Why copper??

[Tor-King]

I really would like to know WHY Yamaha decided to use only two copper washers on the head installment?  Why not use steel washers like the other 10 mounting hardware?  I have always been perplexed with this.  This is really going to bother me if no one has an answer.

Thanks,
Dean

[Pat Conlon]

Just on the two outside right cylinder studs, to seal the oil passages. All the other studs use the steel washers.
When you torque the head nuts, it squishes the soft copper to form a seal around the cylinder studs.
......kinda like the crush washers on your banjo bolts.

[Urban_Legend]

Copper is usually used in applications where a good seal is needed (eg brake lines) because it is soft and conforms to the shape of the surfaces on either side of it.

Mark

[fj1289]

I really would like to know WHY Yamaha decided to use only two copper washers on the head installment?  Why not use steel washers like the other 10 mounting hardware?  I have always been perplexed with this.  This is really going to bother me if no one has an answer.

Thanks,
Dean

Perfect timing!  http://www.fjowners.com/index.php?topic=15993.msg161183;topicseen#msg161183

[Tor-King]

Thank you.  Now I can sleep knowing why those damned washers are different.  Thanks Chris for sending me that link.  What were the chances that it was recently answered?  Now, back to regular programming.

Dean

[priley88]

Interesting!  Newbie question- should those copper washers be replaced every time the head is removed?
Thanks-Pete

[aviationfred]

IMO, they are inexpensive and under normal conditions, cylinder heads are rarely removed. I would recommend replacing the washers.


Fred

[red]

Interesting!  Newbie question- should those copper washers be replaced every time the head is removed?
Thanks-Pete

Pete,

Once the copper washers are crushed, they can become too thin to make a good seal after that.  Compared to the labor needed to fix a leak, new copper washers are worth every penny.

Cheers,
Red

[Charlie-brm]

. . . copper washers are worth every penny.

Cheers,
Red

Beautiful. I think you just gave me an idea on what to do with my jar of washers - I mean "pennies".

[red]

. . . copper washers are worth every penny.  Cheers,  Red 

Beautiful. I think you just gave me an idea on what to do with my jar of washers - I mean "pennies".

Charlie,

They would need to be very old pennies.  Since about 1983, USA pennies are about solid zinc, just thinly coated with copper.  If you scraped off the copper cladding, you would see shiny silvery zinc in any newer penny.  Not recommended, as a sealing washer.       

Cheers,
Red

[Charlie-brm]

Thanks for bringing that up Red. That didn't even cross my mind, and I used to work for a private mint that competed globally, so my bad. We did away with manufacturing pennies in Canada in 2012.
From 1997 to that point they were like what you said, copper plated, but mostly steel with a bit of zinc. So un-Canadian.

They were composed of 98% copper, 1.75% tin, 0.25% zinc up to 1996, the last year of the FJ's, Coincidence?  

re copper washers, if someone would rather re-use one in a hurry instead of delaying in sourcing suitable washers, they work harden with use and can get brittle, but they can be softened by annealing, but that won't restore the original thickness that might be called for.

[FJ_Hooligan]

On a somewhat related note;

If you're R/Ring the head the manual also recommends replacing the rubber seals between the head and cylinder on these studs

[Shane4371]

Aluminum and steel create electeolisis

[Pat Conlon]

 

[racerrad8]

Aluminum and steel create electeolisis

Electrolysis or galvanic corrosion requires an electrolyte (water/corrosive liquid) which oil is neither.

Galvanic corrosion is caused by self-induced current created by electrical potential of two dissimilar metals in contact with an electrolyte. It can occur when two dissimilar metals (such as copper tube and steel pipe) are connected in the presence of an electrolyte. Fresh potable water is a weak electrolyte.

WHAT IS ELECTROLYSIS?
Electrolysis is the result of electricity flowing through your cooling system and causing an electrochemical charge across the aluminum. This results in rapid corrosion and severe damage to the components in your cooling system including discoloration, pitting, flaking, and pinholes. Most common in late model vehicles, hot rods and street rods, electrolysis will usually occur if there is a defective or missing ground on one of the numerous potential electrical sources.

As Pat has already stated, the two copper washers are installed strictly to seal the oil galley supply to the upper engine.

If electrolysis were an issue on the FJ, they would not use the steel washer on the other ten (10) head nuts.

Randy - RPM