Cylinder Block Corrosion

[Gannet]

I posted a comment on Jon's 102 data topic on cylinder block corrosion, but realised that it is a topic on its own.

I posted:-
I would have thought that a flush out with fresh water would have got rid of all the salt.
I think the problem is that the cylinders are left wet, (after they have been flushed out), and they probably remain wet/damp for days/ weeks/months depending on the climate. They are very much enclosed and so offer ideal corrosion conditions. How can they dry out? Air flow through it must be minimal. Running dry for a few minutes would help.
I do not think the corrosion has anything to do with the time spent running in water, but the time spent damp with air (oxygen) present to do its deadly work.

I have a raw water (in this case salt water) diesel engine which has spent 6 months of every year for 30 years full of salt water; followed by 6 months of every year full of fresh water antifreeze mix. There is no significant corrosion. I am sure it would have been a different situation if it was flushed out at the end of the season with fresh water and just drained of all water to provide a nice damp oxygen rich environment. Corrosion would have been rampant.

Jon wrote in reply:-

each to their own with regards to corrosion/rust prevention.
having looked through some previous posts on this subject i am still of the opinion you MUST flush the motor through with plenty of fresh water after each use in saltwater. that goes without saying for ALL of us- yes!
NOW, looking into this a bit more, i have said in the past that when testing your engine in a bin its usually a good idea to make sure the water is clean.
BUT HANG ON A SECOND
these seagulls do tend to "dump" a lot of oil out of the exhaust and into the water, so that the water you are testing in is now EMULSIFIED with plenty of "oily goo" and i beleive this "oily goo" is GOOD for the waterways when the engine is lying dormant for months on end! (does that make sense)

you could however try some sort of water dispersent spray in the waterway which would do pretty much the same thing.

JEREMY
your comments on the air being a factor for rust/corrosion are spot on!
stop the air getting to the metal and in essence you reduce the rusting and corrosion.

i'm not sure if anyone else does this or not but run the motor for 1-2 mins (BUT NOT IN WATER) at a slow idle to help dry out the internals before storing the motor away.
you'll probably see a fair bit of steam coming out of the water outlet but thats ok, its drying out.(i've run a motor like this for nearly 5 mins with no ill effects, just dont rev the motor, a slow idle is what you're after)
next thing is to try and seal any openings that would allow air to circulate (i use tissue paper soaked in wd40 to plug up any holes)
that would include the exhaust outlet, water outlet and the carb inlet (throttle closed and choke on) and if your motor has the "flute holes" on the exhaust tube block them up as well.
this is all about stopping the air getting to the metal, as long as you've followed a basic "LAYING UP DRILL" and use plenty of oil to lubricate everything, then the next time you go to use the motor it should be as good as the last time you used it.
BASIC MAINTENENCE at the end of the day

[Gannet]

Yes, there are several solutions to this, but the actual problem needs to be fully understood and defined.

Tales of corroded cylinder blocks on this forum are quite common. 102s especially seem to figure a lot - possibly because there were a lot of them and they are all quite old now. But the square block engines suffer as well.
The corrosion occurs, I believe, because they are put away/stored/dumped in an unheated shed/garage where the block probably takes weeks/months to dry and even then in a humid climate (like the UK's winter) it might never get really dry.
In other words the block is wet/damp and supplied with air (oxygen) - ideal corrosion conditions. If you really want to help the corrosion along, run the engine in water every month or so. That will ensure that it is always nicely damp!

I think salt water isn't the problem - provided its flushed out. As Jon states, this is very important.

The solution to this problem are many and varied. Jon has suggested some.

Are there any others?
One 'solution' is to say it will take years for the corrosion to be really serious and then it wont be my problem!
But there are other action that one can take.

Jeremy

[Charles uk]

Jeremy I seem to not agree with many of your points above,

Silver Century cylinder blocks seem to be the worst affected cylinders & much of this can be attributed to the change of the iron mix away from "gutter iron" to whatever in the 60's.

Cast iron & aluminium by their very nature are porous, & it's my view that it's salt that seems to end up in these spaces after use in the sea.

I built a 170 using a new cylinder for a race in Bermuda, tested & did the round the island, flushed & cleaned the motor & returned home, stripped & inspected the powerhead & left the parts on the shelf in the house, when I picked up the cylinder to reassemble the water jacket which had been painted inside & out by Seagull, had bubbles of rust coming through the internal paint, probably caused by humidity inside the house.

I once bought 3 Silver Centurys from a company that rented boats on a trout fishing lake, they'd owned these motors from new & had only used them on the lake, the motors were perhaps 15 years old & they had some of the least rusted water jackets I've ever seen.

As for dissolving the corrosion from inside the water jacket, read some of the earlier posts on the subject, up to now, no one has found anything readily available that is proven to do the job apart from Novamax & that is only available on an industrial scale.

