Valve Job Looming?

[BlackOnBlack]

My 525iM with 220K miles on it started running on 5 cylinders last month after a freeway run down to San Jose. I didn't get the chance to look at it until this weekend. Plug and coil checked out so I went to the compression test.
No compression in #6 cylinder. Adjoining #5 pumps to @ 200 psi after 5 cranks.
There's no back fire through the intake and seemingly no blow-by coming from the crankcase so I'm thinking a bad exhaust valve.
Any ideas on ways to narrow it down definitely?
I'll probably bring it in to my mechanic on Tuesday or Wednesday.
Everything else about the car is good so I want to keep it.
Anybody have an idea what a valve job on these might cost?
Thanks,
Steve

[Grantus]

I have found that a bad exhaust valve can often be heard by listening to the tailpipe at idle.
A regular hollow sound amongst the more regular noise, sounds like pong pong pong.

A leakdown test would tell for certain.

[alex 1993 525i auto]

See that, I have the same issue, it happened to me as well 1.5 months ago, so I'm in the process of removing the cyl. head to get the valve job done in a machine shop. It is in storage for the winter so I do it myself during weekend when I have time to work on it. Have a look at this for the whole story (unfinished):
http://www.bimmernut.com/forum/5-series-bmw/43175-engine-running-rough-shaking-badly-idle-higher-rpm-too-hot-cold.html

I would say it will cost a grand for sure. I'm guessing as a w-e mechanic, 6 hours of work by a pro in a shop for the removal and installation of the head + $300 for the valve job on the cyl. head. Correct me if I'm wrong.

You can try this to test if it is the exhaust valves that are stuck open or broken: I have the same issue on the cyl. 6. with no compression at all. After removing the cyl. head cover and fan clutch, I turned the engine to see the cams and hydraulic cam followers and they looked fine. Then I set cylinder 6 with cam lobes pointing up, which close the valves. I added injector cleaner liquid in the spark plug hole with a funnel and I saw the liquid free flowing down. I did the same test with cyl. no. 2 and the liquid was staying inside for a few minutes. I heard the liquid going down the exhaust when pourring it in the cyl. 6. When I remove the intake manifold there was no injector cleaner in there, only a little bit of oil.

Best luck

[BlackOnBlack]

Thanks guys.
Talked to my mechanic. It'll be about $1600 as long as it's just the valve job.
I don't have the money for it right now. Registration with smog test is due next month. I'll register it as non-op until I can get the cash together for the fix. I'll just work on the little things until then.
Steve