Shooshing/metallic oscillating sound? M50- please read

[EricV]

Hi all. I know, I know...playing "name that sound" can be insanely annoying....please bear w/ me- I simply wish to have some clue or ideas so I don't go into the shop totally scratching my head. :D

'93 525 @ 116K, M50 Vanos. Just had a good check up a couple of months ago as I'd overheated it and feared I'd warped my head. All tests (comp., cooling system pressurization, exhaust gasses, etc.) checked out good- whew.

I listen to this engine every night before I shut down- I know the sound like my own heartbeat. Well, towards the end of last week, and all of a sudden, I hear a distinct (and very clear...fairly loud) shooshing in the top towards the rear of the engine...sounds as though it's under the top cover of the engine. Sounds like a metallic oscillating sound, rythmic and prominent. I first thought it was a pulley or a bearing of one of the belt driven units- it has that sound. I've listened at the front, but it really, really seems to be from the top rear.
It borders on something more of a paint shaker-ish sound, though it lacks that level of violence (more of a smoother sound.) Again, it just appeared one day.

Car runs smooth and strong...no other symptoms.

Any thoughts or clues on what it may be or where to start?

Thanks guys, I really appreciate your time as always.

Eric

[russiankid]

Could be a lifter or an exhaust leak. Loose spark plugs can also create noises.

[EricV]

Thanks fella. I plan to pull the cover off and start poking around tomorrow after work.

If anyone else has any suggestions please let me know.

Thanks all-

Eric

[632 Regal]

check for oil starvation while in there and also the cam lobes, hopefully it's something simple.

[whiskychaser]

Add timing chains to the list

[e34.535i.sport]

check for oil starvation while in there...

Can I ask how you would check for this? I hope that's not a stupid question! :p what syptoms would there be generally? The reason I ask is that last time I adjuted the valves I tightened one of the Banjo bolts up after hearing how they can become loose, and fear I've tightened it too much. It's been playing on my mind ever since but it's probably fine...

[EricV]

Oh boy..it's becoming evident that I'm out of my league in checking these things out...not even sure where to start on how to check the timing chains, checking for oil starvation, cam lobes, etc. :) Sounds as though it may indeed be major though.

It also sounds as though I may be approaching an "oh sh*t...told myself so" moment in that I've sunk tons of money into this car over the past 6-8 months (transmission was the main thing) and since waffled on "perhaps I should sell it now, before something else major gives up the ghost." I hope I haven't lost the gamble. If I get through this, this thing is outta my driveway just as fast as I can move it. It's been babied and very well maintained, but at 116K it sounds as though it's rapidly approaching end of life issues (in terms of cost/benefit ratio, that is...which is sad.)

Thanks all. I'll pull the cover this evening, read up in my Bentley manual, and perhaps get it over to the shop as soon as I can to see what I'm looking at.

[whiskychaser]

Can I ask how you would check for this? I hope that's not a stupid question! :p what syptoms would there be generally? The reason I ask is that last time I adjuted the valves I tightened one of the Banjo bolts up after hearing how they can become loose, and fear I've tightened it too much. It's been playing on my mind ever since but it's probably fine...

On yours there will be a spray bar that dumps oil on the cam lobes. If you dont mind getting wet you could fire it up with the top off and check it:D But you can get oil up there by turning the motor over by hand. What you are looking for is all the lobes are wet with oil, not pitted or marked or a funny colour. One that has run dry will stick out a mile. The long chain on the M50 is the one to watch. I'm not posting the nice pic of my bent valves or our friend is going to have a heart attack. I think there is a procedure for checking it in Bentleys anyway.

[russiankid]

From what I know, you check the tension on the chain. Make sure its tight on both sides, that it does not move on the cam sprocket, and that it is not damaged in any way.

[EricV]

I'm not posting the nice pic of my bent valves or our friend is going to have a heart attack.

Well done...that was good...had to acknowledge that. :) It'll be touch and go but I'll make it. Thanks for shedding more light on what to look for/at.

Bad storms here tonight, so hoping to start poking around tomorrow.

Thanks all-

[e34.535i.sport]

On yours there will be a spray bar that dumps oil on the cam lobes. If you dont mind getting wet you could fire it up with the top off and check it:D

I'll get the umbrella.

[EricV]

Thanks Fella!