windhund116

These washers "crush" a bit because they are made out of soft aluminum alloys. They are not like crush washers on spark plugs. Designed to smoosh to specific point, to help seal the combustion chamber. This is why every new spark plug comes with new washers.

zeroptzero

And $2.00 in your area is closer to $4.00 in my region. The diff. fill bolt washer is twice the price of the other less expensive washers. Given that it is made of copper it begged me to ask the question - Why is the differential fill bolt washer different than all other washers on this car ?

ahrmike

if you really want to save some money but want to swap em out every shot, don't buy from honda - you can source washers pretty much anywhere.

slalom44

My guess would be due to corrosion. The fill bolt may not get soaked on the inside with fluid. Capillary action will usually fill in the voids between the threads of an immersed bolt and coat any crevices on the washer from the inside. But it won't if the bolt stays dry. The bolt is made of steel and the diff is aluminum. Since they're very dissimilar metals, galvanic corrosion will take place where they meet in the presence of moisture and salt. Aluminum is a less noble metal than copper, therefore will result in a larger galvanic potential. That means it is more prone to corrosion under similar conditions than copper.

I'm guessing that some time in Honda's history of making engines they encountered a problem with corrosion on the fill bolt and using a copper washer corrected it.

Soviet

They are supposed to be one-time use. I bought my washers in bulk from HandA for a very reasonable price. I've gotten away with re using washers on my own car but when it comes to customer cars I do it by the book.

riceball777

you are always suppose to change the drain/fill plug washers, but i have probable change my diff fluid over 10 times and i have never change the washer and it never leaks.

zeroptzero

Thanks for this reply, perhaps the diff is more susceptible to corrosion as you say. Thanks

flanders

Should be similar circumstances for the transmission fill bolt though?
And that one uses an aluminum washer.

Slowcrash_101

The transmission has an oil pump, the diff doesn't

carrnut21

I order this kind of stuff from majestic honda, their prices are really good, just order a bunch of stuff you need at once to save on shipping.