Copper Washers For Sump Plugs

[Pedro's Pajero]

Has anyone had negative experiences with using copper washers for sump plugs?

I replaced my engine oil sump plug washer with a copper one a year ago, and have done several oil changes, never had any leaks.

I'm now looking at the original auto transmission sump plug on my 2004 Diesel Pajero, and it appears to be aluminium, and is showing signs of wear, so I'm about to replace it with a copper one, but thought Id check here if anyone had replaced this particular washer, and if so what did they use, and has it leaked at all.

Thanks

Pedro

[old Jack]

The engine sump is steel, the engine sump plug is steel so using either a copper or an aluminium crush washer is ok.
The gearbox and transfer case are made from alumium alloy, the filler/drain plugs are made from steel so it is best to use a alumium crush washer to prevent galvanic corrosion due to incompatible dissimilar metals.

OJ.

[Pedro's Pajero]

The engine sump is steel, the engine sump plug is steel so using either a copper or an aluminium crush washer is ok.
The gearbox and transfer case are made from alumium alloy, the filler/drain plugs are made from steel so it is best to use a alumium crush washer to prevent galvanic corrosion due to incompatible dissimilar metals.

OJ.

That’s a great point, the transmission body is a aluminium part, but the sump/pan I’m fairly sure is steel. I suppose Isolation between these parts would be provided by the RVT seal or gasget between them.

Apparently copper and aluminium are reactive and it is not recommended that they are in direct contact, but in this case I am sure the trans pan is steel so I’m not sure if it would be something to worry about.

Can anyone verify that the auto trans sump pan is made from steel?

Thanks
Pedro

[Pixie_au]

Put a magnet on it?

[erad]

Galvanic corrosion requires dissimilar metals as well as an electrolyte to carry the galvanic current. Water is a good electrolyte, especially sea water, but oil is not. Using copper washers on aluminium casings should be OK - as long as the plug is not exposed to water. Oil is more of an insulating medium so it would not assist in corrosion.

[old Jack]

Galvanic corrosion requires dissimilar metals as well as an electrolyte to carry the galvanic current. Water is a good electrolyte, especially sea water, but oil is not. Using copper washers on aluminium casings should be OK - as long as the plug is not exposed to water. Oil is more of an insulating medium so it would not assist in corrosion.

4wd driveline has water exposure and mud (dirt + water) contamination. Water will dry off quickly so it is not so much an issue unless you operate in very wet conditions continually but mud carried a whole lot of substances that can be highly corrosive either acidic or alkaline. Mud that gets inside chassis rails and is not washed out correctly ends up corroding the chassis from the inside to the outside. Also not helping is cars use the metal body return and although the engine and transmissions are rubber mounted they also have earthing straps to the body.

OJ.

[pharb]

Wow. I never realised what a science drain plug washers were!!

The only times I have regularly replaced washers on drain plugs (or filler plugs) was on some heavy earthmoving gear or trucks that utilise rubber O rings in O ring grooves, and then only when they are heat effected, aged and have lost there elasticity.

Have replaced a very small number of metal ones, but very rarely. Except for our Ford Laser which always weeped regardless of aluminum, copper or fibre, but after nearly 400,000km the amount of oil weeping from sump plug didn't matter compared to the amount that was dragged past valve stem seals

Thats the only one of my own vehicles I've ever replaced washers on, and the only one that leaks.

However when I did work experience at a Nissan dealer back in the late '80s every service recieved new plug washers.

Can't leave to much money in the customers pocket

[sharkcaver]

Been using ali crush washers for years now on 2 paj's. Be buggered paying $1.50 or whatever they are now for oem single use washers. The one ali washer will last numerous changes before showing signs of leakage.

For example:

https://www.ebay.com.au/itm/15-x-HONDA-MAZDA-HYUNDAI-many-others-14mm-aluminium-Sump-Plug-Washer/163168330917?hash=item25fd9724a5:g:gZMAAOSwhQhYzMd8&frcectupt=true

[koshari]

Galvanic corrosion requires dissimilar metals as well as an electrolyte to carry the galvanic current. Water is a good electrolyte, especially sea water, but oil is not. Using copper washers on aluminium casings should be OK - as long as the plug is not exposed to water. Oil is more of an insulating medium so it would not assist in corrosion.

My klr comes factory with copper crush washers on the banjo bolt that attaches the steed upper cylinder lubrication pipe to the aluminium head, kawasaki generally know what thet are doing so i would agree with your thesis.

[Lance]

Wow.

However when I did work experience at a Nissan dealer back in the late '80s every service recieved new plug washers.

Can't leave to much money in the customers pocket

11026-61000 genuine Datsun/Nissan copper crush washers, I sold a gazillion ovem over the years.....

[pharb]

11026-61000 genuine Datsun/Nissan copper crush washers, I sold a gazillion ovem over the years.....

They must of been a very poor quality item if they needed replacing so often

[stumagoo]

Some older cars had a little tab on the surface of the sumps where the plug seals. these tabs would leave a small dent on the crush washer which then would leak if reused. It meant many 80's or so cars needed a new copper washer with every oil change

[Pedro's Pajero]

The Last time I serviced the transmission on my Pajero there was a slight oil weep from the sump plug, I remember having to tighten it up with a bit of extra force to stop the leak, it’s been fine since then, but now that I was dumping the oil in the pan again I was not going to re-use the old washer.
I’ll keep an eye on it but I’m happy to say I’ve now installed a copper washer and it hasn’t leaked at all, and extra torque on the bolt was not required.

[benckj]

Something which hasn't been mentioned is why copper or alloy washers are used to seal between two metal surfaces. The two alloys used are soft and can form to the parent surfaces much like a gasket. They work harden over temp cycles and become brittle which is why stress cracks can be seen in old washers. This is especially true with alloy crush washers that have been over tightened. They also do not re-seal if used again as they are harden and not forming correctly when torqued against an uneven surface defect.

Another modern alternative that I've used with great success is a Dowty washer. These incorporate an internal rubber lip which forms the seal rather than soft alloy being pressed between two surfaces. Just need to make sure the correct size is used and there is enough contact area for rubber to seal against. No problem using this type again!

[disco stu]

You know, if someone started a thread titled "lets talk about electronegative metals, galvanic corrosion and work hardening of metals" no one would be interested. But one mention of sump plugs and.....