It's been a while since I was at the forum... guess I've been enjoying relatively trouble free car ownership
But now I'm starting to worry to the point of not wanting to take the car on longer journeys. Below follows a loong description. I’m really at a loss as to what this can be! Car info: 1998 tdi AFN with DHF 5-speed box, 268k km
Last summer I was getting increased front end noise combined with deteriorating handling. So I took the plunge and ordered a complete multilink suspension kit. As the noise was predominantly coming from the RH side I started there, replacing all links as well as shock absorber, dust covers and that rubber plate thing above the shock. I also replaced the brake discs, pads and caliper sliders (ATE/Teves), as well as the not-yet-leaking CV joint boot (I'm fairly confident that the CV joints are fine). I can't say I found any definitively worn parts either... But I'm just a normal DIY'er, don't know for sure how to really test for slack in these links. It took me more or less a whole weekend to do that one side in the late autumn! I yet haven't found the time to do the other side so I've been driving around with one good and one bad side for a few months now (I replaced brakes on both sides!)
It immediately seemed like the front end noise disappeared and I was relatively pleased with my half-arsed efforts. Though the handling still leaves a little to be desired (to be expected with 1 new and 1 old shock I guess....) But after a short while a similar noise started appearing again. In the last week or so it's been getting increasingly worse to a stage where it's more or less constant. Some descriptions and obervations:
It's a clunking type of noise. It can take on a somewhat oscillating characteristic, typically when coasting(?) along at constant speed with low power outtake. This can be on a smooth highway without any bumps. But the same noise appears also when driving over bumps. When coming down a slight hill to brake at an intersection I can sometimes feel as if something is shifting just as this noise appears. I recall seeing in another forum post about front end suspension links someone describing the same sensation.
It appears that whenever the noise appears (at least when at constant speed on smooth road) I can make it disappear by applying only very slight brake pressure (so little that the car doesn’t even slow down). Since replacing the front brakes I have had a lot of brake squeel, mostly at slow speeds. I also sometimes get a slight bind after parking, seemingly from the RH front. But when it loosens there is no sign of any dragging and there’s absolutely no heat generation indicating a dragging brake. The car always rolls very nicely with no apparant resistance. I test this daily when driving to work. It will roll and roll and roll for the longest of distances!
Another observation, which may be just a characteristic of the B5 Passat and has been there as long as I've owned the car (2.5 years): When doing tight turns at a parking lot, particularly if there's gravel on the asphalt, I sometimes feel that the front wheels slip, i.e. the car wants to go straight. I find this a little strange and something I would perhaps rather associate with older rear wheel drive cars...? I'm not saying it's related, just keeping my mind open.
About a month ago I jacked up the RH front and shook the wheel to feel for any play. I couldn't find any but when rolling the lifted wheel back and forth an ugly metallic noise could be heard. This made me worry about the diff. or gearbox as it was quite loud and sharp.
Last night I jacked it up again and took the wheel off. I used a rubber mallet and hit all the suspension links but could not find any looseness or metallic noise. I took off the brake caliper and examined the parts... nothing strange could be seen and the new pads had bedded in nicely and evenly. Really, I couldn’t fault anything so I put the wheel back on. To my amusement the ugly metallic noise heard last time I jacked it up did not seem to be there. I tried 1st gear and reverse as well as neutral. No abnormal noises! I also had a good feel on the driveshaft not finding anything there either. There is a little tangential play in the inner joint but it is definitely not more than the play in the left hand inner joint. The noise definitely comes from the right!
I also shook the engine to see if I could generate any noise from the engne mounts but no. I also put a jack under the gearbox to inspect the mounts.. couldn’t find anything abnormal. Having said that I’m not 100% certain how to check the engine and gearbox mounts!
I then did something one should never do! With the one wheel jacked up (and with a stand under of course) I started the engine and carefully engaged first gear. The car remained on the stand with the left wheel on the ground and the right one freely spinning. I then got out my stetoscope with the long metal rod and listened at the gearbox housing, making sure not to get my feet caught under the spinning wheel. I think there was a slight, rythmic clanking noise but perhaps not more than could be expected? Standing 1m away from the car I could juuust detect this noise over the diesel engine noise.
Eventually I put it all back together and the noise was still present this morning.
My own thoughts:
1. The oscillating nature and the fact that it goes away when applying brake pressure suggests that the noise is not really suspension related. After all I have also replaced all parts that could create noise right?
2. It looks to me like the driveshaft itself is fine. I haven’t looked at the inner joint other than seeing that the boot is intact. The outer joint I personally inspected, regreased and gave a new boot only few months ago.
3. That leaves me with three suspects, ranged in order of suspiciousness:
a. Gearbox /diff has something going on. I also noticed that the reversing lights are gone and it’s not the bulbs or the fuse. But I think the noise started before the lights went so probably not related... Strange how a month ago there was this ugly metallic noise and last night nothing abnormal. Is there a loose part inside the gearbox?? But why does the noise go away when applying brake? Because it stops the oscillations? There is very little on the gearbox in Haynes.. Diff endlash feels big but I don't know what it should be.
b. Engine / gearbox mounts? Could explain the “shifting†sensation sometimes felt when braking. But why does the noise go away when braking??
c. Wheel bearings? But these are supposed to last forever, right?? *There is no obvious noise when spinning the wheel but then I find with disc brakes that there’s always so much friction noise from the brakes that it’s hard to hear much else.. I can’t say I feel any play when wiggling the wheel either. However, I think that this is the only culprit that could explain the occasional binding brake, of course apart from the brake itself. Maybe even the squeal if it allows the disc to come to an angle with the pads?
d. Brake caliper? They are approaching 300k kms and have probably never been rebuilt (apart from the new sliders fitted by me). I did however use a file to ensure that all parts could move freely not hindered by old rust and dirt.
e. ABS components? Could the wheel sensor be making trouble? As far as I know they don’t actually touch the teeth on the CV assembly, or..? Could a troubled ABS pump unit be causing this? I guess not.. There is no warning light coming on. It did last year but that was because the cable to the left front sensor had been touching the wheel and worn through. Once fixed the light disappeared again.
So, what does the jury think? ANY suggestions would be greatly appreciated!
Thanks in advance!
Kristian