[Gregory_K]

galvanic reaction, spark plug to block

My 05 DC Tacoma V6 4.0 is 10k overdue for spark plugs.

Question on galvanic reaction.

The block is made from Al the plugs some form of steel. Most anti-seize contains graphite (bad for Al).

Am I looking to much into this subject on the use of antiseize on the plugs and block to prevent galvanic reaction.

I have Zinc antiseize on order and both C5-A and High temp Nickle based instock at the house.

Loctite lists a recomendation of what type of anti-seize to use for the materials your using. Zinc is listed as a best choice for Al threads. Only problem (if it is one) 700 deg F max temp.

 

[Gregory_K]

Found my Answer.

From Wikipedia

"This effect can be prevented by electrical insulation of the materials, e.g. by using rubber or plastic sleeves or washers, keeping the parts dry so there is no electrolyte to form the cell, or keeping the size of the less-noble material significantly larger than the more noble ones (e.g. stainless-steel bolts in an aluminum block won't cause corrosion, but aluminum rivets on stainless steel sheet would rapidly corrode.)"

 

[tempetom]

I don't think spark plugs would work if they were insulated from the block. I've also never seen any corrosion from aluminum rivets on stainless steel. I do know that Magnesium is pretty much allergic to most other metals. I hope one of the auto mech guys can throw some light on antiseize compounds for spark plugs, but I've never heard of any being used.

 

[cookiemech]

I've removed several sets of (original) plugs from Toyota V-6s and V-8s at 90K plus miles without incident. I replaced all of them with OEM-type plugs (NGK or Denso), using a very slight smear of the silver anti-seize paste (Permatex) on the threads, then torquing the plugs on the low side of factory recommendation (since the anti-seize acts as a lubricant). My technique is based on experience with BMW motorcycles, which also have aluminum heads, and the subject has been beaten to death on those forums.

I've never had a problem with any motorcycle or car I've serviced this way; the only time I've ever had to repair a cylinder head was on someone else's Kawasaki motorcycle where they had used a Champion plug and probably overtorqued it. (I never use Champion plugs in aluminum heads, only in cast iron heads where the Champion plug was original equipment, like old lawn mowers.)

 

[Dave_In_WPB]

I may be mistaken...but aren’t the threads of a spark plug stainless steel?
If they are, and considering the seal provided by the grommet on the coil pack, galvanic corrosion should not occur.
I could see this as an issue if you were constantly blasting your engine with a pressure washer and had no seal on the spark plug chamber, but that area should remain bone dry.

I'd lean toward giving the Toyota engineers the credit due, and feel good assuming they have considered and researched the use and potential problems of dissimilar metals.
I just can’t see them designing such advanced engines to overlook or ignore any detail that may discredit their reputation for very well thought out power plants, especially something as simple as corroding spark plugs.

No moisture, anti seize compound, and a quality plug you should be fine.

If I am incorrect, be assured one of our esteemed members will promptly provide a more appropriate response.

I'd say search some of the shimmy...I mean Chevy forums for issues with the corvette, or some other maker who has used aluminum heads for several years.