galvanic corrosion / stainless steel washers ??

[3046moparcoupe]

About 3 years back, after seeing a brand new stainless bolt and nut, gall together immediately after the nut was just hand tightened down,...I decided I'd not use any stainless steel bolts or nuts on my project. 

I suppose the answer to this for folks who have/do use stainless steel hardware is to use anti seize on everything,..(which if the anti seize remains over the course of things, I suppose is a perfectly good way to go)..

My choice at the time, was to go with either chrome nuts and bolts ( for the smaller stuff 1/4" 5/16" etc),...and grade 8 steel bolts and or original steel nuts (for the larger 3/8" and so on).

I DID HOWEVER USE STAINLESS STEEL WASHERS PRETTY MUCH ACROSS THE BOARD, as they were cheaper and I had it in my mind that they wouldn't be having their cad or zinc plating scratched off when assembled and begin rusting....

Now, I'm wondering about galvanic corrosion possibilities....??

Anyone out there have any experience with using stainless steel washers around these old cast iron and steel parts ??

thanks for the help...

Steve

[fhubler]

Steve, the short answer is "yes".  If you want the long answer, go to this link: http://www.corrosion-doctors.org/Definitions/galvanic-series.htm

Keep in mind that galvanic corrosion is an electrochemical  cell that requires four components to function: Anode, Cathode, Metallic Path, Electrolyte (A.C.M.E. like in the old Road Runner cartoons).  Corrosion cells exist even on the surface of the same metalic substrate any place there are dissimilarities, such as mechanical stresses, differences in grain structures, differences in electrical resistivity of the electrolyte in contact with the substrate due to various factors, etc.  Corrosion stops when one of the parts of the corrosion cell are taken away.  Anything that insulates one dissimilar metal from another will help (this takes away the "metallic path" from the electrochemical cell).  Keeping the metals out of an electrolyte (any moisture bearing medium capable of conducting electrical current) will stop galvanic corrosion as well.  Now, if you're still having trouble falling asleep, I'll keep explaining... only kidding!  Hope this helps.

 

[Plymouthy Adams]

as I said before it is only a miracle these cars have survive 70-80 years that they have.......

[DrDoctor]

Steve,

   I’ve had nothing but trouble with stainless steel fasteners. I used to ride a chopper—over 9’ long, and I used chrome-plated hardware on it exclusively. I never encountered any problems with them. I was told by an experienced biker to avoid stainless fasteners, since practically everything on a chopper is in the open. So, after that, I do like you do—chrome, or grade-8 fasteners.

   Further, fhubler is correct on all counts. The example I’m aware of the dissimilar metals issue is using a brass fitting between a copper pipe, and a galvanized one. I’ve also experienced a late-model Cadillac (mine, of course) having its head gaskets deteriorate due to the combination of cast iron block, aluminum heads and intake, and using the wrong anti-freeze, and even worse—not changing it. To put it mildly, it was an expensive lesson, and a very inconvenient one, too. So, been there—done that. I guess some things I have to learn the hard way.

[fhubler]

The farther apart two metals are in the galvanic series, the higher the electrical potential between them in an electrolyte.  If you put an aluminum head on a CI block and have ANY metallic path between the two, as soon as you fill it with coolant you have an electrolyte.  You just installed a very expensive anode on your engine block.  I'm not a chemist, but I would bet the "special" antifreeze is designed to prevent, or at least slow down ion transfer between the two metals in the coolant (electrons take the metallic path & ions take the electrolytic path).  Remember the old Ford 3.8L V6?  It was bulletproof until they started building them with aluminum heads.  I remember seeing a stack of failed head gaskets 3" thick hanging in a Ford dealer mechanic's bay back in the day when they were doing them under warranty.

[3046moparcoupe]

Great reply's back from everyone, I appreciate it very much...probably the only place I have an electrolyte in place 100% of the time on my car, would be the water pump bolts,...however I used them (only the ss lock washers and flat washers) pretty much every where else on the car,...so I've got a steel or cast iron part, with a stainless lock washer inserted in between a grade 8 or chrome bolt...

In theory, everything in place  - but - the electrolyte,...except when exposed to rain water coming up off the road,....which should be only on a rare occasion as this isn't my daily driver and I wouldn't ever drive it in the rain on purpose...and I wouldn't think my washing the car in the future would be getting these surface areas wet.

the humidity here averages around 40% and higher throughout the year though,...so in my peanut head - that's pretty much my full time  electrolyte exposure,...

I specifically chose AN type washers (small OD)., so I'm looking at humidity exposure pretty much on the outside edges only of those washers,.....hmmmmm ??  

Thank you Tim for speaking with me over the phone about this...

no matter where ya go - there ya are

S.

[Silverdome]

So what are the suggested gaskets and fasteners for an aluminum head and intake on the flat head sixes?

[Andydodge]

When I had the Edgy head Earl Edgerton advised to use a steel not copper head gasket..........I contacted Best Gasket in the US and they were happy to make a steel head gasket for thier gasket set, I also intended to use & had purchased ARP head studs, washers and nuts........unfortunately I sold the car & engine before using these parts so can't give any more info but expected no issues.......I also intended to use some spray on gasket sealer.....Hylomar?..............hope this helps..........andyd      

[fhubler]

I am not a chemist or an engine builder, but I would guess that using the correct antifreeze in a mixed metal engine would be critical, and I would think that the purpose of such a coolant would be to reduce/arrest ion flow between the two metals.  This is just from the standpoint of cathodic protection in the field of corrosion control.  With my limited knowledge of engine building, it seems that mixing metals creates more problems then it solves due to galvanic corrosion, different expansion rates, etc.

[Don Coatney]

Having worked in the food industry for a lot of years I have learned that stainless threaded fasteners frequently gall when connecting stainless to stainless. Stainless to non stainless rarely galls.

[DrDoctor]

   I you’re correct about the differences in antifreeze. That was a very expensive lesson that I learned the hard way. I’ve been more careful since then, and I have the coolant changed semi-regularly on our current Cadillac (it doesn’t have a petcock on the radiator, there’s no fitting in any of the lines, and no room under the hood . . .).

  I do remember the Ford V-6 issue. My parents had a Ford with that engine, and the dealer replaced one (yep, one) head gasket, and when they brought the car out front for them to take it home, the other one began leaking. Hard to believe, but since I took them to get their car, I couldn’t believe what I was seeing. Only in cartoons, or so I tho’t.

   Best regards to all herein . . .

[wayfarer]

18 hours ago, Don Coatney said:

Having worked in the food industry for a lot of years I have learned that stainless threaded fasteners frequently gall when connecting stainless to stainless. Stainless to non stainless rarely galls.

I agree,  it would appear that the SS threads are  'soft' enough to move around under pressure and try to meld together. I use Never-sieze on just about everything and I like to use Everdur nuts on SS bolts.