Earlier somebody suggested that you should avoid that. You can't.
However their sentiment is correct. Tribunal referees are not judges and in most cases not lawyers either. Their decisions seldom follow the rule of law and most often favour the person they see as most 'aggrieved', which is usually the customer or buyer.
Looking at the facts as you've presented them:
We know that you have sold a car stating that the engine had been "rebuilt", which implies some period of reliability.
We know, (assuming the kid is telling the truth), that the motor is buggered.
We don't know how he drove it.
We don't know what fuel he ran it on, (regardless of what he said on the night of purchase).
Not only do we not know these things, I imagine that a competent mechanic acting in support of the kid would be able to convince a referee that neither would have impacted on a properly 'rebuilt' engine.
I don't know how much you sold the car for but if it were a reasonable amount then an element of 'fit for purpose' will come into play in any decision. Most specifically - how long might a buyer reasonably expect a car costing several thousand, or however much it was, to perform reliably and particularly given the enticement to buy of the stated 'rebuilt' engine.
There is nothing in this
which protects you from that.I (persons name) acknowledge that in signing this agreement I understand that I am now responsible for all maintainence and care of this vehicle. I also agree that I have inspected the vehicle and am happy with the condition of it".
There is no certainty. Tribunal referees are individuals and often given to making some outrageous decisions.
However, with considerable experience of this system, I'd suggest that, if it goes to a tribunal, they'll very likely award against you to the tune of at least half the repair bill, probably more.
If it were me, I'd be getting on to the owner and talking to his mechanic to find out exactly what the issue is and attempting a remedy without the tribunal.
If you are selling a vehicle and wish to have no comeback whatsoever you need to be very explicit in your contract which you should have prepared and show to prospective purchasers before they view the car, and have them sign on sale. Most sellers get all excited at the prospect of a sale, oversell the vehicle and then soften the 'no warranty' bit at the end.
This is the sort of thing we'd prepare on the yard for sales outside of the warranty system:
This is a contract for sale of 1987 Toyota Corolla ZXCVBN Vin # 1233456 which is offered for sale on an 'as is where is' basis from premises at 123 High Street, Levin.
The vehicle is sold unwarranted and as parts only and nothing either said or written by the seller is to be considered a statement of any condition or fitness for any use or purpose.
No warranty is expressed or implied.
It is the purchasers responsibility to carry out any inspection, testing or research to satisfy themselves of the vehicles condition and fitness for any purpose they intend. Further it is the purchasers responsibility to remove the vehicle from the place of sale and once having done so all matters pertaining to the vehicle, and it's use, are the sole responsibility of the purchaser.
On signing this contract the purchaser indemnifies the seller from any claim in respect of any matter pertaining to this vehicle from time of sale onward.
That oughta cover you in any similar situation.
