Morris Minor Owners Club

Here's an easy one for someone - is the sump drain plug meant to have a (copper?) washer?

Straight answer - Yes. Pt No: 6K638 (MOSS).
It is the crushable type and should be replaced every time the sum plug is removed.
Phil

As above, but if you don't have one handy, PTFE tape run two or three times around the plug thread will hold it oil-tight indefinitely until you can fit the correct item

Thank you both. I will get one next oil change time

Yes it should have copper washer - again - I've never had to change one and no leaks. Don't overtighten! And NO ptfe tape.... Worry more about the oil filter - make SURE the plate and spring are present and correct under the paper element filter.

All parallel threads require a washer. Most, but not all tapered threads use some form of leak avoidance - hemp, tape or sealant. Non-pressurised tapered thread joints may not need extra help to avoid leakage. Not using the correct washer can lead to loosening of the fitting. Losing your engine oil is not a good idea and not worth risking. Some sump plugs use flat washers which can be re-annealed. I recommend the makers instructions are followed for the particular installation as some plugs have tapered contact faces. Perhaps someone can post the form used in minor engines?

Thank you gentlemen - most illuminating. Here is the plug......... parallel thread: http://www.morrisminorspares.com/engine ... ug-p830320

Later screw on filter heads with the parallel threaded union do not have a washer of any sort fitted under the union head even though both the filter head and the union have machined faces.
I have found that a Dowty washer is a must in this situation.
Phil