Whining noise from 7AFE without clear source?

[Ceasar]

Hello!

I have got a whining engine noise i really cant locate and i dont make much sense to me. it's quite high.

So it's a high pitch sound whining sound, sound mechanical like a faulty water pump/alternator bearing.
But i did remove the accessory belt and the whine was still there. So it rules out those components.

Used a house as a stetoscope and located that the wine comes from the head close to where the oilcap is.
So i thought it was injectors, unplugged one at the time without any luck. Open and checked the cam's they looked good and couldn't find any play or reason for a sound.
Inspected the timing belt and tensioner and they did look ok.

Rotated the engine by hand but when i do that the engine is quiet.

So it only sounds when the engine is running, and the whining sound is the last thing i hear when i shut the engine of (except fuel pump).
It have a constant whine which i dont really can say follows rpm. but when i turn the engine of it seems to follow the slowdown of the engine.

Also checked PVC valve and airleaks which could produce weird sound's without any luck.

So do anyone have any clue what the hell is going on because it's driving me a bit crazy haha.

//thank´s and cheers!

[jondee86]

Might be worthwhile running the fuel pump while the engine is OFF. Somewhere you should
have a diagnostic plug or box where you can bridge (short) two pins to cause the fuel pump
to run any time you turn the ignition ON. If the sound does not follow the engine rpm it is
not likely to be mechanical.

Cheers... jondee86

[Ceasar]

Hello Jondee!

I have runt the fuel pump seperatly and it dose not seem to be that either!

Yeah i think it dont follow, it's very high pitch so.
Bust just that when you turn it of it follow's the engine down make me suspicious that it might follow rpm.

[jondee86]

I was thinking about something that involves pressure, like the fuel pressure regulator or the lubrication
system. A small internal leak or loose part that could vibrate under high velocity flow could make a noise
that would fade as the engine slows down. A vacuum leak on the intake side ?

Cheers... jondee86

[Ceasar]

Hmm, not a bad idea at all since i kind of rules out everything mechanical rotating (i think).
Is there a way to check FPR for this?

Have checked for intake leaks, but since i have a very weird intake now i wont hurt to do it again.

Just such a weird noise aswell, dont sound like anything i have heard, but will check intake and go stetoscope again to se if i can isolate it a bit more.

thanks

[jondee86]

The FPR will be manifold vacuum referenced, so theoretically, if you have the engine idling
(high vacuum) and remove the vacuum hose (no vacuum) you should get a change in pitch
or some other effect. Screwdriver to ear or stethoscope might pick it up.

Likewise, for a vacuum leak, the pitch or intensity should change when the manifold pressure
changes. So if it gets louder, quieter or disappears under certain throttle/load conditions
that might be a clue ?

Is the sound like a whistle that has constant pitch and just gets louder or softer ? Or is it like
an oscillator that has constant amplitude but variable pitch (like alternator whine for example) ?

Cheers... jondee86
so

[Ceasar]

So it seems to follow the engine rev, at least some. Didn't change when i removed the vaccum but with a hose as stetoscope (couldn't make out anything with screwdriver) i think it's something fuel related might be FPR anyway?

I have a bosch 044 which making quite some noise, but it's putting out both some high pressure and flow. Would this maybe make some problems with original FPR?

Hmm the sound very high pitch, quite sharp sound. Oscillating a little bit with some variable pitch.
Sounds like a alternator bearing would.

Tried recording it but couldn't get it but couldn't the phone to take it up.

[jondee86]

If the Bosch pump has a flow rate significantly higher than the factory fuel pump, and you
are using the factory FPR, then the flow velocity through the FPR will have increased. The
regulating device will also be open further than with the stock pump. Factory regulators are
very simple devices, typically some variation of this...



If they are asked to run well outside their original flow/pressure design point, then they could
become unstable and vibrate/flutter/bounce to create noise. One way to check this possibility
would be to temporarily reduce the load on the FPR by creating a pressure drop in the incoming
fuel line. if you can partially close a rubber line by clamping it with something that does not cut
or otherwise damage the hose, velocity at the FPR will be reduced.

If the noise goes away you have found the probable cause.

Hahahah... wrote all that before I remembered that you already ran the pump with the engine off.
Still, there are other variables such as the pressure fluctuations in the fuel rail caused by injector
openings that could come into play.

Are you still using your distributor relocation setup ? Does it have a bearing ?

Cheers... jondee86

[Ceasar]

Haha yeah.. it's a bit overpower for my 110bhp! But i definitely think you are on to what the problem is, running it without the engine running wont provide the vaccum that it have when sounding or the injectors adding to the unstabeness.

So since i cant stand the sound of the bosch (very load) either way i orderd a lower flowing/pressure pump that sits on the bmw e30 externally (how it's good enogh).

Either way it will be a good way to eliminate if the sound is the fuelsystem i guess?

No, i found a solution to move it! so running the bottom of the distributor for the sensors where it should be located. Havn't checked the bearing, and sadly i have to remove my engine to do it since it's sitting cosy against the firewall haha But really dont think it's the dizzy.

One think i cam to think about though, made a comp test before and notice a bit lower compression in cylinder 3 ( i think leaking valve steam on the exhaust) would that be able to make this sound? it a bit wrong location but it contains flow of high pressure

[jondee86]

The valve stem is on the low (near atmospheric) pressure side of the valve, and will not affect the cylinder
pressure with the valve closed. I suppose it could leak a small amount of exhaust gas into the head and that
gas would become part of the blowby that vents via the PCV valve. When the engine is idling you could take
the oil filler cap off and see if the noise changes. Cover the open filler with a bit of rag as otherwise it will
throw oil out.

Cheers... jondee86

[Ceasar]

So changed the fuel pump, and the fuelrail spacer and the sound seem to have disapered

And i can hear my engine again.. damn bosch 044 haha

Thanks for the help!

[jondee86]

Good work Apart from noise, the other possible downside with an oversize pump is that
it can max out the FPR. Once the FPR beomes fully open it can no longer regulate the pressure
and simply acts as a fixed orifice. When this happens the pressure in the rail can rise above
design and over fueling results. So to be on the safe side (if you have an aftermarket ECU)
check your AFR's to make sure that they haven't changed now that you have installed the
new lower capacity pump.

Cheers... jondee86