Cleaning a Seriously Grotty Aluminium Engine Block

[revilla]

I've acquired a K Series block. Looks to be mechanically and metallurgically sound, but it's disgustingly gunked up! Ultimately I'll probably end up getting it soda blasted but it feels like it needs an initial clean first. Gunk Ultra and a toothbrush usually gets the oil and grease off but this one is so bad, you could actually scoop the stuff off with a spoon. Thick layers of a congealed hardened tarry grime that take ages to penetrate with degreasers. Never had to deal with one quite so grotty before.

Don't even think of suggesting bunging it in the dishwasher, my life would not be worth living.

Any experience of / advice on chemical hot tanks / acid dips / anything else?

Soak it in a big plastic box with a couple of gallons of paraffin likely to do much good softening it all?

Would any of the above make a decent job of cleaning out rust and coolant deposits from inside the coolant galleries?

Given that it will get blasted it doesn't need to be brilliant, just need to get it presentable for the next step of the process - preferably cheaply!

Thanks,

Andrew

[SM25T]

But she is out of the country ... are you a man or a mouse ?

[Jonathan Kay]

Thick layers of a congealed hardened tarry grime that take ages to penetrate with degreasers.

That's with a solvent, not a detergent? Does heat make a big difference?

...

You didn't mention a domestic pressure washer or a rented steam washer...

Jonathan

[7 wonders of the world]

Seen some good results from a friend doing a ground up rebuild of a Mustang using Citric acid, bought in powder form and mixed with water in a 40 ltr plastic tub.

Gave good results on steel and ally too.

[revilla]

Ian, she may be out of the country but she's left two little spies behind to keep an eye on me!

I usually use this stuff: https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.granvilleoil.com/techData/pdfTechData%3FptdID%3D277&ved=2ahUKEwjtqqGjzuHlAhUEQhUIHXcGAoEQFjAAegQIAxAB&usg=AOvVaw0KZusSjIyv4C765NnFYtJ7&cshid=1573456639448

On most oily greasy deposits it's almost miraculous. Just spray it on and rinse or wipe off, does what it says on the tin. I usually work it into thicker deposits with a stiff brush (old toothbrush works wonders). It seems to struggle to penetrate this though.

Water soluble, I'm guessing the action is that of a detergent, it's certainly not a concentrated organic solvent. A pink water based fluid that looks remarkably like coolant with a very mild clean smell.

Will have to look into citric acid.

Was thinking that a good soak in a solvent would probably soften it all up and make it easy to remove with degreaser. I've got some really large strong plastic storage boxes thay will take the castings, my first plan of attack was to put it it one of those with a couple of gallons of paraffin and leave it to soak for 24 hours and see what happens. Paraffin seems to be pretty good at penetrating and removing organic sticky stuff and it's inert enough that I know I would risk doing any damage to the metal.

The (lazy but convenient) alternative would just be to take it to a place where they do engine reconditioning and get them to put it through whatever cleaning process they use. It's the pros and cons of the different process available that I'm not so sure about.

I've had a few blocks soda blasted and the results are amazing; clean shiny silver cast alloy finish, they look absolutely spotless and nicer than when they left Longbridge. But I've never presented anything quite this grotty for blasting, I don't know how clean they need to be but as it stands I think it would be a bit much!

[revilla]

Grotty:

Took me half an hour to get this one patch to this state:

Where I need to end up eventually (one I had soda blasted before):

[ECR]

I'd be surprised if a paraffin soak and a domestic pressure washer wouldn't shift it .....

[Jonathan Kay]

Water soluble, I'm guessing the action is that of a detergent, it's certainly not a concentrated organic solvent. A pink water based fluid that looks remarkably like coolant with a very mild clean smell.

Yes. Granville Gunk Ultra Engine Degreasant contains an anionic detergent in "kerosine".

Seen some good results from a friend doing a ground up rebuild of a Mustang using Citric acid, bought in powder form and mixed with water in a 40 ltr plastic tub.

I still don't understand citrus-based cleaners as degreasants. They're (once again) widely used to remove lime scale etc, and have that effect by forming soluble compounds with insoluble inorganic crud. I use them on the bikes. Citric acid is pretty safe, has a nice smell (I'm told) and feels more environmentally friendly. But I suspect that any degreasing property is due to detergents or solvents in the formulation rather than the citric acid. If anyone feels like naming a particular commercial product I'll try and find out what's in it. And I'd be even more interested in a controlled test of the degreasing ability of citric acid on its own.

Jonathan

[revilla]

Jonathan,

I think that data sheet is for a different product in the "Gunk" brand range.

I remember when I was younger that engine degreasers were generally nasty flammable organic solvents and that sounds like the kind of thing that describes, especially if described as being dissolved in "kerosine". It sounds like using that stuff is not far off a good soaking in paraffin.

The spray on / rinse off Gunk Ultra that I use appears more like a pink coloured soapy water (but much more effective, in most cases it's quite miraculous stuff). It's clearly an aqueous solution of something(s), and I'm quite sure won't burn or form explosive vapours as described in your data sheet.

In fact I can't find a full data sheet for it but whilst typing this I just did a quick Google search and found this, describing it as "Non flammable".

I think I'll go with a paraffin soak and pressure wash first and see what happens. Will report back!

Andrew

[Jonathan Kay]

Sorry.

How about this one?

Jonathan

PS: Why don't vendors link directly to safety data sheets?

[revilla]

That looks more like it. So it's basically an alkaline solution of shampoo  Well it works well for sure.

[revilla]

OK so maybe I was making a mountain of a molehill here ... a couple of hours in a bath of paraffin and a quick scrub with a stiff brush and I'm already wondering whether I need to bother getting it blasted!

[ECR]

[rj]

Not so strange Andrew. If it has been covered with oil all it's life it has had no chance to corrode

[SM25T]

Sounds like a good way of cleaning up muddy children.

[nickh7]

If you need citric acid in powder form let me know and I'll get it for you from work

[revilla]

Thanks Nick. Ian, are you suggesting I dunk them in paraffin or citric acid?

[Golf Juliet Tango]

I'd suggest a pressure hose is best suited to muddy children.

[revilla]

Definitely an improvement:

[Jonathan Kay]

Did the paraffin bath clear the passages as well as cleaning the outside?

Jonathan

[revilla]

It rinsed out the oilways but the brownish deposits in the coolant galleries are clearly not oil-soluble. The pressure washer took some of it out, but I'll be getting this and a couple of other blocks soda blasted and I'll get them to wave the blaster into the galleries to freshen them up.

[Jonathan Kay]

Thanks.

You could try citrate on those...

Jonathan

[Mechanical Moz]

I had a heavily stained block vapour blasted at a local motorcycle restorers. Expensive but the results were excellent.

https://www.lotus7.club/forum/techtalk/liner-heights-took-far-too-much-block

[revilla]

And the final results after paraffin tanking, soda stripping and vapour blasting ...

I think I'm going to need to wear sunglasses to work on them now!

[ECR]

It's a real pleasure to work with parts like that though ...