Looking for input on a cylinder block corrosion issue.

[Eccentric]

I am looking for input on a cylinder block corrosion issue.

I'd like your opinion on this corrosion issue I have in my cylinder block. These pictures were taken after the first run of the engine which consisted of maybe five runs lasting from 10 to 45 seconds each. The coolant runs through a 3/8" clear vinyl hose and I could see the water taking on an increasingly orange tint as seen in the last picture of this series. At first I thought oil was getting in the water, but this was not the case. Upon disassembly this is what I found.

The engine is a twin cylinder, Westbury Wallaby IC 4 stroke engine.

At first I thought I was getting severe rusting of the cast iron cylinders in the aluminum block, but upon closer inspection, I no longer think so. I did not have any ethylene glycol in the water, as I probably should have. This is the amount of rust I would expect to see maybe over years, not over a period of a half hour and maybe 4 minutes of run time.



I believe this is some sort of thermal reaction of the Loctite I used; the discoloration is concentrated at the aluminum/cast iron interface. I used Loctite 638 (green in color) thinking it was high strength and high temperature and suitable for this application. I did not use an activator. There was probably about three week cure time between installing the cylinders in the block and the first engine run. It appears the Loctite heated up and out gassed. The engine always had a water flooded block as the tubing was above the engine level and I could see good coolant flow. Flow was from the bottom up through the head.

I do not think this is a simple issue of the cast iron rusting as areas away from the Loctite are clear of rust. It almost looks like a Loctite reaction or a dissimilar metal reaction. The cast iron is oxidizing where there is Loctite.



Thoughts anyone?

 

[ozzie46]

Are you using plain water for cooling? I use water mixed with antifreeze for the anti rusting it provides.
Ron

 

[stevehuckss396]

If you think it's galvanic reaction then try straight water and a product called water wetter. It has all the anti corrosion that glycol has without the surface tension. Cools 30 percent better than 50/50 coolant.

 

[mayhugh1]

I don't think the problem had anything to do with the Loctite.

You should be running a glycol mixture or some sort of rust inhibitor for coolant - never plain water. You have three different metals in there - stainless steel (bolts), cast iron (liners), and an aluminum housing. None of these like one another other in the presence of an electrolyte which the hot water surrounding the liners is waiting to become. Wet cast iron will begin to rust immediately, and once this happens the water carrying these microscopic rust particles is suddenly a very good electrolyte for galvanic corrosion. Heat from the liners accelerates the whole process by raising the temperature of the electrolyte. You can see in your photo the rather unexpected corrosion between the stainless steel bolt heads and the aluminum housing which resulted. The Loctite between the liners and the housing might in fact have saved the seals between the two.

Find someone who can bead blast the interior and once it's really clean (using a good solvent), use a wicking grade Loctite around the bottoms of the cylinders to help restore any damage. Cure the Loctite (I use 290) at around 150F for several hours. I leave mine in a welding rod oven overnight. - Terry

 

[grahamgollar]

This effect is occasionally found in full size diesels and is a result of excess coolant velocity. Over time it produces an appearance similar to woodworm attack or osmosis on a fibreglass yacht hull and the holes will 'bore' through the full thickness of the liner wall. Caveat emptor cavitation!

 

[petertha]

I had this idea to briefly immerse my cylinder assembly into my ultrasonic cleaner containing water & mild detergent in order to remove any traces of lapping compound. Within minutes, as soon as the bath temperature became warm I could see a light rust coloration starting to develop. Gasp. Out it came, quickly. Good thing I didn't walk away & let it go unattended. Its a cast iron liner with light interference fit within 6061 aluminum cylinder - no fasteners & no Loctite/retainer. This episode doesn't solve your coolant issue, but I agree with the root cause.

I've always wondered about this because I've seen other model engines like those stationary / hit-n-miss types which have a kind of water bath. I just assumed they were replenishing with regular water vs a glycol type mixture but maybe not. Or maybe they have another some trick, or more metal to sacrifice or...?

