This thread applies mostly with flatheads(overhead engines with aluminum heads should benefit also) that have aftermarket aluminum heads. Electrolysis occurs when dissimilar metals are introduced to each other; example brass radiator,iron block, aluminum heads that starts a chemical process that “eats or erodes” the aluminum that if left unchecked can and will cause problems that can make certain objects unusable or JUNK. Having over 55 years of hi-po flatheads(if there is such a thing??) I have had over 20 sets of aluminum heads that after 2-3 years of running develop “soft spots” that get so out of control that renders many as useless “junk”. About 10 years ago,someone mentioned a “sacrificialanode” that when placed SOMEWHERE in the cooling system will attract the “barnacles” that attack and attach themselves to the anode. Many shapes and sizes are avaialable thru your local BOAT shop. You can purchase something too large and cut it to a size that can fit in your water supply and about twice a year remove it( I drill a hole and use 10 gauge WIRE that is attached to retrieve it), scrape off the offending barnacles and put it back in place. Over a period of time, the anode will be smaller and smaller and a new piece is required and the cycle starts over. Since using the anodes, little or no damage occurs and the life of aluminum products is greatly extended. The pics were taken from new heads that had about two years running time(not from my motor) but from a Merc engine I recently purchased. I would also recommend not using tap h20, but use water that is “cleaner” with less or no minerals.Also, your radiator should be “grounded” as small current(voltage) can be detected with a multi-meter that I have been told(can’tsay If this statement is true) adds to the chemical deterioration. Flatheads Forever! I am sure this will bring opposing views—-but I use big bore copper headgaskets(not the fiber—asbestos looking gaskets that were on this motor and take hours to get clean enuf head to reuse)) because I have re-used the copper gaskets over and over sucessfully( I don’t use any sealer either) with no problems. I am sure someone will differ and tell me the copper contributes to the problem, but has NOT caused me enuf worries where I don’t use them.Notice all the “problems” occur where water flows from the block thru the heads.Maybe, everything I have written here is not 100%factually true( just a hot rodder—not a scientist) but the anode just works well to make the electrolysis virtually disappear. NUF SED!
Ive been told about the annode before and plan to put one in my next set of heads. When you say no sealer you mean like nothing on the copper gaskets? Ive heard everything from spray paint, varnish, aluminum spray. Ive gotta say ive never heard of using them dry but im open to giving it a shot. Would be a lot less hassle. I'm assuming you still seal the studs?
Great idea. Cheap too!! Sounds easy enough to install an anode inside a radiator hanging off a wire. I’d say this is a good idea even if you don’t have aluminum heads. Here’s a good article on both zinc and the new aluminum alloy anodes. Thx. https://www.boatus.com/expert-advice/expert-advice-archive/2012/july/how-do-sacrificial-anodes-work
don't think that I have heard about Marine variable sizes of sacrificial anodes - have used radiator caps that use a flexible cable with sacrificial anode attached (getting hard to find) - also, have seen sacrificial anode attached to a threaded cap that is used at base of radiator instead of a drain plug - - the sacrificial anode does help protect motors of all types with aluminum parts
I throw a hunk of magnesium inside the water jacket before I bolt the water pump on. Whatever you use it has to have a higher electronegativity than the aluminum to be effective.
I've worked around water mains for years, to combat corrosion in dis similar metal situations , we have a specification for installing anodes on to the new pipe, also adding a stainless steel saddle requires a special coating on the pipe etc. When installing new water mains near a metro(subway) there are very specific coatings etc required due to the ambient current running thru the ground- I'm just now reading about alum heads on an iron motor block, and still have a lot to learn, will be watching this thread. Thanks!!
I use an anode hanging from my radiator cap on my 53 Merc with Navarro heads. Easy, safe insurance for my heads.
Boats use zinc for sacrifice plates if i remember correctly. Someone mentioned magnesium. What is the best thing to use in an auto engine?