[denchen]

I am not saying I am right but for years I have been putting `cutting oil` in the water of my test tank. Cutting oil for those not knowing is the oil put into water of lathes, drilling and milling machines that make the water go `milky` to help the cutters and protect the machine. I knew the oil as `alcalaid oil` but it seems that this term is not used today. I put the oil in to help prevent rust, neutralise the build up of any salts and a general lubricant.
As I said, I am not saying I am right but until I find good reason not too I will keep it in there.

[headdownarseup]

I'm probably a bit late in replying to this but bear with me.
Half the problem here is the fact the engine blocks themselves are made from cast iron, which as we all know is dreadfull stuff for rusting/corroding,particularly with a seagull if not properly maintained.
Not too much of a problem when on the outside of the engine block where a couple of good coats of paint will keep things in check for years.
The square block 40's and 100's are comparitively easy to rectify in the cooling department. once the cylinder head has been removed its all glaringly obvious!
However, i've always maintained the idea that if you use your seagull in freshwater there should be far fewer problems with rust.
Saltwater on the other hand has its own inherent problems.

Agreed JEREMY, the 102 cylinder on the other hand is a completely different beast altogether.(and dont worry about hijacking my other post its all good) Apart from removing the top and bottom water inlet/outlet fittings, there isn't much in the way of access into the block for descaling/cleaning.(except for the earlier cylinders with the removeable brass core plug/welch plug) but even then its not much better!

I've tried several different methods with varying degrees of success (mostly on 102 cylinders) and by far the most productive method i use is as follows.
1 strip down the powerhead following the normal procedures till you have just the cylinder remaining.
2 with some stiff wire (metal coat hanger or welding wire works well) have a really good poke around to loosen any large flakes of rust, a compressed airline will help as well.Give the cylinder a good shake and listen for anything rattling inside? When there's nothing "rattling" you're nearly there.
3 USE CAUTION HERE! Many different methods can be employed here but you will be using harsh and corrosive chemicals for this next step.
kettle descaler/caustic soda (or my preffered method of sulphuric acid from dead car batteries i get from work) UNDER NO CIRCUMSTANCES MUST YOU "DUNK" THE ENTIRE CYLINDER INTO THESE CHEMICALS, JUST THE WATERWAY/WATERJACKET MUST COME INTO CONTACT WITH THESE CHEMICALS. Use a peice of old rag stuffed into the cylinder bore to protect from any splashes of anything nasty.
Very carefully (steady hand) fill the waterjacket with your choice of cleaning chemical/s.
Leave for 24 hours and then flush with plenty of clean water. look at the colour change of the water when you do this.
Repeat the process again for another 24 hours. (it can take up to 5 times to get it good and clean, just depends on how bad things are to start with)
Once you're satisfied you've removed as much as you can swap to caustic soda and leave for 24 hours and flush out.The idea of using acid first was to soften and dissolve as much of the rust before switching to something else.

All the above will work very well on all of the square block engines as well. just takes time that's all (and patience) Basically , use whatever method you feel comfortable with either scraping/probing/soaking they all work in their own way.Some better than others.
Finish off with a few good coats of black heat proof enamel paint and job done! should last for a good few years to come provided you are sensible.

Thats the first part!

PREVENTION is something different again.
Various suggestions on the forum about using water dispersent sprays, various oils, sealing up any holes that may allow air to enter the engine internals which is where rust/corrosion starts.All of these will have some effect at reducing the speed at which rust/corrosion happens.
As per previous posts, air and water are the enemies here! Without air, rust is vitually nil despite the metal being wet/damp as in the case of the water jacket.
Stop the air from coming into contact with the waterjacket- no problem/no rust?

The problem for most of us with seagulls, unless you have a de-humidified environment in which to keep your engine pristine, then the only place we are likely to be able to store our engines will be in a cold/cool/damp garage or shed which just makes things worse!
SO ...... what to do?
Anything that anybody can add to this please share with us

jon

[Charles uk]

Gentlemen I suggest you do the same tests we did on these various chemicals you recommend, chop your next dead cylinder up with a band saw & collect the corrosion (some dust & some big lumps), red rust in one container & the black rust in a small air tight container, the black stuff will turn red in the presense of air.

Dry both with silica gel bags.
Weigh 5 grams of both the red & black & add to a sealed container of your chosen solvent, shake it up & leave for however long you feel neccessary.
Filter out the solids, dry & weigh.

The best we found on the red rust was Phosphoric acid which dissolved quite a lot of the dust but not much of the big flakes in 2 weeks giving almost 25% reduction in weight.
On the black the only thing that worked was Novamax which turned it from almost ceramic to black soup, but will leave a sandblasted woodgrain effect on the waterjacket walls.

Try it & let us know how you get on.