Also of note, some moisture got into my scrap box & seems like 12L14 can develop rust pretty easy as well. I don't know why I thought it might be a bit better corrosion wise, but might be the equivalent issue making liners from that material.

 

[Drawfiler]

Wet liner engines have been around for a long time so this is a problem with your setup, my contact in the UK who prepares competition wet liner engines uses Locktite 572 for this job as it the one they recommend,,I think your problem starts with ultrasonic cleaning, try putting a piece if CI in the cleaner and let it dry and watch for corrosion,
liner manufacturers will leave a faint film of corrosion inhibitor to stop corrosion in storage, you don’t have this,
as others have said, you need an inhibitor for cooling fluid, either a normal car one or perhaps go to waterless.

 

[Bentwings]

I don't think the problem had anything to do with the Loctite.

You should be running a glycol mixture or some sort of rust inhibitor for coolant - never plain water. You have three different metals in there - stainless steel (bolts), cast iron (liners), and an aluminum housing. None of these like one another other in the presence of an electrolyte which the hot water surrounding the liners is waiting to become. Wet cast iron will begin to rust immediately, and once this happens the water carrying these microscopic rust particles is suddenly a very good electrolyte for galvanic corrosion. Heat from the liners accelerates the whole process by raising the temperature of the electrolyte. You can see in your photo the rather unexpected corrosion between the stainless steel bolt heads and the aluminum housing which resulted. The Loctite between the liners and the housing might in fact have saved the seals between the two.

Find someone who can bead blast the interior and once it's really clean (using a good solvent), use a wicking grade Loctite around the bottoms of the cylinders to help restore any damage. Cure the Loctite (I use 290) at around 150F for several hours. I leave mine in a welding rod oven overnight. - Terry

there is a waterless coolant the racers have to use. Evan’ I think. It’s expensive around $25 per gallon it’s a super coolant besides . I used a bunch of zinc and magnesium anodes on my boat. Some were mounted in pipe plugs others just clamped on prop shaft rudder anodes were bolted on . I got a hand full of magnesium and zinc anode materials go my on hold boiler project . A friend has a supercharged small block chev engine . He uses the evans stuff . I called evans and spoke to a real person that knew things. He recommended removing the thermostat and any restrictions . The water pump is over driven so the coolant really speed through the engine We converted to a triple pass radiator which slowed flow down a little but it runs almost too cool now. My own super charged street rod had a pair of pipe lug zinc anodes and I had no corrosion in 15 years my Cummins diesel truck ran standard antifreeze I did put pipe plug anodes in however . My grand son has a Ford diesel that the coolant is like acid it coo rides everything . The Ford diesels have had problems with corrosion too has to do with vibration . Try the evans all he local racers use it . Mostly becausecthevracevpromoters only allow water or waterless . Standard anti freeze makes a big mess on the track surface

 

[petertha]

I think your problem starts with ultrasonic cleaning, try putting a piece if CI in the cleaner and let it dry and watch for corrosion

Thanks. Just to be clear, the OP is having corrosion issues related to running the engine with his coolant. One of the observations in post #4 was that elevated temperature accelerates corrosion rate in the presence of water. I'm just corroborating this with an non-running example of my own where I briefly put a CI liner/aluminum cylinder assembly into ultrasonic bath water at only moderately elevated temperature, no Loctite, fasteners or any other factors involved. Within minutes corrosion started to develop on the CI surface. So I would say 1) avoid ultrasonic altogether 2) I agree, elevated temperature aggravates the problem, even more so in running conditions. I used to use ultrasonic on some of my RC engines but the liners were ABC (aluminum/brass/chrome) which is probably why corrosion wasn't an issue. Exposed CI is a different animal.

 

[HMEL]

I am looking for input on a cylinder block corrosion issue.

I'd like your opinion on this corrosion issue I have in my cylinder block. These pictures were taken after the first run of the engine which consisted of maybe five runs lasting from 10 to 45 seconds each. The coolant runs through a 3/8" clear vinyl hose and I could see the water taking on an increasingly orange tint as seen in the last picture of this series. At first I thought oil was getting in the water, but this was not the case. Upon disassembly this is what I found.

