A Terrible Crackin' Sound

[Johan[TDI]]

Hello Guys,


I have a problem with my passat. It goes like this.
My car makes a terrible cracking sound when I brake hard or when I drive the car backwards. So, when I brake hard, the nose of the car heads down and the rear lifts up. That is obvious of coarse.
It makes the same noice when I drive backwards. Again, not when I m parking or so but when I drive backwards just a little harder/faster than usual. For example; When you are in a hurry The sound is always the same.
In the beginning I thought it were the rear shock absorbers (stoßdampfers). I replaced all 4 shock absorbers. But as you can geuss that wasn't the problem. :wall:

When you are in the car, the noice seems to come from underneath the driver and passenger's seat. The seats are perfectly fine, and when you hear the sound you become scared, cause it gives you the impression that the car is going to break in half :help:

But for the rest my car drives superb (it has 150Tkm). It Brakes very well, nothing wrong with the gearbox so far, steering is good so ... :? :?:

My passi has to the service station no matter what, but before I'm into that I would like to ask it on this forum.

Have some of you had same problem and what was it then ?

Thanks for reading my message, I hope someone can give some advice in this.

Johan[TDI]

 

[schemi]

Hi Johan!

Sounds it eaven so when you drive
in a corner???

1st Idea:
Have you checked the "Querlenker" ???
Try this: above and behind the front
tires are bars with joints.
Try to move them a bit ...
Of course they must not been able to move!
The bad sound may come from the joints.
(oh god, my english is terrible)

2nd idea:
Perhaps it may be one of the "Antriebswellen"
(the bars wich brings the power from the
motor to the tires)

 

[Johan[TDI]]

Hi Johan!

Sounds it eaven so when you drive
in a corner???

1st Idea:
Have you checked the "Querlenker" ???
Try this: above and behind the front
tires are bars with joints.
Try to move them a bit ...
Of course they must not been able to move!
The bad sound may come from the joints.
(oh god, my english is terrible)

2nd idea:
Perhaps it may be one of the "Antriebswellen"
(the bars wich brings the power from the
motor to the tires)

Hi Schemi,

First of all, thanks for the reply :top:

@ Your First Idea:

The cornering is perfect, really, especially with the new stoßdampfers. I don't feel anything unusual in my steering wheel or in my pedals.
I'm going to check those things you have told me for sure 8) That will be next weekend. I 'm going to check the entire suspension anyway, the bearings, the springs ... .

@ Your second Idea:

That is possible. Indeed, I totaly agree with you, I think it has something to do with the suspension. It is nice to read this, cause I share the same opinion.

In a way I wish that I could tell you a bit more. But it could be anything. I will keep you (guys) in touch when I know more about it.

When you come up with something else, please feel free to tell me I 'm always interested :!:

And schemi, your English is good mate :gut:
I really appreciate that you respond in a foreign language, and no problem about those German words you have used, I buy the Sport Auto magazine every month.

Grußen aus Belgien, looking forward to hear and tell more about this.

Johan[TDI]

 

[Geri]

Hi Johan,

I also think this could be the drivepulleys (Antriebsachsen). But indeed it`s difficult to diagnostic a sound without hearing it.

Maybe you should try this: Engine off, put in first gear and a friend helps you to push the car back and forward. While this you try from outside to locate were the sound is comming from.

Good luck! :top:

 

[Manfred]

I once had some real scary sound coming from right underneath the car, too.
Since we've both got a turbodiesel engine and therefore some of the major parts should be the same I think it could be worth telling what it was with me.
(Though the thing you've described sounds somewhat more serious.)

The TDI engine has got some big plastic shields (two of them) that both protect it against mud and dirt from underneath and also cover it to the outside as to make it run less noisy.

At my car, these plastic shields got loose and slack for whatever reason and produced a sound just like the one you describe. Whenever a sudden change in direction or a sudden push occured - and that's definitely the case when going backwards rapidly or braking, since braking it just a negative push - the shields moved a little. Actually, that's nothing serious at all, but the loud cracking sound it produced got me more than worried.

Once I had those shields fixed - the first one covers the front, the second one the rear of the engine lower parts, both the shields are joined by one of more screws where they touch in the middle (there they leave a slot through which you can see the metal of the engine) - the sound was gone.

Hopefully, I've been able to just give you one more point to consider.
As I said, I somehow have a feeling, that your issue is sort of more difficult to deal with.

Happy hunting!
M.

 

[Johan[TDI]]

Hi Johan,

I also think this could be the drivepulleys (Antriebsachsen). But indeed it`s difficult to diagnostic a sound without hearing it.

Maybe you should try this: Engine off, put in first gear and a friend helps you to push the car back and forward. While this you try from outside to locate were the sound is comming from.

Good luck! :top:

@ Manfred

Yes, you are completely right. My car has those as well. I have seen those plastic covers before, when I changing the motor oil for example. As you guys probably know yourself, you have to loosen one of those so you can drain the oil out of the engine. That is a good point, cause my car is lowered and if you know how horrible the roads are here in Belgium ... Not mentioning those safety islands, hate them !!!
Although, I would be surprised in a way that those plastic covers can be responsible for such a cracking noise.

But those plastic covers will not be forgotten next weekend during the check-up

Thanks for your reply :top:


Grußen aus Belgien

Johan[TDI]

 

[Johan[TDI]]

Hi Johan,

I also think this could be the drivepulleys (Antriebsachsen). But indeed it`s difficult to diagnostic a sound without hearing it.

Maybe you should try this: Engine off, put in first gear and a friend helps you to push the car back and forward. While this you try from outside to locate were the sound is comming from.

Good luck! :top:

Hi Geri,

Once again thanks for the tip. I will try this as well

I want to add the following thing. The noise that I hear when I brake hard or when I 'm driving the car backwards also appears when I drive over a bump and especially by lower speeds. In a residential area where you have a speedlimit of 30 or 50 kmh, when I drive over a rough bump and I listen carefully I can hear that same cracking sound from time to time. But I have to be focussed then. The noise is audibly for just a split of a second. It is clearly that it is the same noise, no doubt. But during hard braking or driving backwards you hear the noise constantly. So, from the moment I hit the brakes and the nose of the car heads down the sound occurs until the car has stopped. Same thing when driving backwards.
What I can add as well is that in those situations I don't feel any vibrations in nor my steering wheel nor the pedals. Does this don't shut out that there is something wrong with the drivepulleys (Antriebsachsen)? I ask you guys this because the steering wheel and the brake pedal are connected to the suspension.
Please tell me if I 'm wrong :!: Can you explain what sort of wear there can be?

Thanks for the replies, it is great reading those :zustimm:


Grüßen aus Belgien, will keep in touch

Johan[TDI]

 

[Johan[TDI]]

Underneath the passat exhaust system you have an alloy strip.
This strip was forced :!:
It was bended, and due the forces which occurs when I was braking or driving backwards a screw that helds two parts of the exhaust system together came against this alloy strip and made that awful noise

Luckily it was just that 8)


I will post a photo of that strip later on the day

Thanks for the tips :top:


mfg

Johan[TDI]

 

[Johan[TDI]]

I will post a photo of that strip later on the day




Voila Here is the picture I had promised you earlier on.

http://users.pandora.be/jokke1/pic1.jpg

MFG


Johan[TDI]