Corroded engine assembly

[Deleted User]

I have engine No Y 8461 to resurrect that is in a badly corroded condition.
The engine looks like around 1921 but has twin plugs in the head with a plate cover rather than an aluminium water jacket.
The whole thing has been in diesel for 3 months, but I still can not shift the barrel from the case. Also, the pistons, both being at about mid stroke, are welded solid in the bores. I have heated to see if I could get the barrel to release from the case but no success. Even if this did become free, I could not get the rods past the crankpins as the pistons are solid.
I have heard of using Caustic soda but although the pistons could be considered sacrificial, the case must be preserved from undue damage.
I have heard of using phosphoric acid on the iron parts but have no experience of using it. Any experienced advice appreciated Roger

[Deleted User]

Try pouring boiling engine oil down the bores then drop a bit of copper bar through the plug hole (as long as they are in the top of the head that is) and begin tapping it with a hammer. Drastic but if you cannot free it this may be the only option.

Thanks

James

[BRIAN MARSHALL]

Hi.
This sounds like a hybrid engine, with early 1926 bottom end and 1923ish, top end. Are the plug holes vertical to the bores or angled? The rings are more than likely the very thick type and so have corroded and grabbed the bores over a much larger area than the later type slender rings.
I certainly wouldn’t let caustic soda anywhere near the engine, and phosphoric acid is a much safer bet, although I would do a dummy run on a piece of CLEAN aluminium first to make sure that it doesn’t attack it.
A much safer bet is to use concentrated Acetic Acid, and Hammerite Rust Removing liquid is just that, and costs about £12-00 per litre if you shop around on the internet. (Much dearer at local DIY shops)
It is absolutely vital to degrease inside the bores before you use it, and also ignore the instructions about dilution on the bottle. Use it neat, and leave in-situ for 4 or 5 days, before trying gentle taps onto the piston crowns with a hardwood drift.
Thoroughly rinse out the acetic acid before attempting to free things up and of course wear rubber gloves and full eye protection when handling the stuff. The big problem here of course is getting any chemicals past the edges of the siezed-up rings, top and bottom, and this is going to be a hard job to achieve success. Well worth trying however before thinking about brute force
Brian

[BRIAN MARSHALL]

Hi again.
Just had further thought on this, and IF the Acetic Acid doesn’t do the trick it becomes necessary to sacrifice something to get the engine apart. I THINK that I would probably cut thru’ the conrods first, and then at least you can get the barrel off the crankcase and attack the first problem from the underside. It shouldn’t be too hard to source a pair of narrow con-rods, and bear in mind “High Comp Harold” (The late Harold Caunt) whose Scott party trick was to cut con-rods in half, put them in a jig, and then weld the two pieces together again, making them a bit longer in the process to get a higher compression. About 20 years ago he told me all about it, but all I can remember doing is nodding my head wisely as he rambled on about eutectics and Oerlikon welding equipment. This was before I did a City and Guilds Welding and Fabrication course, and so most of what Harold told me went right over my head! He did emphasise that he had never had one break, and he was by repute a very skilled welder.I hope that my rambling may be of some assistance.
Brian

[Anonymous]

The main problem is of course the very brittle iron barrel, too much force in any place is going to crack it. Some methods I’ve used sometimes to free pistons stuck in bores is to do one or more of the following:

1. If the pistons are stuck above the ports you can fill above them with thick oil (50W or more) to the bottom of the plug thread. Now screw in a piece of bar with the M18 thread and it in effect creates a closed pressure cylinder. You can exert many tonnes of pressure equally across the piston crown doing this, but you risk bursting the iron barrel. You can acheive a similar effect by filling with water, plugging the holes and putting it in the freezer, taking advantage of the fact the alu piston will contract more than the bore. Again you risk bursting it though but it is a safer method than the oil one. If inlet and ex ports are open you can make a 1/4″ plate blanking plate to close them off. Ice is your freind and your foe with engines!

