Very low compression in cylinder 2
 

Hi,
I have 30psi of compression in cylinder 2. The remainder of 6 cylinders are all between 160psi-180psi. X5, 2003, 3.0i, 122K miles.

Any advise on what to do next?
Considering AC Delco Fuel Injector and Upper Engine cleaner to soak in the cylinder for 24 hours.

Is there another test I can do to determine if the problem is at the top of the cylinder or bottom?

Could it be the valve cover gasket or is it definitely the head gasket (top) or rings (bottom)?

Thank you very much for your advise as this could very well be a multi-thousand dollar problem.

I would try that first as instructed in this video. GL - https://www.youtube.com/watch?v=_Vo4fm0JDPY

A shop that can perform a leak down test can tell what is the problem.

Do a wet and dry compression test.
You probably have a burned valve, likely exhaust valve.

With only 30 psi you have a pretty significant issue. You need to confirm. Pull all plugs and repeat the compression test. If low as much as you say, then you are facing a rebuild.

Not a valve cover gasket. Not likely a head gasket, although it's possible. Most likely rings or valves. You have to remove the head to see. I'm not sure what it takes to get to the rings, it might require pulling the engine. I'm pretty sure the AWD system to the front wheels will be in the way.

make sure you crank it over with the spark plugs out to clear the fluid out or you could really cause a problem by hydrolocking the engine...

With that significant and isolated a problem, wouldn't a leakdown test of just cylinder #2 be pretty cheap and easy to do, and have a good chance of isolating the problem to valves vs. rings vs. something else? If so, that could let the owner make a better decision before piling too much money into it (e.g., head removal and inspection).

Like, something even as simple as pressurizing the cylinder and listening/feeling for whether the air (a lot of it) is leaking through the intake, exhaust, or crankcase. Again, forget about cylinders 1 and 3-6, just do 2. No need to get accurate percentages or anything. You know there is a big problem in there somewhere, and just need to isolate it.

ouch.

Re burnt exhaust valves...There are many theories but the Volvo forum people think it is from using low octane (87) gasoline.
I can't prove it.
Just a theory.