The Noise Machine

[BuyanythingbutaVW]

Hello all,

Just wondering if anybody help diagnose two noises that my 55 golf tdi (130) has started making in the engine bay area. Car has done 41,000 miles and the main fault that it has ever had is an air take inlet valve replacement at about 20,000 miles.

The first noise sounds like a hissing noise when driving and when the clutch is depressed, the noise lessens - usually happens when being driven hard and after about ten miles+. A quick search mentioned a noisy bearing for similar faults, but generally on much older or higher mileage cars.

The second noise is from the turbo, with the turbo always sounding like a police siren. The turbo has always made a similar noise, albeit quieter, but has recently got louder and has made passengers heads spin round looking for approaching police cars. The turbo is also what I would describe as lumpy when changing gears and trying to pick up.

The car is under warranty, but I wanted to ask the dealer to check the car and sound like I know what I am on about.

Thanks a lot for any help that you can give.

Jamie

[devonutopia]

Hmm, turbo could be being given dodgy signals due to a failing MAF sensor. The hissing noise has got me stumped, especially as it reduces when the clutch is in. Would you say it's just under power that it does it, and perhaps just lower down in the rev range? It could be the dual mass flywheel moaning if that's the case.

[chrisvrscrx]

My turbo whistled a bit like a siren and it was goosed. If I were you i'd get it back to the garage before your warranty runs out, otherwise it cound cost you ££££. Do you let the turbo run down before switching the engine off, and wait about 60 secs when the engine is cold before setting off. This stops the turbo failing earlier than it should.

[BuyanythingbutaVW]

In reply to a couple of queries that have arisen I would say that I just start and stop the car whenever I want. I didn't know that using your car when cold could damage a turbo.:confused:

Also when I press the clutch in my car doesn't lose power. However the hissing (or to be more precise a 'putt, putt, putt, putt' noise at high and fast frquency) just lessens. It sounds possibly like a loose hose or something like that, but when I switch off the engine and then restart it the noise has gone - bizzare.

As it is still under warranty I usually just wait for things to go bang or get a warning light, as the 'fitters' are no mechanics at my local VW garage. My local VW doesn't diagnose faults - just changes parts when they go bang.

Thanks for your ideas and thoughts - may ring the garage in the next couple of days.

Cheers

Jamie

[chrisvrscrx]

In reply to a couple of queries that have arisen I would say that I just start and stop the car whenever I want. I didn't know that using your car when cold could damage a turbo.:confused:


Alot of people don't know that, maybe the ******** don't tell you beause they coin it in when the turbo fails.

[Loofer]

I've also read somewhere that you should let the turbo spool down after a long drive. Let the oil in the bearings (of the turbo) drain back into sump.

I say I hav read this yet I don't act on it myself. 38 mile commute to work and I jut switch the engine off.

How long should one leave it at idle?

[Ben]

If its under warranty take it to the dealer and take one of their bods out for a spin.

I can't suggest enything else. There is no point. ITS UNDER WARRANTY - USE IT

[Ben]

. 38 mile commute to work and I jut switch the engine off.


Me too.:D

[chrisvrscrx]

I've also read somewhere that you should let the turbo spool down after a long drive. Let the oil in the bearings (of the turbo) drain back into sump.

I say I hav read this yet I don't act on it myself. 38 mile commute to work and I jut switch the engine off.

How long should one leave it at idle?

