Washer sizing & material help

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I've lost the oil drain bolt washer on my Tohatsu 3.5hp outboard. I could do with getting an off the shelf replacement asap rather than wait for the proper Tohatsu replacement. The drain is weeping, as you would expect.
The Tohatsu part is listed at 10.2 mm ISD, 19 mm OSD and 1 mm thickness.
Standard M10 (form A) washer is 10.5 isd, 20 mm osd and 1.5mm thick.
Will this seal the oil drain and is A4 stainless a suitable material for this purpose?
 
Try it and see. Wouldn't think stainless would do any harm. I always carry a pack of mixed size red paper/card washers in the boat for such things - cheap enough. A copper washer would seal better than stainless if you have one.
 
Quiddle said:
I've lost the oil drain bolt washer on my Tohatsu 3.5hp outboard. I could do with getting an off the shelf replacement asap rather than wait for the proper Tohatsu replacement. The drain is weeping, as you would expect.
The Tohatsu part is listed at 10.2 mm ISD, 19 mm OSD and 1 mm thickness.
Standard M10 (form A) washer is 10.5 isd, 20 mm osd and 1.5mm thick.
Will this seal the oil drain and is A4 stainless a suitable material for this purpose?
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You can try, but since SS is not very soft, I'd not hold my breath. Don't know anything about your engine, but annealed copper or brass would be better if it's not underwater. Even a fibre or aluminium washer if it is, or a 10mm dowty washer if you can get one easily.
 
Thanks for replies. Will try copper. I was a bit concerned about dissimilar metals but it will only be in use for a fortnight then I can fit the Tohatsu part.
 
Quiddle said:
Thanks for replies. Will try copper. I was a bit concerned about dissimilar metals but it will only be in use for a fortnight then I can fit the Tohatsu part.
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In an emergency I would use a fibre washer rather that a copper washer. I think a copper washer could still be a bit hard and you really don't want to strip the thread in the hole trying to tighten the drain plug onto a washer that is too hard.

I take it this is the engine oil drain plug on a 4 stroke, not a gearbox oil drain .
 
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I changed the oil in mine today. I am fairly sure the washers in both the drain and the level are fibre, although I didn't check. Definitely do not use stainless steel, much too hard. Copper would be OK but just cutting one from cardboard would be a good temporary measure.

Just read VicS' post. I was assuming gearbox drain.
 
vyv_cox said:
I changed the oil in mine today. I am fairly sure the washers in both the drain and the level are fibre, although I didn't check. Definitely do not use stainless steel, much too hard. Copper would be OK but just cutting one from cardboard would be a good temporary measure.

Just read VicS' post. I was assuming gearbox drain.
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The dimensions quoted match the washer for the engine oil drain plug ...... the gear box drain plugs are smaller.


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Thanks for further info. Is there no issue with heat for a non-metallic washer? The original was definitely a silvery metal. BTW, it is the engine drain, as VicS states.
 
Quiddle said:
Thanks for further info. Is there no issue with heat for a non-metallic washer? The original was definitely a silvery metal. BTW, it is the engine drain, as VicS states.
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The washer will be at the same temperature as the oil, if that is hot enough to burn the washer, you have other more pressing problems.
 
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