[headdownarseup]

CHARLES
can you explain to us "what tests" and with which solutions.

like you, i often use an acid solution for cleaning/descaling as i find this quite effective.
a case of fill and forget for a few days, come back to it and "hey presto", much of the hard work is done for you.

the bigger problem (in the long run) is with PREVENTION rather than remedial repair.

jon

[Charles uk]

I've tried
Kettle descaler.
Fernox DS3 boiler descaler.
Phosphoric acid rust remover.
Novamax which is used for descaling salt water injection pipes in the North Sea.
Other members have tried all sorts of stuff.

The test is put a dry weighed amount in a beaker & see how much dissolves over the course of time, you will need scales that weigh down to 0.1 of a gram.
You will be suprised how little disolves from the big lumps over weeks.

I felt Novamax at a 5% solution heated & pumped with a fish tank pump for 4 weeks might have been too aggressive for a cylinder made from unobtainium, so anything wartime or before.

Most of this has been covered in many earlier threads.

Remember a medium bad cylinder could have 50 to 100 grams of the poison in it, 3 or 4 cups of any magic descaler are going to have a job moving this, hence why I was using a fish tank heater/pump & a bucket of the mix.

It's the black iron oxide that seems to be the worst problem!

[Gannet]

Charles, I agree with what you say.

Yes, some blocks from some batches with a different (intentionally or otherwise) mix will resist corrosion better.
Yes, salt is nasty stuff.


I was trying (actually I think I made it very clear indeed) that a great deal of cylinder block corrosion occurs after the (wet cylinder block internally) engine is laid up in a unheated shed in the moist winter maritime climate of the UK.

I suggested that this is a big problem and perhaps has not been addressed sufficiently.

Jon and Denchen were kind enough to contribute their thoughts as to the solution. Both would be effective.
Their thoughts, like mine, were on PREVENTION, which can be considered in two steps:-
1.Remove (as far a spossible) the water from the cast iron.
2.Prevent (as far as possible) the air getting to the cast iron.
QED

I am sure that there are a miilion ways of doing this and also some much better sophisticated treatments that technically are available.
But what do you think we should do this autumn right now?

Jeremy

[Adrian Dale]

I have never used any of my gulls in fresh water simply because I have never lived close to a river or had the need to go looking for it .

The Channel between Bruny and Tasmania is a fabulous water way, scattered with beautiful bays, so it is natural to use the boat there.

I have owned one FP since 1981 and it has since seen service in Indonesia, the Maldives were for a year it served as a dive tender, Sri Lanka, Malaysia and Singapore. It has been in storage in shipping containers and in the hold in my yacht on which it was used as a tender, and in all this time has never had the head off or even the flywheel. Once when being towed it flipped in a gale force wind and was towed, unceremoniously, for several hours before a safe anchorage was found. On at least two occasions it was flipped in the surf when making a beach landing once Krakatoa, Indonesia and Phuket, Thailand. The last time it was used occurred only last week on the back of a 3.5 meter Avon with four people on board.

Now what I do is:

First flush with fresh water (use a copious supply), Drain and if available blow out with compressed air (in the past this was not often possible unless I had a dive cylinder handy), Turn upside down and squirt WD 40 or any substitute into the water passage, whip the plug out and squirt a small quantity of oil in, rotate the engine. Put the plug back and store for the next time after a quick wipe down with an oily rag. 140 in the gearbox and 1 to 8 in the tank.

If it was but to bed wet and full of salt I guarantee it would have rusted out long ago whatever the quality of the CI

My two cents worth: AJ

[headdownarseup]

A-J
on the face of it, your maintenence regime pretty much follows most of the rest of us here.
put to bed DRY but with plenty of oil in the bore and jacket. (i do the same)

i agree with JEREMY's comment earlier, its not neccessarily the saltwater or how often one uses their motor in the salty stuff, this is more to do with how you store your motor when not in use. I am an avid user of wd40, works great in a lot of uses (particularly when "winterising" an old outboard) and of course there are other products on the market that will do the same job. (some work better than others)

bottom line with this is it all rather depends on how well the motor has been looked after during its lifetime.
some owners are not so thorough with their maintenence/servicing and perhaps there may be some slight differences between certain engines in how they are made etc.

maintenence REALLY IS the key here. look after it, and it will look after you.

jon

[Gannet]

Adrian,

A great testament to the toughness and durability of these simple old outboards.

I agree with you whole-heartedly.
In respect of cylinder block corrosion:-
1.Use them in salt water
2.Flush out afterwards with fresh water
3.Put water dispersent oil (eg WD40) or dewatering oil in the water jacket.

Thats exactly what I do. The only difference is that I don't run them in the Maldives, Indonesia, Singapore, Malaysia etc. But given the chance I think that I would risk it!!!!

Thanks for your contribution - Knowledgeable, effective and simple advice.
Cheers.

Jeremy