View attachment 139549

View attachment 139550

The engine is a twin cylinder, Westbury Wallaby IC 4 stroke engine.

View attachment 139551

At first I thought I was getting severe rusting of the cast iron cylinders in the aluminum block, but upon closer inspection, I no longer think so. I did not have any ethylene glycol in the water, as I probably should have. This is the amount of rust I would expect to see maybe over years, not over a period of a half hour and maybe 4 minutes of run time.



I believe this is some sort of thermal reaction of the Loctite I used; the discoloration is concentrated at the aluminum/cast iron interface. I used Loctite 638 (green in color) thinking it was high strength and high temperature and suitable for this application. I did not use an activator. There was probably about three week cure time between installing the cylinders in the block and the first engine run. It appears the Loctite heated up and out gassed. The engine always had a water flooded block as the tubing was above the engine level and I could see good coolant flow. Flow was from the bottom up through the head.

I do not think this is a simple issue of the cast iron rusting as areas away from the Loctite are clear of rust. It almost looks like a Loctite reaction or a dissimilar metal reaction. The cast iron is oxidizing where there is Loctite.



Thoughts anyone?


View attachment 139552

View attachment 139553

It is very difficult to ignore the observation that the corrosion is occurring where the loctight is located. What you might consider is asking locktite if there are compounds or metals that would enhance corrosion and they would or should know. The corrosion is localized which looks like galvanic cell corrosion. Locktite might recommend a different product. If others have made this engine out of the same materials and have experienced no problems it would point to the locktite. Even the stainless steel bolts which should be ok on aluminum are affected. It would be possible to test this with a coupon in water but best bet is to start with loctite company. Its in their best interest to know they have a product that is not working properly. You might end up talking to their application engineer.
HMEL

 

[TonySteamHobby]

Do a web search on “flash rusting”. I have seen this many times in minutes.

 

[Eccentric]

I do beleive this is an example of "flash rusting". I was amazed at how quickly the corrosion developed and how extensive it was.

I have sand blasted the rust away, then rinsed in a mixture of simple green and water, rinsed in water, blew it all dry with compressed air and finally used a heat gun to warm the crankcase up to insure all the rinse water was evaporated. Finally I rinsed in Acetone. I then used Loctite 290 around the cylinder sleeves. This is very runny and was easy to rinse it around the cylinder sleeve and block joints. I let the crankcase set for a couple of hours, then I wrapped it in aluminum foil and put it in a toaster oven at 150 degrees F for three hours.

I will reassemble and do another run test. This time I will use the premixed 50/50 Antifreeze that is ubiquitous at auto part stores. I will let you all know what it looks like upon the second disassembly. Thanks everyone for your input. This has been very helpful.

P.S. I did not use a friend of mine's advice. He suggested I use muriatic acid to remove the rust. This would have dissolved my cast iron sleeves.

 

[awake]

Also of note, some moisture got into my scrap box & seems like 12L14 can develop rust pretty easy as well. I don't know why I thought it might be a bit better corrosion wise, but might be the equivalent issue making liners from that material.

Actually, 12L14 absolutely LOVES to rust - much faster to rust than plain mild steel.

 

[stevehuckss396]

Run eater wetter in your cooling water and a pinch of wd40 in your fuel and you won't need to worry about rust. I have had engines sit for over a year and still spin freely.

 

[Steamchick]

