So long story short bought a nice 2014 t5 S60 (100k miles) that had known bad compression on cylinder 3 from my friend. I've been looking at it for a little bit trying to be 100% sure what I'm fixing before I just pull it apart. I have NOT had a chance to verify the timing marks yet but have sent a scope down and everything looks "ok" except some excessive build up on the valves (especially cyl 3). Compression test is as follows.
Cyl 1 - 150
Cyl 2 - 90
Cyl 3 - 0
Cyl 4 - 90
Cyl 5 - 150

The only reason I'm even posting this is because I won't get to look at the car for a while but thought those numbers seemed suspicious? Does anyone know these motors well enough to be able to say if the timing belt jumped a tooth or two if that would be possible with the cam setup? No damage to the piston tops, walls look good, adding oil into the cylinder doesn't change compression. Just not sure if I should get my hopes up that it's just the timing. I'm 99% sure this head is coming off no matter what but I just want to be 100%. Tried smoke testing it with mixed results. Without hand cranking and seeing timing marks was never 100% sure if I was on compression stroke for cyl 3. Oh and my kid won't get his license for almost a year so I got time haha. Not exactly my top priority right now but would like to get ahead of it.

Thanks!
Greg

 

It's not a bent valve or timing problem. (unless the previous owner did something trying to fix it after the timing had a problem) Probably a burnt valve with maybe some overheating that happened causing the adjacent cylinders to be low. Either way the head has to come off. Hopefully it's not anything worse like a piston problem! (but that is not a normal failure)

 

The previous owner didn't touch it. I will do a little more testing before I pull it but I'm pretty sure you're correct. I just thought it was odd that the numbers were basically exactly bad LOL. Any advice on getting a rebuilt/reman head? I don't mind bringing it to my local machine shop unless is quicker/easier/cheaper to just do some sort of core swap out.

Thanks!