This is a cautionary tale and an ask for advice
2017 I bought a used 2012 C30 T5 Premier stick, 110k km, and immediately the lemon problems started. It came from Quebec which apparently with their salty winters is a red flag!
First, somebody power washed the engine bay and a month later, moisture in ECM caused limp mode. Tried driving to dealer, stalled out on a hill, hero in truck cracked the read bumper pushing me out of the way.
Then, leaking sunroof drains - not clogged but completely pulled out, (probably was like that when I bought it, but mostly garaged so didn't notice until way too late) slowly building up 2 gals of water underneath both waterproof mats. After two months of drying out in winter, started it with the seat disconnected and this shuts off the whole airbag system. Needed a dealer reset.
Finally, it suffered 1 second of engine overheat, which apparently is enough, and 2000km later the engine is toast.
In total I put only 8k km on the car in a year!
When I got it, it had a small crack in the coolant reservoir which I stupidly ignored. However, it was safetied in that condition, and Volvo dealer didn't mention it when diagnosing the ECM problem. Also, the reservoir is multi-chambered, so it can look almost full from the front but be dry in the back. And unforgivably, P1's don't have a low coolant sensor. (but they have a low windshield fluid sensor, Volvo priorities...)
In retrospect it was slowly boiling off coolant, and over a couple of tanks in the summer it was heating up to operating temp more quickly and after shut off it would make a subtle ticking sound for a few seconds like boiling water. Because it was. But I was distracted by other personal issues and wasn't thinking straight (also having owned Toyotas and Hondas which can't be killed)
After a coolant flush everything was ok for 1000 km then it started running rough at start up for a few seconds and white exhaust, coolant level dropping. Oil has never fouled except the oil trap collected yellow goop and clogged giving the evil howling sound (diaphragm was fine). I replaced this (access was brutal, yfkmr?), fixed the howling problem, but just before putting it up on blocks it gave a "reduced engine performance" warning and since then runs poorly with very low power, can hardly get up a small hill. I had hoped the oil trap replacement would fix that but it's a separate problem. Probably due to oil sludge somewhere it shouldn't be.
So I have a lovely shell of a car with a dead engine.
Currently it's a third car which we don't really need. I replaced it with a 2011 C30 which is in much better shape underneath, gets about 10-20% better mileage, but is subtly worse re noise, stereo quality, throttle response and acceleration, ie less fun to drive. I really like the 2012 more. And yes, I'm like the princess sensitive to peas. I've never really been into cars until driving a C30, it's just perfect for ride handling balance, a refined daily driver that was also a blast on the back roads.
Question, scrap it (at 1/10 of previous value), head job or replace the whole engine? Both the local dealership and private volvo mechanic seem reluctant to do anything, which I gather is due mostly to the difficulty of working in the P1 engine bay. Also used engines are about C$3k not counting about the same in labour at minimum from what I gather. Which is almost the price of a used C30 in that MY.
And I can find absolutely nothing online about anyone having done a P1 engine overhaul.
Any two cents of diagnosis or advice is appreciated.
2012 C30 T5 Premier Manual, Black (life support)
2011 C30 T5 L2 Manual, Silver, (the replacement, yes I did that)