GolfGTIforum.co.uk
Model specific boards => Golf mk3 => Topic started by: JaminDub on 05 November 2007, 10:01
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Hi guys. Previously posted in the garage section about this, but just noticed the reduced mpg figures i've been getting. The rasping, metallic noise is only when I accelerate, but it's all the time. Even when I start up first thing in the morning, when it's freezing cold!! I've had it for about a week now and my mpg has gone from around 34/35 to 27/28, doing exactly the same routes and drives as before.
Had it checked at a garage and they blamed on the k&n filter making a sucking in noise, but I'm just not happy with that!! It sounds far to metallic for it to be air. Anyone else experience something similar? Been told pinking is an option, although it shouldn't really happen on a mk3?? It's a 1996 16v. Oh - recently took the air intake off, could it be anything to to with that? Gonna put the air intake back on, then if nothing changes, will put the old filter back on, but wanted to avoid the hassle of having to do that, as i do love the filter noise!! Any help/suggestions are welcome.
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Exhaust related?
I know the CAT shield come loose and/or the fixings rust away. This normally just makes a sound at certain revs? Any ideas where the noise is coming from?
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my whole car vibrated really bad when my exhaust shield fittings rusted away, ended up taking it off altogether :)
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That was the first thing the mechanic thought when I took him out for a spin in it, he said 'exhaust' straight away, and I must admit - it does sound exhaust related at first hearing. But, he got it up on the ramp, checked the exhaust over and said it was all fine. He would've/should've noticed the exhaust shield/cat shield right?! Is there any way i can check those myself without getting it up on a ramp?
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If you wait until the exhaust is completely cold, be careful they get bloody hot!!! You can lean under the car and give it a tap. You'll soon know if its lose. Otherwise when stationary rev the car gently and with the door open look underneath. If its the shield you will certainly hear it!!!
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Thanks for the advice Lewism3. Will give it a try at lunch and report back!!
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yeah those shields are a very easy spot, no other sound like them on a mk3!! :)
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Thanks for your input too Bunter, much appreciated :smiley: Am on my way down to the car park now to have a butchers...
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let us know how you get on :)
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Right... had a look at my car. It's def an exhaust problem. Checked under car for any obvious loose parts, etc. Nothing to be seen. Then started her up, had a good listen. Got out under the back of the car whilst it was still running and there is an obvious small rattle towards the end of the exhaust. Sounds like something is rattling around inside the exhaust!! there is no obvious signs of wear from the outside, but what do i do now?! Pi$$ed off with the garage for not spotting it tbh, but they didn't charge me so musn't grumble. Taking it back up there tomorrow for another look. Anyone had something like this before??
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Happens all the time, it will be the baffles inside the exhaust that can loose. Mainly in the centre section.
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So will they have to take the exhaust off and replace/reomve the baffles? What are baffles? Sorry for being such a golf amateur!!
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Oh - forgot to mention something completely separate. It also seemed to be running quite rough as it was ticking over, any potential issues you guys can think of first hand? Tganks for all your help in advance! :smiley:
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I think things are going from bad to worse... I'm sure i noticed some white smoke coming from my exhaust whilst it was idling roughly earlier! :cry:
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Get it on VAG COM would be the first thing to do mate. Options could be a vac leak where you've not blocked the airbox hose on after fitting induction cone, leaking manifold/downpipe or an ECU coolant temp sensor
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White smoke will be emitted when its cold especially in this weather, start to worry if the car's warm.
Baffles are the "wall" sections inside the exhaust and sometimes get loose, hence the noise. A sign that the inside is going rotten. You can cut the box open and weld the baffles in place but it isn't really worth it.
Incidently, if it is the center box, you can buy a straight through pipe instead of the standard box system. Think R98 RUF (Simon) posted something on this. Remus do a s/steel version.
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Pete - Would the air box hose be quite a large(ish) hose. There was one that I didn't know what to do with and it is just stuck to the side now!? I blocked the small exit from the engine with the plastic cap provided (where there was a small hose going into before). The instructions where quite shocking, so kinda free-styled a bit when fitting it. I pretty sure it's all correct tho, just not sure about the big hose as mentioned before.
Lewism3 - Thanks for the advice, i hope it is just the cold weather! Been noticing a drop in my mpg recently and getting worried it's something more serious.
Thanks alot for all your help so far guys!! :smiley:
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The small 4mm vac hose should of been taken off and blocked at the throttle body. The other larger tube going into the throttle body next to it goes to the carbon cannister. The even thicker hose that comes from the ISV (idle stabilisation valve) above where your dipstick is should go back to the induction cone. Hopefully the mass aiflow meter meter from your airbox should be plugged into the back of the induction cone too otherwise the ECU has no hope of measuring what air the engine is getting to compare it with lambda sensor readings and adjust fuelling