Valve leak

[donaldmk]

I pulled the head today on my 1988 325i because the compression was too low in the number 4 cylinder. (30) I did a water test on all the ports and the number 4 intake valve leaked water. It closes, but not tight enough. I tried cleaning it with brakeclean, but no change. Any suggestions as to what I do next?

[Dave at Pelican Parts]

Valve job time. At the very least time to lap the valves to the seats--but probably better to break the head down and do the job right. Might even be a (slightly?) bent valve.

Does visual inspection of that valve and seat show anything?

--DD

[donaldmk]

Not that I can see. The valve head is discolored as compared to the other valves.

[Dave at Pelican Parts]

Discolored is not a good sign. Try to clean it up (brake cleaner?), but if the metal is actually discolored, the valve is probably burned. At which point, you're back to breaking the head down and checking everything. And at that point, why not do a valve job?

--DD

[mkdonald]

Probably right about the valve job. This is probably a machine shop type service I would imagine. I noticed in different places that the removal of the rockers requires special care. On the E30, it seems to be less troublesome compared to the other engines with compression of the springs. The process describes seems to be rotation and removal when it comes to the rocker arms. Will most machine shops be capable of doing this or will I need to remove them prior to the visit? I don't think I am qualified to lap and seat them. I have another head that I will use to get my car running, but the non-functioning one is nearly brand new. I should probably recondition and then replace at a later date.

[Dave at Pelican Parts]

I don't know if "most" machine shops would be capable, but a decent one that has worked on BMW motors will be.

--DD