get it started and "saw" through the outside and then pry it up and work some more. Slow, careful and take it easy.

Marcus

[sh0rtlife]

10-1 odds its the head gasket and or the head studs holding onto it...effort and carefull prying is required

[papajam]

Please give this thread a read.

[mjr]

you should post in your existing thread so everyone has the full history.

if dealing with a mixture of aluminium and steel corrosion from the studs,pulling alone wont shift it. you need to dissolve it with phosphoric solution, rattling it and diesel soaking. It always works, but takes time.

you need to find out if the material spec in the head and piston crowns contain any appreciable amount of magnesium. if they do, any acids are a bad move. If the heads contain no more than 2-3% magnesium, which is a common strengthening percentage, then 70% phosphoric solution down the stud holes over several hours , followed by thorough flushing should shift the corossion. you will need to repeat this several times. the phosphoric will dissolve the rust on the head bolts and theory is it will help to break the seal. Along with this you might try rattling the area with an air rivet gun on a block of wood at the same time. keep the power low so as not to crack the head. short bursts only. the vibration will help to break loose the desolved corrosion. be sure to flush regularly with the carb cleaner. you must throughly de-grease before putting phosphoric in, or it wont react.carb cleaner is good for that too. once you have done this method a couple of times, soak the stud hole with diesel for a day, then go for it . have an assistant rattle the area again intermittently, whilst you lever, and it will eventually give. you may need to repeatedly seat the head and unseat it to help it past the softened corossion.

test a small clean area with the acid first. if there is any minor fizzing or bubbling whatsoever, then u cant use this method.