Removing rust from water jacket

[Rob Ripley]

What about drilling (and tapping) an inspection hole in the offending spot and plugging it with a brass plug or screw?

[Rex NZ]

Stelios_Rjk

A liquid cold galvanising was tried here recently. It turned into a disaster. The cold galv bonding agent acted as a thermal barrier. That particular engine developed chronic overheating issues. The overheating was finally diagnosed down to the cold galv. This was stripped clean. The motor then cooled fine.

Have found mechanical scraping & picking of the water galleries an insufficiently effective approach for several reasons. There's a gallery between the exhaust port & base of the barrel which cannot be accessed, &, residual surface rust is a thermal barrier.

Locally we have a chemical stripper who specialises in rust removal on automotive unitary frames for restoration. It's a non-acid process, so, you don't erode the metals & leave the 'blasted wood' effect. Completely removes rust & paint. Will not even damage the surface finish on a honed cylinder. I live in a small town, &, New Zealand isn't the world HQ of engineering. So, I'm sure all of you will have access to a similar service provider.

http://metalpolishers.co.nz/

RexNZ

[Stelios_Rjk]

Your post was quite enlightening, thanks!
The liquid you use, did it contain much bonding agent? The spray I have creates a thin layer. I believe that it won't block thermal exchange. My main problem now is the hidden chamber at the point of the exhaust. I thought for once the solution of the oxide.

[fortyplus]

It seems that perhaps using something like this on a semi regular basis to prevent getting to the point of a major blockage might have benefits. It's a bit like using a radiator flushing product on a car, they are no use once the passages are blocked but can work well to clean scale etc. from slightly restricted passages and improve the transfer of heat, even in relatively open ones that just have a thin layer of deposits.

Has anyone ever tried Muriatic Acid, they sell it here for cleaning swimming pools, but it dissolves calcium and rust pretty well. We use it to clean alloy rims, spray it on wait 2 minutes wash it off and they look like new. It works well for removing rust stains off paint such as you get on a white vehicle, just don't breathe the fumes in or get it on you.

[Rex NZ]

Stelios_Rjk

I'd be reluctant to use any coating system. As an interesting note, 'Redline oils' sell water wetting agents to add to automotive cooling systems to improve heat transfer, not that they'll help an outboard.

Think back to your high school chemistry classes. All acids will react with the cast iron itself (as well as the rust) to produce iron salts & hydrogen gas. This erodes (translation-destroys) the casting creating the 'blasted wood' effect.

Suggest you dismantle the motor down to the bare block, then, send it to your local chemical stripper. Remember, it probably went rusty due to not being flushed after use, plus the passage of 40-60yrs. Once clean it'll take forever go rusty again. This is based on it's now being cared for properly.

RexNZ

[Stelios_Rjk]

Finally I found out something nice!

http://www.videojug.com/film/how-to-remove-rust

Enjoy!

[Stelios_Rjk]

Finally I found out something nice!

http://www.videojug.com/film/how-to-remove-rust

Enjoy!

[Charles uk]

Let's hope these pictures will give you a greater understanding of the geography of the Silver Century water jacket around the exhaust port.

When I sectioned this 9 months ago, all you could see was black iron oxide & shiney cast iron, any rust seen has developed inside a centrally heated house over that time, but please note it only happens on surfaces that were wetted with salt water.
I did break out some of the black stuff to see if it was magnetic, iron oxide rather than casting core plug sand.

You can see on the first picture where it first cracked on the exhaust port & the hole I drilled to see how thick this crap was, the cracks on the cut off end of the exhaust developed while it was sitting on the back corner of my desk, in the house.

[Stelios_Rjk]

Very nice job, I thought it would be somehow like this but now I have a good visualization. The question now is; Why the oxide in this chamber won't dissolve by using a rust remover? It would definitely be harder but to some point there must be a result.

[Stelios_Rjk]

DANGER DANGER!!!

Don't use stainless steel in rust removal by electrolysis. Hexavalent chromates is created which is poisonous and highly carcinogen.

[John@sos]

Well done Charles, nice to see what we suspected, thin and tortuous castings, OK if kept clean!

regards,
John
SOS

[OldBawley]

I row or sail our dingy, with a lot of wind and two persons a small outboard is better. Had a second hand Johnson 2hp for years, did not really like it. If the outboard is used it has to be 100% reliable, otherwise one could end up on the Egyptian coast. Furthermore the Johnson had a way of paying me back for my lack of confidence, he produced electrical shocks whenever I touched the running engine. Pulling a rubber wellie off and using it over your hand to regulate the gas is ok far from civilization but on nearing a crowded Mediterranean quayside it looks stupid.
So when I found a neglected Seagull forty Featherweight I bought it for 10 € and restored it.
Main task was unblocking the water channels. As everybody, I was afraid of removing the head so used Turkish kettle descaling fluid. It worked, I had a flow of water but noticed also that after heating up, the engine lost life. This forum learned me, head gasket gone.
No other way, so I started to remove the head which came off surprising easy. The acid had eaten the copper head gasket and made a hole in the aluminium head the size of a big bean.
Bought a new head gasket and had the head welded up. Flattening the head by file.
The acid had made a path for the water but 80% of the water channels was still clogged up. Cleaned mechanically.
I now have a outboard I can rely on, and it brings a lot of sympathy from the Mediterranean poor fisherman. My wife misses the Johnson. Not the way he run ( when he run ) but the expression on my face when I had received another shock. She could laugh all day. I once had a curled inside upper lip for hours from one of these jolts.
Beware of acid.

[Stelios_Rjk]

Thank you for sharing your experiences. I think I won't try acids on my two good blocks. At this time I am doing experiments with electrolytic derusting. The first results is that stainless steel electrodes cause carcinogen substances, electrodes from carbon are destroyed too fast and the derusting reaction is not so effective. A sacrificial electrode from ferrum is needed to see better results. For the experiment is used a broken and badly cracked silver century block. I will post pictures soon.

[charlesp]

Isn't electrolytic rust removal a 'line of sight' process?

[Stelios_Rjk]

I am not sure what you mean. I 'll tell you what I have observed and we will see if I get it. Rust is mostly removed from areas where the sacrificial electrode is right opposed. So yes, the water jacket still needs surgery..!