Crush Washers

Technical Area Routine Servicing
2

I am in the process of changing the gearbox and Diff oils.  

Is there a reason why the drain plug crush washers on each are of Aluminium.  The filler washers are of Copper.  

Is there a reason why I cannot use new copper crush washers for the drain plugs ?

JP>

3

It’s a question I’ve asked myself many times, I’m sure all copper or all aluminium washers all round will be fine.

4

It is acceptable to have copper and aluminium together in an indoor situation. In an outdoor situation where there is water, temperature differences etc, it is considered they may be corrosion problems due to galvanic corrosion. Is the diff cover aluminium I know some of the diff casing not the gears is aluminium.

http://en.wikipedia.org/wiki/Galvanic_corrosion#Galvanic_series

I also note that some car manufacturers these days supply aluminum crush washers for sumps including Suzuki but I have just changed our Suzuki Jeep sump, it was steel and has rusted through due to salt on the roads.

5

Later model MX-5 have an aluminium washer on the drain plug and a copper washer on the filler plug of the diff’s aluminium housing…

6

So either Mazda are having problems deciding or they cannot make up their mid.

I have just bought around 100 copper washers of various sizes for different car oil changes and wonder if I should also buy some aluminium ones.

7

One theory I have us the presence of the magnet on the drain plug, maybe that has an adverse effect on a copper washer… But why not just use aluminium on both…

8

It is just what is cheapest at the time. I expect Aluminium washers are cheaper than Copper ones.

I seriously wouldn’t worry about galvanic corrosion unless you were going under the sea for 6 months. There are copper ones on your brake banjos.

Al is currently $1,677 per tonne on the London metal exchange

Cu is $7,199

If you buy enough, you would be fitting Al ones!

9

I’d use aluminium, it’s lighter…

10

I’ve used both on my sump plug.  The copper washers are softer than the aluminium ones.  So it’s much easier to get a used ally washer off a sump plug than it is to remove the old copper one. Personally, I’d use whichever you have to hand, but if you’re buying some (a) buy a bulk pack and split it among friends & (b) don’t buy them individually from your Mazda dealer. 

 

 

11

Thanks for all of your replies.  Didnt expect quite so many.  

Have now gone for all copper for simplicity of purchase - local agricultural dealer.

JP>