Seized Engine Cures

MYStargazer

MYStargazer

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Following an accident with my charge air cooler, some saltwater has found its way into the cylinders. I did't know this could happen, but it has.

That was three months ago... yes, I know I should have seen to it straight away but I had no idea one was connected with the other...

Does anyone know any way to unseize pistons? I thought of putting WD-40 in the injector ports, but someone has suggested tipping in diesel and leaving for a couple of weeks.

All thoughts gratefully received. Thanks.
 
In my experience, you remove the head and piston, the latter by unbolting the big end and knocking out with a wooden drift. On my 1GM that means turning the engine upside down. If you're really lucky, either free or replace the piston rings, reassemble and Bob's your mother's brother. If you're unlucky other components will have been damaged and can include the injectors, the pre-ignition chamber (shot blasting and skimming) and one or both pumps. All depends on how it got in there in the first place, if it was just a failed antisiphon valve, then the minimum damage scenario is quite likely. If it was water in via the fuel tank then the maximum damage scenario applies. In your case, it sounds like you might be lucky.

I found the best way is to do the donkey work yourself and take the bits to an expert to inspect, and advise on rebuild or replacement.
 
Heat some oil in a pan & pour it onto the piston crown, leave for 10mins then drift piston out with the stale of a hammer, works every time.
 
Morph What engine model do you have?

If its a Yanmar 1GM 10 they had problems with seawater getting into the head, so even if you unseize the pistons you still need to sort the cause of the problem

Peter
 
It's a Ford Thornycroft 6-cylinder, but alas there's little room for working underneath without cutting the cabin roof open (it's been done before it seems) and removing the engine. Am thinking of in-situ solutions first...
 
no penetrating spray is going to dissolve the iron oxide (rust). once the rings are freed up any lubricant would help everything move more easily.

I have previously got away with just running an engine with slightly rusty bores rather than stripping but it does depend on how bad the rust is.
 
A mixture of parafin and lub oil can do the trick, take the injectors out and fill the bores with it. Let it soak in for a week or two and turn the engine with a socket on the crankshaft pulley, either way will do but slowly does it, no point in rushing, let the oil get into every bit of rust in the bores.

Having freed it off the next job is to get rid of the parafin and change the engine oil.

Replace the injectors and try to start it up - it will smoke a bit (a lot). Let it idle for a few hours, dont rev it hard or let it drive anything. This will wash the parafin out of the exhaust system as well as applying heat and fresh oil to the pistons. The heat will help the rings free up if they are stuck.

With a bit of luck the bores will be "ok"and the rings will free off - it will never be a wonderfull lump but it it should run for a few more thousand hours.
 
If the water ingress was into one cylinder then it would be possible to turn the engine so that the siezed piston moves downwards away from the corrosion. But if it is more than one then it's most likely that you'll have at least one piston trying to come up over the corrosion and that's just not going to happen.
If you can get under the engine and remove the sump then it may be possible to take the bearing cap off and manipulate the piston downwards. If this is possible then a bit of emery to clean up the barrel and the problem should be "easy" to solve.
But seriously, if the salt has started to corrode the piston and the barrel, you have a seriosuly better chance of flying than moving it other than with a lot of brute force and regrettably I don't think that will be possible in-situ.
 
If as you say the water has come in from the aircooler then it will have come into contact with your inlet valves and seats etc, do you know if a lot or a bit of water went in.
if its a lot then engine strip is the way to go, if a bit i suspect by your post your knowledge of engines is not huge it might well be worth getting someone a bit more expierienced to have a look at it, because some of the comments on here will lead you to very costly engine repairs.
 
It's a Ford lump, they're pretty robust units so like the other posts I'd take the following line first as you've realistically little to lose and a lot to gain (meaning cutting away the cabin roof to get it out!) Always take the simplest/cheapest option first - so chuck some light oil down the cylinders via the injector holes and try and work the engine with a socket bar on the crank pulley nut. If you can get it to move only a fraction it has become unseized and you're on the way! If you're lucky you might be able to reverse the pull on the pulley nut without undoing it in which case you can work it backwards and forwards until it frees up enough to turn right over. If you can get it to turn over without injectors (and therefore no compression to fight against,) I'd spin it over with the starter to complete the freeing process but do put some rag in the injector holes as you'll have oil everywhere.

Good luck anyway, it's worth persevering as it's unlikely to have pitted the bores too deeply and if you can ultimately get it to start it'll soon fill up small pits with a bit of carbon and begin to run sweetly again. However, you absolutely must sort out the problem that put water into it in the first place. Finally, change the oil and filter as you do not know how much contamination you've actually got.
 
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