Water pump cover fiber gasket
 

I drained the old coolant out of my 2011 ec 300 today, and as I tightend up the drain screw, the little fiber washer on the screw split rendering it useless. I went around town looking for a suitable replacement and found none. So....I just tightend the screw back in without a washer and it seems to be working fine (no leaking). Should this be ok or did I screw up?

If you can't find a fiber washer, can you find an aluminum or copper washer? I know my local hardware store carries those, so I use a small copper sealing washer. If the ID is too small, you can always drill it out.

You can also make one by hammering flat a small piece of copper tubing, drilling a hole, then trimming into an annular shape. Heat the copper, then let it slowly cool. This will anneal the copper, making it soft when you install it, providing for a good seal.

I use nylon washers I get in work, work great. Most consumable hardware like this (orings, etc.) I identify and buy in bulk so I don't get caught like this.

Caution, The screw will protrude into the water pump cavity and interfere with the impeller

I use small copper washers. They seal up nicely. Didn't find any issues with the screw feeding through into impeller. I did however notice that the dealer had used liquid gasket instead of the real one at some point and the impeller has made contact with the cover which has cut into it a bit on one side. Just another thing to be aware of.

I'm like GMP and like generally get more than I need when ordering consumables. I've basically got a full set of gaskets, O rings, wheel bearings, brake pads etc.

I have been to plumbing, hardware, and big box stores like Lowes, and nobody has any copper washers. I ended up buying some plastic ones from the plumbing dept. in Lowes. Hope that works until I can track down copper ones.

Any little washer should work as long as it had the ability to crush in a bit and provide a seal against the threads and the bolt head. I'd say your plastic ones will still be stronger than the stock gasket that they come with. Just replace the washer every time you change the coolant.