Hi all,

I'm rebuilding an Alfa 1.7 16v Boxer from a 33 that's been sat in my garage for 10+ years stripped, and thus isn't in the best condition (it wasn't great when I got it!).

The block is pretty rusty, the water jacket is full of rust & calcium deposits, and the oil ways are full of varnish.

I know I could have the engine hot tanked to remove the oils and grease but I don't think it would touch the calcium & the rust. I've been considering a few options:

1) Have the block acid dipped. There are a couple of companies in the UK that offer this service (though annoyingly far away), and this multi-part process would remove all of the calcium, oil, grease, and rust and after having inhibitor applied would make it the perfect surface for paint. Whats not clear is how much re-machining of mating surfaces would be required after this. The cylinder head mating surfaces need skimming anyway as they're in poor condition, but this block has front and rear plates and as they've got studs etc. in them I'd be less keen to have to try and prep these for skimming.

2) Hot tank & electrolysis. I could have the block hot tanked to remove all of the carbon & crap from it, and then run a multi-day electrolysis process to remove all of the corrosion. This would take longer and potentially not be as effective at removing all of the deposits inside the engine but it would be cheaper and less of a pain to find somewhere to do the hot tanking.

3) Wire wheel & Hot tank. The good old method of wire wheeling off all of the rust and then hot tanking the engine to clean it all out. My least favourite as the labour & risk of damaging surfaces is high.

Additionally there is quite a bit of corrosion in the bottom of the bores. I would usually not risk it and just bore out and fit oversize pistons, but it seems that the oversize pistons are NLA and after markets are extremely expensive. I suppose the answer is remove the corrosion, hone the bores and measure, but does anybody have any thoughts? I can get a photo tonight if it helps.

Can't advise on the best option.

When I rebuilt my Sierra 2.0 Pinto for my MK Indy, I stripped the engine fully at home, myself.

I then sent the...

Bare block (oily and rusty)
Bare crank shaft
Pistons (rings still on and rods still attached)
Bare cylinder head (with cam and labelled valves, etc.)

...ff to my local engine reconditioner.

It came back from them with...

The blockclean(but I still hade to wire wheel the rust off before painting).
Re-ground crankshaft + new bearings
New pistons & rings on the original rods
Cylinder head cleaned and reassembled (new valves)

If I were you I'd speak to an engine reconditioner (provide photos) and find out what process they recommend.

The Lotus TC I've rebuilt I filled the waterways with white vinegar for a couple of days and it brought them up a treat (used plastic to bung the core plug holes up etc)

I only cleaned the waterways though and not the bores as these were fine and just needed a light de-glaze with the de-glazing tool

The block I degreased and then used wire mounted points in a drill to get a nice surface to paint

I have never tried this but what about trying central heating cleaner ?
It’s just a thought I had last night
Jacko

Put the block in a tank of diluted oxalic acid, it will remove all the rust but not the sludge, I don't think there are many engine shops that still have acid tanks due to H&S, but if you find one good luck the block will come out pristine.if you know someone with a steam cleaner that should get a lot of the sludge out.

S

Unless you're wringing 3x the HP out of it than stock, don't worry too much about the water ways but the vinegar soak sounds productive for that, but it will make very little difference in the end unless you have a really thick layer in there.

Take it to a media blaster and let them have at it with dry ice blasting or walnut blasting. No need for chemicals, dips, worry of erosion etc and the outside will be ready for painting.

https://www.youtube.com/watch?v=RXR3a2WSgrM