Below is a table of different metals nobility. The lower the number the more chance that electrolysis will affect them. For example magnesium would probably be a very good sacrificial anode. Indeed boats have issues with electrolysis which is why they attach zinc anodes to propeller shafts (stainless) to protect them and bronze propeller and items attached to including the engine. The electrolysis can come from poorly installed electrical systems, stray electricity coming from boats tied next to them or even or even shore system electrical outlets. I never considered electrolysis between aluminum heads and iron blocks for dissimilar metal corrosion. It certainly makes sense. A sacrificial anode inside the cooling system of magnesium or zinc would certainly help. Galvanic Series - Scale of Nobility Whenever two different metals are placed in contact with each other, a galvanic reaction occurs which causes corrosion in the metal(s). Sometimes this can be used to our advantage - for example galvanising is zinc and steel (iron), and the zinc will corrode to protect the steel. This mix of metals is intentional and the zinc is regarded as sacrifical. However it is not always intuitive which metal will corrode. The table below lists various metals on the Scale of Nobility where for any combination of two dissimilar metals, the metal with the lower number will preferentially corrode (act as an anode) and protect the metal with the higher number (cathode). In the table below, zinc is No.4 and steel is No.30, so the zinc will corrode to protect the steel. Galvanic Series in Salt Water Scale of Nobility: least noble to most noble Anode or base end ( + ) 1. Magnesium 2. Mg alloy AZ-31B 3. Mg alloy HK-31A 4. Zinc (hot-dip, die cast, or plated) 5. Beryllium (hot pressed) 6. Aluminium 7072 clad or 7075 7. Al2014-T3 8. Al 1160-H14 9. Al 7079-T6 10. Cadmium (plated) 11. Uranium 12. Al 218 (die cast) 13. Al 5052-0 14. Al 5052-H12 15. Al 5456-0, H353 16. Al 5052-H32 17. Al 1100-0 18. Al 3003-H25 19. Al 6061 -T6 20. Al A360 (die cast) 21. Al 7075-T6 22. Al 6061-0 23. Indium 24. Al 2014-0 25. Al 2024-T4 26. Al 5052-H16 27. Tin (plated) 28. Stainless steel 430 (active) 29. Lead 30. Steel 1010 31. Iron (cast) 32. Stainless steel 410 (active) 33. Copper (plated, cast, or wrought) 34. Nickel (plated) 35. Chromium (plated) 36. Tantalum 37. AM 350 (active) 38. Stainless steel 310 (active) 39. Stainless steel 301 (active) 40. Stainless steel 304 (active) 41. Stainless steel 430 42. Stainless steel 410 43. Stainless steel 17-7PH 44. Tungsten 45. Niobium (columbium) 1%Zr 46. Brass, yellow, 268 47. Uranium 8% Mo 48. Brass, naval (Tobin), 464 49. Yellow Brass 50. Muntz metal 280 51. Brass (plated) 52. Nickel-silver (18% Ni) 53. Stainless steel 316L (active) 54. Bronze 220 55. Copper 110 56. Brass, red 57. Stainless steel 347 58. Molybdenum, commercial pure 59. Copper-nickel 715 60. Brass, Admiralty 61. Stainless steel 202 (active) 62. Bronze, phosphor 534 (B-1) 63. Monel 400 64. Stainless steel 201 65. Carpenter 20 (active) 66. Stainless steel 321 (active) 67. Stainless steel 316 (active) 68. Stainless steel 309 (active) 69. Stainless steel 17-7PH (passive) 70. Silicone bronze 655 71. Stainless steel 304 (passive) 72. Stainless steel 301 (passive) 73. Stainless steel 321 (passive) 74. Stainless steel 201 (passive) 75. Stainless steel 286 (passive) 76. Stainless steel 316L (passive) 77. AM355 (active) 78. Stainless steel 202 (passive) 79. Carpenter 20 (passive) 80. AM355 (passive) 81. A286 (passive) 82. Titanium 5A1, 2.5 Sn 83. Titanium 13V, 11Cr. 3A1 (annealed) 84. Titanium 6A1, 4V (solution treated and aged) 85. Titanium 6A1, 4V (annealed) 86. Titanium 8Mn 87. Titanium 13V, 11 Cr3A1 (solution heat treated & aged) 88. Titanium 75A 89. AM350 (passive) 90. Silver 91. Graphite 92. Gold 93. Platinum Cathode or noble end ( - ) Note: For any combination of dissimilar metals, the metal with the lower number will preferentially corrode (act as an anode) and protect the metal with the higher number (cathode).
During my sabbatical from the HAMB I had a Cosworth vega. original owner passed and the car had been sitting for 14 yrs in a cluttered single car garage.. got it running only to find on its 4 drive (first time away from neighborhood) the cylinders were rotted due to electrolysis/ corrosion from sitting with antifreeze in it, it started to smoke bad it warmed up as fluid leaked into areas it was not supposed to.. aluminum motor/ heads can be a pain.. not good to let them sit. Not sure I would do an alumimun block again..
That sounds like millions of engines from the late '60s up, that seem to hold up just fine. Was proper antifreeze with corrosion inhibitors used?