Hi Eccentric. I am from the "Car making" industry, but had 4 years in Engine Design before 28 years in QA...
In Engine Design I worked with the supplier's Chemist on LLC: "long-life coolant" and athe basic rules are:
LLC contains a lot of anti corrosion additives in the glycol, becuase glycol alone won't stop corrosion (of aluminium, iron, steel, brazing materials in steel tube assemblies, etc.) This is because the hot fluid - between 30% and 50% of Glycol in water - finds the electrolytic potential between differing materials to be an ideal condition for corrosion to apply. The Anti-corrosion additives of a good proprietary Coolant mix should eliminate all these corrosion problems.
But Do Not exceed 50% Glycol in water. It is a waste of money for no benefit.
Change the coolant after 3 years - because the anti-corrosion additives will be all used up soon after....(by 4 years-ish) - a time dependant thing, irrespective of running. If you drain the cooling system, flush out and DRY it. Any rusting that starts can be treated with a phosphoric acid anti-rust cure, "Curust" or " Naval jelly" are brand names used. This converts the rust at the surface of the metal into a bonded layer of iron phosphate - black - that acts as an electrical insulator, a few molecules thick. This reduces the electro-potential locally - where it was probably at the highest to cause the rusting in the first place. So cleaning back to bare steel/iron isn't such a good idea. But remove loose rust, as it is a waste of Curust converting something you will wash away. Just wipe off all the loose rust, paint with Curust, rinse and replace the coolant with proper automotive LLC, not JUST glycol mix.
(Glycol is an anti-freeze, not and anti-rust chemical).
Oh, the same applies in your car... Change the coolant for a proper LLC at 3 year intervals to avoid corrosion that will eventually knacker the water pump seals.... and use more money you could be spending on model stuff!
Cheers,
K2

 

[HMEL]

I am looking for input on a cylinder block corrosion issue.

I'd like your opinion on this corrosion issue I have in my cylinder block. These pictures were taken after the first run of the engine which consisted of maybe five runs lasting from 10 to 45 seconds each. The coolant runs through a 3/8" clear vinyl hose and I could see the water taking on an increasingly orange tint as seen in the last picture of this series. At first I thought oil was getting in the water, but this was not the case. Upon disassembly this is what I found.

View attachment 139549

View attachment 139550

The engine is a twin cylinder, Westbury Wallaby IC 4 stroke engine.

View attachment 139551

At first I thought I was getting severe rusting of the cast iron cylinders in the aluminum block, but upon closer inspection, I no longer think so. I did not have any ethylene glycol in the water, as I probably should have. This is the amount of rust I would expect to see maybe over years, not over a period of a half hour and maybe 4 minutes of run time.



I believe this is some sort of thermal reaction of the Loctite I used; the discoloration is concentrated at the aluminum/cast iron interface. I used Loctite 638 (green in color) thinking it was high strength and high temperature and suitable for this application. I did not use an activator. There was probably about three week cure time between installing the cylinders in the block and the first engine run. It appears the Loctite heated up and out gassed. The engine always had a water flooded block as the tubing was above the engine level and I could see good coolant flow. Flow was from the bottom up through the head.

I do not think this is a simple issue of the cast iron rusting as areas away from the Loctite are clear of rust. It almost looks like a Loctite reaction or a dissimilar metal reaction. The cast iron is oxidizing where there is Loctite.



Thoughts anyone?


View attachment 139552

View attachment 139553

You might be interested to know that the locktite fluid compatibility chart has a special exemption for potable water. Possibly because of the chlorine or other additives I would guess as potential problems. This loctite is not on the list. All other types of water are more tolerable to a number of products.

https://www.new-line.com/nldocs/resources/Loctite_Fluid_Compatibility_Chart.pdf
HMEL

 

[Steamchick]

I am not a chemist, but Loctite have help desks full of them. I guess there is a reaction between the coolant water and loctite that is acidic, releasing Oxygen ions at the steel surface that cause rusting?
The data sheet should cover water as an exclusion application in that case.
K2

 

[Charles Lamont]

If using water, I would use distilled. I have a ready supply in winter from the workshop dehumidifier. Also good for model boilers.

 

[Steamchick]

Hi Charles,
Distilled water is best in Steam Boilers, as it avoids sludge from saturated salts depositing inside the boiler. BUT De-ionised or distilled water is actually MORE corrosive than ground water. Technically it is slightly acidic I believe, as the free ions of WATER that will exist are highly reactive - or something - and any electro-potential between 2 different metals in the system cause a highly reactive degradation on one of both "electrodes" - called rust! So please use tap water, preferably harder rather than softer, as it is much less corrosive than distilled water. Save that for topping-up lead-acid batteries, and use in steam boilers.
Cheers,
K2

 

[Charles Lamont]

Hmm - interesting.