2. If pistons are below the ports you can screw a profiled bar down the plug hole to load the crown with a force then use a CO2 fire extinguisher up from the crankcase door to freeze the piston, again hoping the contraction is enough to free it. You can also buy freeze spray from DIY places that does the job, it is used by plumbers to temporarily seal off pipes.

3. I was out of options on the last engine I had with siezed pistons (20 years sat outside with no carbs on!) and in the end it got a profiled nylon bar down the bore and struck with a lump hammer while someone held the crankcase to prevent the shock going through the case. It worked, much to my surprise, but is a last resort.

As a side note I’ve got complete engine Y8286 here.

Good luck, let us know how you get on.

Cheers,
Richard

[Deleted User]

Have a friend, who poured Coca Cola into a Ford GT4o with stuck pistons, and serious, I have heard the suggestion from several

[Deleted User]

I have seen that coca cola trick myth being busted at the Mythbusters show on Discovery Channel. But hey, it might be worth a try!

[Deleted User]

Firstly you’ll all have to excuse my ignorance but am I right in guessing that this “Y” type engine has the added complication of a one-piece head and cylinder block?

I suppose the two most important components are the crankcase and the barrels so in extremis everything else is sacrificial.

While we know that the pistons are solid in their bores are there any studs adding to the problem?

Heating an assembly is a popular and fairly simple method for loosening parts and can be successful even if it was not in this case. There is a practical upper temperature limit, it would generally not be safe to raise the temperature by much more than 250°C above ambient. The biggest “BUT” with a heating cycle is that while everything expands the things that are expanding the most are the pistons and they are expanding at a rate just about twice as fast as the iron barrels. Now while heating may well loosen things up the differential expansion is really working against us by crushing things together rather than opening things up. At a temperature of 270° (20°+250°) the piston wants to be 0.4mm (0.016”) bigger than the bore and anything ‘crusty’— corrosion, carbon, what-have-you, will tend to get crushed into the softer aluminium. While this might have the desired loosening effect it will also tend to turn the piston into an effective lap and thus more or less unfit for further use.

So how about going the other way and making things shrink? One thing that has not been suggested so far is Liquid Nitrogen. It may sound horrifically Frankensteinian but given sensible precautions it would be worth a try, it might give you frostbite but at least it’ll not poison you, dissolve you or for that matter the engine too! Liquid Nitrogen boils at -196°C, if the whole thing can be cooled that far the piston(s) will shrink by about 0.15mm (0.006”) more than the cast iron. Now that should loosen things up a bit! It would of course be wise not to just dunk the thing but to take the temperature down slowly to avoid stressing the thing too much, things get brittle as they get colder and cracks would just about put the tin lid on matters not to mention the safety aspects! To save on Nitrogen a liberal quantity of ‘cardice’ to cool the thing first would save a lot of gas.

While the engine is cold there might be an advantage to introduce into the barrels a mixture of a volatile and a very light oil which, with a bit of luck, will creep by capilary action down the sides of the pistons.

Time to befriend the local University or someone else with a SEM – EDX scanning electron microscope!

On the subject of the other materials suggested:
Aluminium and its alloys are prey to all alkalis; Caustic Soda will quite vigorously attack aluminium but will not harm iron or steel.
Aluminium will not be seriously affected by Phosphoric Acid but it does convert rust to an Iron Phosphate. The down side is that the conversion tends to expand the volume, quite the opposite to what is wanted!
Acetic Acid will have little effect on either metal.
The “active” ingredient in most cola is Acetic Acid, good for cleaning brass but not much else.

[Deleted User]

Some years back, working on an old tractor, I had the same problem and brake fluid freed it as it is very searching. Another very searching liquid is glycol based engine coolant. I once put some of it neat into my Scott radiator and it came straight through the water dome gaskets and formed a large green puddle on the floor. I drained out the remainder, filled up with water and not a drop leaked out so I now use a weak solution which is OK.
Regards,
Bob Mather

[Author]

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