Soft "whining" sound coming from timing case - M30

[strad]

As near as I can tell using my stethoscope (which wasn't very expensive and probably not the best thing out there) the noise is not coming from an accessory. and it is not coming from the water pump. I can hear it clearly if I put the steth on the retaining cap for the timing chain tensioner, and less clearly if I put it on the head between the vc and the distributor. I removed the valve cover and looked down the timing case as far as I could see and I did not see any broken guides or anything wrong with the chain. Chain appears to be tensioned properly.

The noise is a newcomer -- I've had the car for 30k miles and I'd say the noise showed up within the last few k miles. It probably is a little louder when the engine is cold, but is still present when at operating temp.

I checked the oil pressure using my gauge (plugged into the oil pressure switch port) and I have 30+ psi on the guage with engine warm, although that means oil is probably warm not hot and thus at a higher pressure. I'm running 10W40 in it.

I guess one of the things I'm wondering is what kind of abnormal noises the oil pump would make if it was about to cause problems. I've heard chain slap (on my M42 before I changed the tensioner) and this is nothing like that. It's almost like the sound a supercharger would make but a whole lot softer, and the noise is not apparent off idle.

edit: I would record it for you but the noise is soft enough that I have low confidence that a recording would pick it up properly. 2nd edit: engine has 156k miles on it -- all original afaik.

[GIANUCCI E30]

I know what your talking about. Mine does it. But goes away once warm. I alway chalked it off as the car being cold due to being cold here.I haven't noticed it lately but I'm eager to find the solution.

So I'm subscribed on this.

[TSMacNeil]

Hey guys
I'm about to get on a plane so I don't have much time. I can tell you that the M30 oil pumps are pretty robust. About the only time I hear about failures is when a lowered car rips his oil pan apart and damages the pump in the process. So, I wouldn't worry about the oil pump. My hunch is just tensioner noise, but I'll have to think about it on the plane. The pumps don't have the mounting bolt issues the later engines do either.
Gotta run



EDIT- you might try this: pull the valve cover again and pour some oil down into the reservoir for the tensioner piston in the lower timing cover. Get a long screwdriver or equivalent and exercise the piston back and forth on the tensioner to pull oil in behind the piston. See if it quiets down. If the tensioner is failing, you want to replace it before it grenades and takes the chain out.

Before I forget. M30's are happiest with 20/50 oil.

I'll check in tomorrow after I think on this

[m60b30530i]

I run 15 40 diesel oil in my m30, are you able to hear the noise from inside the car ?

[strad]

Yeah normally I run 20W50 in summer and 10W40 in winter in my SOHC bimmers. The noise is not apparent inside the car unless I unroll the windows, and like I said it gets softer as the car warms up, though it never completely disappears.

[GIANUCCI E30]

This...

I found the source of my whining noise. A worn out hose that goes from the intake manifold to the breather hose on the valve cover.

Once I replaced it the whining stops almost immediately.

[BavarianFanatic]

The timing chain guides bake and become brittle over time. They get a bit whiney when this happens.

[Moeman10]

Holy bump!


Ok, so I’m experiencing a faint whine, almost supercharger soundey, we just did the timing chain job, and a head rebuild. Could the whine just be from a vacuum leak we haven’t addressed yet? It’s intermittent, and happens most often when cold.

Engine is an M30b34 running motronic 1.3

[ross1]

If it's a vacuum leak noise like gianuccie30's was it ought to quit the moment you crack the throttle open as vacuum drops to nil.
good luck

[Moeman10]

It’s definitely not vacuum related we’ve ruled that out now. If i drive down a bumpy road the whine shows up, but is not there unless provoked, wouldn’t that lead me to some rotational accessory, probably in the belt system somewhere? I can get a stethoscope to it next week to pinpoint where it’s coming from. It seems to stay away until jarred into noisiness.

[moroza]

You can remove all drive belts and operate the car (briefly, that is, <5 minutes and gently) to see if anything changes.

[zubbie]

My A/C compressor whines like a cheap turbo

[dschneider]

I have experience with M30 whines. Here's my (not expert) checklist/diagnostic for bad RPM-dependent whine:

First whine: improperly installed aftermarket head unit. Diagnostic: toggle radio/head unit power. Depending on how much your stereo has been mucked with you may have to pull the amplifier fuse (if they have not properly adapted the amplifier power circuit and maybe wired it on).

Second whine: A/C compressor pump. Diagnostic: toggle A/C. May be accompanied by squeal under rapid rising RPM, if the belt is old/loose and/or the compressor is near end of life.

Third whine: much softer than the rest. Most notable under rev/blip from 2200–2500. Present when cold and fully warmed. Present before and after fresh oil change. Not linked to idle throw out bearing (it happens in gear as well neutral, clutch in and out). It's definitely not just the transmission or diff whine (presence in neutral/when stopped confirms this). It's also not either of the previous two. It's audible from the cabin, and not obvious at idle from outside or with the hood open. The rest of the usual engine noise seems to cover it.

So yeah, anyone with answers to the third whine, I'm all ears.

[Moeman10]

Is the third whine almost more of a whistling?

I toggled the AC when the whine was there and it definitely didn’t change, im fairly sure that accessory definitely needs attention though as I’m getting a whistle/ squeal similar to the third noise. It’s been sub 20F all week and the the whine hasn’t been there at all, even when I’ve tried to provoke it, however, the whistling at that RPM range has been in 1st, 2nd and 3rd until the car gets warm. Then it goes away. Changing the oil and trans fluid Saturday. I’ll update next week.

[Moeman10]

Update with solution!

99% sure that the “whine” I’m experiencing is from the aftermarket head unit. Radio off = no whine down a bumpy road. Same road, radio on, whine shows up after the first couple bumps, and stays there until the unit is turned off.

The “whistling” mentioned in my last post is a squeaky throw out bearing.