Any thoughts on this??? I booked my car in for a service (2012 Fiesta Metal, N/A), before the service the car's driveability was completely fine, apart from a flat spot on throttle response on a cold start when driving. During the service, I got a call from the mechanic and he said he changed the plugs and it didn't start smoothly, he replaced plugs again and still had an abnormal start-up. He done a compression test on all cylinders and said 2nd and 3rd cylinders are only at 50% compression rating? ( around 75 psi). He reckons it could be a head gasket fracture or related? I got the car back and still, the performance isn't any different, not misfiring, no blue smoke, or any obvious indication that its gasket related. What could it be?

75 PSI is only just above half of what I would expect to see and, if the gasket has failed between the 2-3 cylinders, it would get worse very quickly and the engine would sound very sick. Then, if its blowing into the water, you will have coolant loss and again fast deterioration in performance, driving with a blowing head gasket can do serious damage to the head and in one case I have seen a crack in the block, blowing super heated gas at high pressure through a small gap will burn metal.

If it has deteriorated slowly I would expect it is high milage wear like valves and cylinders or something from past neglect like lack of oil changes. It must have been pretty sick for them to do a compression check.

Mileage is only 40k? As I say, no obvious indication of low compression in the cylinders?

Performance hasn't changed (apart from the flat spot), coolant and engine temperature isn't rising, no steam, etc. Nothing pointing out gasket problems really..

I get the car serviced and all of the above is replaced as expected in a service, oil, filters and plugs etc. I maintain the vehicle well. Which is why I am confused!

Get another compression test done as soon as pos at another garage and see what results there are, it the same then the head needs to come off for inspection,

Just a thought, is it still under 3 years old. Warranty?

I've not long taken it to a Ford dealer. I have only a few days before the warranty runs out so I have left it with them to investigate.

Hopefully, surely, they will pin point the issue.. So glad it was found out before the warranty expires.

I'll update the result and feedback from Ford. I can't wait to see what comes of it.