It quite clearly states that motors are not included in the ebay and paypal money back guarantees.
It is up to the buyer to go and check the vehicle over and make sure everything is OK before buying and paying in cash
You should not pay by paypal for a motor it should be cash on collection and inspection
All you can do is to contact Citizens advice for their help to see if there is any action you can take
it is was a private seller then there is nothing you can do
If it is a trader then you may have some rights