Between 30 and 60 seconds. Because the turbo is so hot if you just switch the engine off the oil that is on the bearings just dries out as the turbo still spins very fast, causing wear. By leaving the engine switched on for about 30-60 secs the oil can lubricate the bearings and the turbo can run down. Also not changing the oil regular enough can cause the bearings to fail too. Crappy oil prevents the correct lubrication. This happend to mine and the bearings failed/worn causing the whistle then the turbo detonated big time, at this point I had a little cry ;)

[Loofer]

Between 30 and 60 seconds. Because the turbo is so hot if you just switch the engine off the oil that is on the bearings just dries out as the turbo still spins very fast, causing wear. By leaving the engine switched on for about 30-60 secs the oil can lubricate the bearings and the turbo can run down. Also not changing the oil regular enough can cause the bearings to fail too. Crappy oil prevents the correct lubrication. This happend to mine and the bearings failed/worn causing the whistle then the turbo detonated big time, at this point I had a little cry ;)

cheers for that... I think that unless people get to hear the science behind something (or they experience the repercussions of not doing it) they will never heed. I'll just try and get into the habit of remembering to let it cool down for a min or so.

I'm guessing the same applies to when starting up the engine... allow the oil to warm up for say 60 seconds or so for better lubrication

though I have read somewhere that in diesel engines, starting the car and leaving at idle has very little effect on warming up the engine... better of to just drive (gently)

wotchu say bout thah?

[chrisvrscrx]

cheers for that... I think that unless people get to hear the science behind something (or they experience the repercussions of not doing it) they will never heed. I'll just try and get into the habit of remembering to let it cool down for a min or so.

I'm guessing the same applies to when starting up the engine... allow the oil to warm up for say 60 seconds or so for better lubrication

though I have read somewhere that in diesel engines, starting the car and leaving at idle has very little effect on warming up the engine... better of to just drive (gently)

wotchu say bout thah?

Yeah I agree about it not warming the engine. However, leaving it for 60 secs or so just gets the oil lubricating the turbo. Then I drive my car really gentlely until its up to temp, then I drive normal, or thrash it sometimes ;)

[BuyanythingbutaVW]

I've taken the car to the dealer and they are having it tomorrow to look at. It may be with them for a couple of days, but if it gets this problem sorted then mission accomplished.

The service manager did say that if it is the turbo, as he thinks and it decides to let go, then it may take the engine with it. He explained that parts of the turbo could go into the engine or the turbo (or was it the engine) will just try and burn the oil in the engine and then bang.

Anyway made it home and hopefully it only has to make it to the garage tomorrow before it gets fixed.

I stick by login name - 'buy anything but a VW'. I have a Smart Roadster and I thought that has issues, but this VW Golf takes the biscuit. Maybe I just got the Friday afternoon German Lemon. I think quality control had the day off when this car was put together.

Anybody want to buy a 55 plate 2.0 Golf GT TDI, 41000 miles and most of it renewed under warranty - It goes by the nickname 'a bag of nails' :D

[BuyanythingbutaVW]

Thanks to everyone who replied to my question and gave their advice. The VW dealer took possession of my car today and diagnosed a blown turbo :D.

The turbo is now going to be replaced and then the car will be test driven to make sure all the noises were turbo related. Hopefully get the car back tommorow.

Thanks again

Jamie

[arob]

cheers for that... I think that unless people get to hear the science behind something (or they experience the repercussions of not doing it) they will never heed. I'll just try and get into the habit of remembering to let it cool down for a min or so.

I'm guessing the same applies to when starting up the engine... allow the oil to warm up for say 60 seconds or so for better lubrication

though I have read somewhere that in diesel engines, starting the car and leaving at idle has very little effect on warming up the engine... better of to just drive (gently)

wotchu say bout thah?

Hi, There are two main reasons for leaving the engine running for a short period one of which is explained above, the other reason is that a turbo charger uses a oil bearing which essentialy is not a bearing at all, because of the high rpm of a turbo (from memory about 30,000 rpm) it is to expensive to manufacture a bearing to handle this, so what hey do is feed the spindle housing with pressurised oil that sits between the spindle and the bush, so the spindle actualy runs on oil with no touching parts. when you turn of the engine before the turbo has stopped spinning you lose oil pressure and the spindle touches the bush giving you metal to metal friction resulting in a worn turbo.
It only takes a few seconds to stop spinning so its worth the effort.