Coolant leak md22l, Bavaria Ocean

[Jam]

Hi
Noticed that plastic reservoir is empty but on unscrewing coolant cap on engine it is full.   Any ideas, all was fine during last season whilst boat was running.  It's on the hard presently and there is a small puddle on coolant under engine.  I feel it's something do do with the coolant overflow on the cap.  Pipes all appear is good condition.  On all other boats I've had reservoir remained full over winter.  There a link on net with some with similar issues but there was no further info as why
Anyone had similar issues, still to go back down and refill, check pipes properly and run.
Thanks
John

[IslandAlchemy]

Inside the coolant tank cap is a rubber seal.  Replace it (costs about £4).

[Salty]

Inside the coolant tank cap is a rubber seal.  Replace it (costs about £4).

👍

[geoff]

If like mine your md22l has never had its fresh water pump replaced it may well be the gland in the shaft. I have just had this problem and appear to have fixed it with a product designed for such a problem in cars[ K seal] I have used it with success in vintage cars and early indications are that it works on boats. Geoff