M47 Diesel Engine Whine / Whistle On The Overun - Page 6

HarryM1BYT · 15th August 2010, 09:38

I now seem to have tracked my noise down....

Just to remind - it only does it when I am decelerating + when I blip the throttle at tick-over and the engine speed is falling back to tick-over speed, times during which no fuel is being used at all.

It is difficult to reproduce when the car is stationary and it needs someone to blip the accelerator just right to get it to create the noise, but my noise is from the electric pump under the bonnet. Not the pipework, not the pump casing rattling, but generated internally to the pump.

Jules · 15th August 2010, 21:46

Thanks Harry
But the noise is there for a lot of Facelift owners (and some late Mk1's) who don't have the secondary pump!

Maybe your pump is just acting as a "soundbox" to the source of the noise resonating back through the fuel lines.

Interestingly I notice yours is a 131.
It's the 131's this resonance largely affects.

HarryM1BYT · 15th August 2010, 22:11

Hi Jules,

I suppose I could try unplugging the pump when it is making the noise - trouble is it would need very quick reactions. As well as feeling for vibrations on the pump body, I also checked the in and out pipes. Damping them with my hand made no difference to the volume of the noise.

Jules · 15th August 2010, 22:24

The noise immediately disappears when you disconnect the HP fuel regulator plug. (try it on yours Harry)
The electrical pumps are still running then, so that's why I concluded the noise is in the HIGH pressure lines and HP related.

pablo892 · 21st September 2010, 11:01

Hi Guys,

I think I have this noise too, but need to make sure it's the same thing.
Mine is most noticeable when changing gear, especially first & second.
As soon as I lift off and drop the clutch, I get a loud whine/moan for about 2/3 seconds.
It makes it sound like it's the clutch going "oooooh".

I notice it on the over-run too, mostly third and second gear. If I lift off, to turn into my work entrance etc, I can hear the noise in the background but not as loud as when changing gear.

Does this sound like the same thing?

Thanks,
P

Jules · 21st September 2010, 11:09

A quick DIY test is to turn the ignition off while still in gear driving along
(obviously where it's safe to do so)
This removes the power from the ECU & hence the fuel regulator.
If the whine stops immediately, (but engine still rotating without power) you know its fuel resonance.

Frank Incensed · 21st September 2010, 21:04

Quote:

Originally Posted by Jules

A quick DIY test is to turn the ignition off while still in gear driving along
(obviously where it's safe to do so)
This removes the power from the ECU & hence the fuel regulator.
If the whine stops immediately, (but engine still rotating without power) you know its fuel resonance.

I'm not going to try this as i don't think either me or the car would like it. However, I'm certain I've got the described noise, although (to me) it's faint and it doesn't bug me too much. It's among the symphony of strange noises the car makes. I've now done about 3K miles in the 3 months I've had the car, and at least half the noises have appeared in the last 1000 miles. This has also coincided with the drop in air temperature. However, this particular noise seems to have arrived immediately after I cleaned the EGR. Would that have any bearing on the resonance?
You'll have a field day at the North Wales meet on Sunday Jules. I think I might need your undivided attention! What sort of biscuits do you like?

HarryM1BYT · 21st September 2010, 21:45

[QUOTE=Frank Incensed;591088 I've now done about 3K miles in the 3 months I've had the car, and at least half the noises have appeared in the last 1000 miles. This has also coincided with the drop in air temperature. However, this particular noise seems to have arrived immediately after I cleaned the EGR. Would that have any bearing on the resonance? [/QUOTE]

Probably like me, you started to hear the noises more as you became more used to the car. Your concentration was able to move from the driving, over to its noises.

I had the noise before I cleaned the EGR, I had it afterwords and I still had it when I fitted the EGR bypass - no change at all. You can probably track down the apparent source of the noise by getting someone to blip the throttle whilst the bonnet is up - my noise appears on the overrun, as the engine slows back down to a steady tick over.

Frank Incensed · 21st September 2010, 23:52

Quote:

Originally Posted by HarryM1BYT

Probably like me, you started to hear the noises more as you became more used to the car.
I had the noise before I cleaned the EGR, I had it afterwords

Thanks Harry.

It's been suggested that the noise is from resonance in a high pressure fuel pipe. If that were so couldn't the problem be easily fixed by changing the length of the pipe?

flyer_phil · 22nd September 2010, 12:41

It must be something that was changed on the late Mk1's and Mk2's. My friend has a 52 plate club tourer and his is fine.

Mine is a 53 plate late MK1 and I'm blowed if I can find it. With the car stationary and increasing the RPM, it starts moaning at about 1800 rpm. I've had my head under the bonnet with an assistant operating the throttle but it obscure were it emanates from.

However when driving along I get the opposite effect. With the throttle open there is no noise, but as soon as I close the throttle then I get it.

Lets hope Professor Jules can come up with a solution. It really is very annoying.