< I've always had trouble with corrosion on this car. I even lost a thermostat, thermostat housing, clutch cable, throttle cable, and an aluminum radiator. This radiator always leaked since I got it (15 yrs ago and 110,000 miles). Never knew why, but now I believe it was electrolysis from the beginning. I even have extra grounds on this car (fiberglass) and took good care of the coolant, but it always came out rusty. Even the head bolts were rotted off on the part that went through the deck to the coolant. Recently did some research and found out about boat zinc anodes. I found this site and they have everything you need to protect your motor with aluminum parts. Got one coming! 1/2" NPT, 2" long, 5/8" dia. They are cheap @ $7.29! Screws right into the bottom tank on the new radiator. https://www.boatzincs.com/engine.html Here's the old one...
Montanal, try more grounds. I ground everything when I wire cars, ten gauge being the wire of choice, I ground the rad to the frame and to the engine, it may be overkill, but a small current is generated by the movement of anti freeze, the body is grounded to the frame and engine, and the battery cable is grounded to both the engine and frame. I have never had issues, maybe luck, but I used to have a dog that puked in the truck, my parts guy sold me a ground strap that drug on the ground, said the static in the car made dogs and kids puke, sure enough it worked. My dog stopped that day, I have a ground strap on all my cars now, it makes people tell me something is hanging from my car.....
One thing to keep in mind for galvanic corrosion to occur you need a few things: dissimilar metals (increasing the nobility rating difference will accelerate the rate of corrosion), electricity and you need a electrolyte, Antifreeze with anti corrosion additives will help, but also remember your antifreeze is becoming MORE electrolytic over time. When possible pick materials that are CLOSE in nobility (The rating of 1, 2, 3 etc are somewhat misleading as the differences between materials aren't that nice - instead look at the voltage ratings) When possible - electrically insulate your materials. CHANGE your coolant - as mentioned earlier it becomes MORE electrolytic over time - making the situation worse And as mentioned a sacrificial anode is also a great idea. Food for thought YMMV
TrollsT, I have a ground from the battery to the bell housing on the engine, one from the the side motor mount back to the frame, one from the intake to the cab for the gauges and lights, and this time I grounded the radiator to the frame and I ordered a zinc. Should be here any day now. I never tried a Tennessee Go-faster (this thing is fast enough!), and I don't have a dog. Maybe I should borrow my son's dog to test it out, but I don't like dogs for that reason!
I have an anode from Boatzinc.com screwed into the water temp port at the top of my aluminum Canadian heads. From the outside it looks just like any other brass plug used to plug an unused hole. I've switched it out once in a dozen years. The old one wasn't really corroded though. I keep the antifreeze up, and use a mix made for modern cars with aluminum engine components.
I have aluminum manifold, heads and water pump too. I should probably look into that... Can you have too many or do you only need enough to do the job?
I would think if you have too many it would just take longer for the electrolysis to eat them. Each one would be eaten at a slower rate. Might be better if the sacrificial material was spread around the system?
I used a sacrificial anode in my B motor with an aluminum Winfield head and never had any problems but not on my 8BA with Offenhauser aluminum heads, will see how it does. I make sure to use the newer antifreeze for modern engines since most of them have aluminum heads and radiators. I also use copper head gaskets and paint them with aluminum paint before I install them, might be an old wives tale but that's what I was told years ago.
Screw in zinc anodes are also used in some hot water heaters, so should be available at plumbing supply places. Everyone changes those regularly, right?
It should be pointed out that magnesium is the "least noble" metal, and therefore protects better that zinc. Magnesium anodes are available, and they are what I have always used. Check out a galvanic table some time.
I put a Be Cool sacrificial in my aluminum radiator 4 years ago. I have a ground strap on my radiator. So I bought 5 new anodes on Ebay for the price of my OG one. Took out the old one and it looked fine, replaced it anyway. It doesn't have more that 10,000 miles on it.
When I was 15 (1965) my Dad told me to put a zinc in the radiator of my '40 Ford when we installed the aluminum heads. He'd been doing it for years in his cars. I got one that fit in the neck of the radiator from our local auto parts store. That was my one and only flathead. Fast forward to today..... my cars all have aluminum radiators, water pumps, heads, and intake manifolds, I've tried various types of coolants to try to fight corrosion but I totally forgot about the good old zinc trick. Glad I Found this thread.
Thanks Flatheadjohn47 for starting this thread, sorry I didn't mean to steal your thunder. This is a very important thread that almost nobody knows anything about! I even went to several parts stores and a couple of boat shops here on the Gulf coast of FL and most did not know what I was talking about. Shocker! Today, I actually found a West Marine store that had them in stock.