Crush Washers Redux: Anneal or Not

[Dr. Strangelove]

A while back, during the semiannual discussion on the adviseability (or not) of re-using the crush washers a side discussion began about the anneal process.

an·neal (-nl)
v. an·nealed, an·neal·ing, an·neals
v.tr.
1. To subject (glass or metal) to a process of heating and slow cooling in order to toughen and reduce brittleness.
2. To strengthen or harden.


It was suggested that by annealing the crush washer its previous "softness" could be achieved and thus the washer would possibly be again the washer it once was.
If life were that simple.

Having access to a digital micrometer caliper, 3 unused crush washers and one used crush washer I decided it was time to get numbers involved.

The OD average of the new, unused crush washers, measured numerous times in both the up/down and right/left diameters was 19.81 mm (range: 19.77 - 19.86 mm)
The OD for the used CW was 19.96 or 0.76% wider

The ID average for the new unused CW's was 16.34 mm (16.32 - 16.35 mm).

The ID for the used CW was 16.26mm or 0.49% narrower.

The thickness for the new unused crush washers was very uniform: all three measured 1.37 mm thick in at least 6 spots each washer.
For the used washer there was variability of thickness from 1.26mm to 1.32 mm. In other words the used CW was, depending on the spot on the used CW anywhere from 3.6 - 8% thinner tahn new.
When I last changed the oil and tightened down the drain plug I most likely did it finger tight + 1/4 turn. There were no leaks.

So, after using the crush washer it becomes flatter, wider in OD and narrower in ID. Probably no real surprise there. It gets squished. And there may still be enough "give" in the metal to perform again as many have reported.

Will annealing restore any dimensions in addition to making the metal softer?

The jury is still out on that one, because this is what happens when you heat the CW over the gas burner on a household cooktop.

And it never turned red or yellow. It only wilted and became most certainly unusable. It must also be noted that the hemostat ( a "plastic" straight one and clicked one click only) made a very significant remarkable dent in the CW. So if you still want to try this I would lay the CW flat in a pan of some sort and NOT hold it with any pinching instrument.

My rec is NOT to attempt to anneal, especially if you do not have another CW available.

John

[marecycling]

Boy! You definitely need a girlfriend!!!!!!!!!

[duke]

Boy! You definitely need a girlfriend!!!!!!!!!

Or maybe he is having too much of his girlfriend/wife???

[duke]

Apologies to both Dr. Strangelove and marecycling ... sorry, could not help it ...

[DJ Downunder]

Well I find all this stuff interesting...doing the experiment and all...I loved science at school.

I get new ones with every new filter..But I just keep using the old one...and I've had no problems..not one drip.

DJ

[Ves]

Geeeeeeessss I can't believe people still have those discussions... In all the years I've owned bikes and cars, and always done my own oil changes, replaced brakes systems, and done anything else where crush washers are use, I have never bought a new washer, and I have never head a leak...

The crush washer is a capitalist pig plot to milk you out of your hard earned money... resist with all your might...

[OU812]

Geeeeeeessss I can't believe people still have those discussions... In all the years I've owned bikes and cars, and always done my own oil changes, replaced brakes systems, and done anything else where crush washers are use, I have never bought a new washer, and I have never head a leak...

The crush washer is a capitalist pig plot to milk you out of your hard earned money... resist with all your might...

I have reused them, no problems.

[SLEDGE]

I've use the same cw for 3years, no leaks.

[machew01]

If the washer is deformed by more than .40125%, by all means, replace it.

mac

[Green Hornet]

You can only anneal COPPER crush washers not aluminum.

Heat them up til red and drop in water. Brush off scale and reuse.

Did this for years on my old triumphs. But now there aluminum cost 36 cents each so guess what. But a bag full and never worry about it.

[R4R&R]

The crush washer is a capitalist pig plot to milk you out of your hard earned money... resist with all your might...

Maybe. My car has an 'O' ring built into the drain plug, and it doesn't ever need to be replaced (until it tears, then I have to buy a whole new plug!).

The crush washers aren't that expensive so I try to rememebr to pickup a few when I have the opportunity.

While I've re-used them (I think all currently on my bike are 'used'), they don't seal as nice as a new one, but no major leaks. They do weep a little, leaving enough oil to pickup dirt and show that it's weeping.

[mcollect]

Let me explain annealing. I have a lot of experience in metalsmithing. Copper is annealed by heating to red heat then quenching in water, it is then dead soft, it melts at 1083 C. Aluminum is heated to a much lower temp as it melts at around 450 to 500C. To keep aluminum from melting it is rubbed with soap and GENTLY heated only until the soap has turned black then allowed to air cool. Each metal has its own temp and type of cooling in order to anneal properly. That said, I use the CR a few times and throw them out when they are tight on the plug, figuring they are then work hardened.

[yjleesvrr]

I've reused crush washers many times with no problems. I've even foregone the use of crush washers with no problems.

We seem to be getting extremely anal here...

[Dr. Strangelove]

Boy! You definitely need a girlfriend!!!!!!!!!

That is what I keep telling my wife! At last, a reputable member of society agrees with me!

I think crush washers are the issue they are because:
-they are a trivial, but necessary piece of hardware.
-we sometimes change our oil at a moment's notice and do not have the organizational skills to have one before-hand
-BMW dealers are few and far between for many, many riders (mine is 80 miles away)
-BMW riders think of themselves as individuals and "can-do" types and are reluctant to pay the sodomy tax that frequently accompanies the purchase of OEM parts
-and many need a girlfriend or a wife or at least something more romantic/softer than a torque wrench (although there is a long standing thread in the "male only" section of the website, that "good" women have a range of nM from 0 to only about 20 nM--so not a whole lot of resistance before they click).

Hope this helps.

John

[NCPadgett]

One question - if new CWs come with your filter, and you reuse the old one, what do you do with the new CW? IMO if I have to throw one away its a no brainer - the old one. But my wife says I'm not that smart so you probably shouldn't listen to me Be safe.

[Dr. Strangelove]

Hi, NCPadgett

At least for me the reuse of CW issue is solely based on lack of easy availability of replacements. New filters, esp if someone uses an alternative filter, do not/may not come with a new CW. From some suppliers it is a separate charge item.

If I have a new one, I will use it.

John

[CycleRob]

OK. I admit that I've been bad, when it comes to working on my own bike(s). I've re-used the BMW washers many times, even when new ones are 50 steps away in the basement. Never get a drip or even a telltale dirt collecting weep, so the habit continues. Yes the oil filter comes with a taped-on washer, but the trans and FD mean re-use or buy new.

There are key points to observe if you want to or need to re-use a crush washer. If you clean, inspect & maintain the same previous mating surfaces while only approaching the point of permanent deformation . . . . you can re-use the washers for years. As you tighten the drain/fill bolt it first contacts the washer, then quickly begins compressing it. It's a very narrow zone where you are just compressing it like a spring, where it will still return to it's previous thickness if you back it off. If you continue going tighter you will get permanent deformation beyond a barely perceptable point in the tightening rotation. Then your washer gets thinner and larger in diameter. Go too too far too many times and it may crack/crumble/split and then you've got a dripper loosing new oil.

Inspect it for cracks or splits, clean it with an airblast or carb-cleaner spray, don't over torque it. Use it again . . . . up to 3 or 4 times. Too often it's not just being cheap. It's mostly lazy or lack of a new one. Now you know another little gem that can save the day if you didn't plan ahead - - - again.