15th August 2010, 21:46	#52
Jules This is my second home ZT 260 SE Twilight and 10 other 75 ZT's :O Join Date: Jan 2007 Location: Conwy NORTH WALES Posts: 11,094 Thanks: 512 Thanked 1,116 Times in 763 Posts	Thanks Harry But the noise is there for a lot of Facelift owners (and some late Mk1's) who don't have the secondary pump! Maybe your pump is just acting as a "soundbox" to the source of the noise resonating back through the fuel lines. Interestingly I notice yours is a 131. It's the 131's this resonance largely affects. __________________ [SIGPIC][/SIGPIC] Newbies do now!! 1. Plenum drains..all 3 or 4 year dependent 2. Cooling fan..All speeds functioning 3. Bonnet cable divider block

15th August 2010, 22:24	#54
Jules This is my second home ZT 260 SE Twilight and 10 other 75 ZT's :O Join Date: Jan 2007 Location: Conwy NORTH WALES Posts: 11,094 Thanks: 512 Thanked 1,116 Times in 763 Posts	The noise immediately disappears when you disconnect the HP fuel regulator plug. (try it on yours Harry) The electrical pumps are still running then, so that's why I concluded the noise is in the HIGH pressure lines and HP related. __________________ [SIGPIC][/SIGPIC] Newbies do now!! 1. Plenum drains..all 3 or 4 year dependent 2. Cooling fan..All speeds functioning 3. Bonnet cable divider block

21st September 2010, 11:09	#56
Jules This is my second home ZT 260 SE Twilight and 10 other 75 ZT's :O Join Date: Jan 2007 Location: Conwy NORTH WALES Posts: 11,094 Thanks: 512 Thanked 1,116 Times in 763 Posts	A quick DIY test is to turn the ignition off while still in gear driving along (obviously where it's safe to do so) This removes the power from the ECU & hence the fuel regulator. If the whine stops immediately, (but engine still rotating without power) you know its fuel resonance. __________________ [SIGPIC][/SIGPIC] Newbies do now!! 1. Plenum drains..all 3 or 4 year dependent 2. Cooling fan..All speeds functioning 3. Bonnet cable divider block

15th August 2010, 09:38	#51
HarryM1BYT This is my second home 75 Contemporary SE Mk II 2004 Man. Sal. CDTi 135ps, FBH on red diesel, WinCE6 DD Join Date: May 2010 Location: Leeds Posts: 17,273 Thanks: 2,160 Thanked 2,061 Times in 1,586 Posts	I now seem to have tracked my noise down.... Just to remind - it only does it when I am decelerating + when I blip the throttle at tick-over and the engine speed is falling back to tick-over speed, times during which no fuel is being used at all. It is difficult to reproduce when the car is stationary and it needs someone to blip the accelerator just right to get it to create the noise, but my noise is from the electric pump under the bonnet. Not the pipework, not the pump casing rattling, but generated internally to the pump.

15th August 2010, 22:11	#53
HarryM1BYT This is my second home 75 Contemporary SE Mk II 2004 Man. Sal. CDTi 135ps, FBH on red diesel, WinCE6 DD Join Date: May 2010 Location: Leeds Posts: 17,273 Thanks: 2,160 Thanked 2,061 Times in 1,586 Posts	Hi Jules, I suppose I could try unplugging the pump when it is making the noise - trouble is it would need very quick reactions. As well as feeling for vibrations on the pump body, I also checked the in and out pipes. Damping them with my hand made no difference to the volume of the noise.

21st September 2010, 11:01	#55
pablo892 Newbie MG ZT 135+ Join Date: Sep 2010 Location: Preston Posts: 27 Thanks: 0 Thanked 0 Times in 0 Posts	Hi Guys, I think I have this noise too, but need to make sure it's the same thing. Mine is most noticeable when changing gear, especially first & second. As soon as I lift off and drop the clutch, I get a loud whine/moan for about 2/3 seconds. It makes it sound like it's the clutch going "oooooh". I notice it on the over-run too, mostly third and second gear. If I lift off, to turn into my work entrance etc, I can hear the noise in the background but not as loud as when changing gear. Does this sound like the same thing? Thanks, P

21st September 2010, 21:45	#58
HarryM1BYT This is my second home 75 Contemporary SE Mk II 2004 Man. Sal. CDTi 135ps, FBH on red diesel, WinCE6 DD Join Date: May 2010 Location: Leeds Posts: 17,273 Thanks: 2,160 Thanked 2,061 Times in 1,586 Posts	[QUOTE=Frank Incensed;591088 I've now done about 3K miles in the 3 months I've had the car, and at least half the noises have appeared in the last 1000 miles. This has also coincided with the drop in air temperature. However, this particular noise seems to have arrived immediately after I cleaned the EGR. Would that have any bearing on the resonance? [/QUOTE] Probably like me, you started to hear the noises more as you became more used to the car. Your concentration was able to move from the driving, over to its noises. I had the noise before I cleaned the EGR, I had it afterwords and I still had it when I fitted the EGR bypass - no change at all. You can probably track down the apparent source of the noise by getting someone to blip the throttle whilst the bonnet is up - my noise appears on the overrun, as the engine slows back down to a steady tick over.

22nd September 2010, 12:41	#60
flyer_phil Loves to post Rover 75 CDT Classic, 2003, Moonstone Join Date: Mar 2008 Location: Chesterfield at the moment Posts: 411 Thanks: 0 Thanked 1 Time in 1 Post	It must be something that was changed on the late Mk1's and Mk2's. My friend has a 52 plate club tourer and his is fine. Mine is a 53 plate late MK1 and I'm blowed if I can find it. With the car stationary and increasing the RPM, it starts moaning at about 1800 rpm. I've had my head under the bonnet with an assistant operating the throttle but it obscure were it emanates from. However when driving along I get the opposite effect. With the throttle open there is no noise, but as soon as I close the throttle then I get it. Lets hope Professor Jules can come up with a solution. It really is very annoying.