Sticky thermostat

[New-B]

Hi all, 

I'm hoping someone might be able to help. Recently had an issue with a large crackling sound under the car's bonnet (no issues picked up on the dashboard), called the breakdown service who weren't able to confirm anything as by the time they'd arrived the sound had gone. They suspected a 'sticky thermometer' and that I should take the car in to a local known garage who are specialists in jag/Land Rover cars (as there had been another issue I had to sort out anyway). 

Ive dropped the car off with them and later received a call to say car is in good nick but they weren't able to replicate the sound and they needed to do more testing which requires the director taking the car home (which is apparently a fair distance) in an attempt to replicate the same issue and it will cost £160 for the road test with no extra charge if they aren't able to sort the problem out then and there (I understand the principal but not the method). This is my first jag bought last year, so I haven't (nor have my family) had any experience with costs etc. I was hoping if someone could shed a bit more light as to whether this seems legitimate. I guess I want to make sure I'm not being ripped off in any way.

Thanks in advance.

[Old Peter]

Trying to replicate the sound can be done by yourself at no cost other than fuel.  As Ron has said "non specific".  

My S Type lost some power 100 yards from home but no warning light. When I got on the drive, I just raided the ticker rev to 2000 rpm - a dull bang and a puff of smoke and all has been well ever since..

If there is nothing apparent under the bonnet and the car drives well, and the garage cannot find anything, I would guess that there is nothing wrong.

Peter.