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I have just purchased a 97 P 5 door 1.4 CL with 53K on the clock. When I decelerate there is a single knocking sound coming from what sounds like the bottom of the engine compartment but it is hard to tell. At speed (60mph) when decelerating quickly (but not just when braking) the knocking sound is repeated maybe 3 or 4 times. There is no feedback in the steering wheel. There is no knocking sound when driving in a circle at low speed with full lock on and no sign of CV boot damage. The car has been held on the handbrake to try and rock the engine forward and back to see if there is play in the engine mounts and they all seem solid (the underside rear mount included). The exhaust does not appear to be knocking anywhere on the car at all and trying to shake it to reproduce the knock has not achieved anything.
Basically what I am trying to say is that I am completely stumped! As a new member of this forum I would be very grateful for any advice or ideas that I could try to diagnose the problem before I take the car to a dealer and spend an extortionate amount of money for what could be a simple problem (I hope!).
Question - If when you decelerate and hear the knock, have you tried to immediately accelerate? Does this produce a similar knock? I'm thinking drive shaft. Raising the front of the car and examining the free play on the front wheels may eliminate this as a possibility.
I presume the knock only sounds when you are in gear. Have you tried dipping the clutch just as you take your foot off the accelerator? If you still get the noise I'd think that there's something loose under the engine bay.
Can't think of anything else
Good luck
Thanks for the advice having tried everything you suggested I can report the following results.
The knock only occurs when decelerating not when accelerating. I have jacked up the front of the car and found that the wheels do not seem to have any play in them (if I am doing this right I turned the driveshafts by hand forward and backwards and did not feel any delay in the action of turning the wheels ie no sloppiness).
The knock is present when the clutch is depressed and deceleration occurs. The other thing that I noticed is that the same knock is apparent going over small bumps like on and off a flattened curb.
Does this reinforce what you were saying about something loose in the engine bay? I have pushed and pulled everything with all my might but to no avail. What would you do as a next step? Is it time to bite the bullet and get the car down to a garage?
A knock going over small bumps (from the front of the car) is likely to be one of two/three things.
(i) the bushes on the lower are assembly are warn/split. If this is the case a complete assembly replacement is usually the best and most cost efficient option
(ii) The lower ball joint is warn to excess. - simple swap.
(iii) The anti-roll bar may have come adrift from its mounting - (dealer part - I think)
Repair is likely to be about £100 top.
A VW dealer will charge signifiacently more as they will fit genuine parts etc.
Gazza, thinkI might have found the culprit. It looks like the lower arm rear mount has given way. The mount has slid off the rubber and is touching the subframe. I have a photo that I would like to email you for confirmation is there any way you could PM me with you address so that I can send it to you. Incidentally and rather disturbingly there is a complete lack of Antiroll Bar. It just isn't there! I have the Haynes Manual and it shows there should be one. Can you confirm that there should be one on this car and Finally can you recommend where I could source the parts from (more particularly what exactly I need to replace. Thanks again for all of your help. David
It appears that the rubber has separated from the outer metal ring that sits inside the lower arm. I have just purchased one for £9 at my local dealer. Is it a difficult job to press the new one into place or will I need to get a garage to to this with a press of some sort?
Not too expensive for the full part. This is the full metal assembly from the body mount to the lower ball-joint (including the rubber bushes)- The bush itself is also avalable I would imagine.
I am not an expert by any means and have very limited experience of VWs.
You have two alternatives - remove the entire assembly and decide whether the rubber bush can be replaced or whether its better to replace the entire assembly.
Either way you would need to get the thing off. These parts are widely available - best to take it with you when you collect/order the part. Any good local MOTOR FACTOR will be able to get one for you in a matter of hours
I can't give any guidance as to whether an anti-roll bar is fitted to ALL models.
Thanks again. I will remove the lower arm and take it to my local garage to ensure that the bush is inserted correctly. Hopefully this will fix the knock. I have managed to source an anti roll bar and all of the fittings for £25 at a specialist VW breakers. I will keep you posted as to how it goes. David
Update: Slowly but surely I am learning. I have just discovered through reading Haynes that only the 1.6 and Diesel models have Anti Roll Bars, although the local VW dealer was quite prepared to sell me one when I enquired about the price!
Just to finish this one off. I have just replace the rear lower arm bush where it mounts into the subframe £9 for the bush at a VW dealer (incidentally Eurocarparts was going to charge£16). I took the lower arm to a local garage to have the new bush pressed into the lowerarm for £5. Problem fixed!!!! No more knocking sounds and thanks to this forum and Gazza in particular the whole affair only cost me £14!. Thanks again, David
