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Rear Suspension Knock


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Hi All,

having changed my 18" wheels over to 17" wheels in order to overcome the dreaded teeth rattling ride when travelling over badly surfaced roads here in the Cullompton area of Devon, I now have another problem that has reared it's ugly head. For some reason I am now getting a "knocking" noise comming from the nearside rear suspension when going over badly surfaced roads. I have tried to do many tests in order to try to find out where it is comming from. Each test that I have made have been with the rear seats laid flat in order to make sure that I can hear the noise better....

First Test.....I emptied the boot of all items .....no joy.

Second Test.....I hooked the boot floor tray up with the "clip" and left it hooked up, result...no joy.......

Third Test......removed the Space Saver and Tool Tray and left the Boot Floor hooked up, result....still no joy....

.Fourt Test......Took car to Grange at Exeter. They could not find anything wrong. To be fair they arranged for one of their Mechanics to travel with me in the car in order to try to locate the problem. Unfortunately we did not have enough time to locate a badly surfaced road in the vicinity of "Grange"

So I am now experimenting with the tyre pressures in increments of 0.5lbs/sq". This knock did not used used to be there. I know that the tyre tread depth is going down but it is still aroud 4mm. My Brother mentioned to me that the suspension units on cars used to be held onto the top of the body by 3 bolts, but on some modern cars they are only held on by just one nut this being the one on the top of the damper. Does anyone know what holds the Spring/Damper unit onto the body of the XF. I am looking at this in case the problem might be in this area. I assume that in order to see theTop of the Rear XF suspension unit then the covering in the Boot would have to be removed........Any thoughts in this problem really would be appreciated as the noise is driving me mad........my XF has only done 11, 800 miles

Regards to All.........Billboy

3.0D XF Premium Luxury in Sattelite Grey

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hi bill sorry to hear of your problem and only to glad you have an xf.  I am new to forums. but in spare time log on. have checked out other forums much busier than this one but not as friendly (I found)  but this forum seems full of the older models & owners.  I feel that I have to recruit newer model owners to bring newer blood into it as it will die in a couple of years without them, you can only flog an old horse for so long lol but hope you get to the bottom of your problem joe

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Hi William,


I am not an engineer, but I think that you have done all the things I would do to find the knock.  I would be inclined to take off he wheels and examine them carefully prior to anything else.  I had a knock at certain speeds some years ago, and found some damage to a tyre on the inside.


And while the wheels are off, take a good look at the suspension and shock absorbers.  Bad roads and potholes do take a toll on those bits!!





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Hi Peter and Joe,

many thanks for your reply. I have had the wheel off twice and double checked all of the suspension bushes etc. However today I managed to meet a good friend of mine who has a good knowledge of mechanics. We therefore were able to carry out a test whilst the car was in motion. I lowered the rear double seat and I drove the car with my friend almost lying inside the boot. He said the knocking noise was NOT comming from the suspension but it appeared to be comming from beneath the boot floor at the rear of the car. Having made previous tests with the spare wheel removed, and the knocking still audable I knew that it was not a loose spare wheel. HOWEVER there are only two items that are left. One of these is a large box which I think is to do with the Audio system, the other is the Fuel Tank. I don't know if you have heard of "Fuel Slap" on the XF. This is the noise of fuel being thrown around and hitting the sides of the tank when you go over slight "bumps". Jaguar cured this by inserting something into the tank its-self in order to stop the noise. I had this "Mod" carried out by my Jaguar Dealer free of charge. I have today tried to find out just what is was that was inserted into my fuel tank....Could this possibly be the culprit. I tried to find out from my Dealer but I cannot get any reply. However I did manage to contact someone who suggested that what had been inserted into my fuel tank may have become loose ?.....Does any Member out there know what is inserted into theXF tank in order to stop "Fuel Slap" ............Regards.......Billyboy

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Hi Billyboy,


I used to go into a factory when I was still working that made the steel used in petrol tank manufacture.  I once saw a petrol tank that had a flaw and was returned.


It had two baffles in it that stopped the fuel sloshing around.  ---  Metal fuel tanks I believe are no longer used by Jaguar, but I think that the principle must remain the same.


Hope this helps.


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have just read an artical by "dervnut" (dated 01-10-12). It is the info for a Jaguar Technician to install a "Foam Baffle" inside the fuel tank of an XF. The Baffle is inserted into the tank via the Fuel Pump Assembly which appears to be located on top of the fuel tank beneath the rear seat floor covering. The artical gives instructions of how to gain access to the Fuel Pump Assembly and how to install the Foam Baffle. So this is what Jaguar does in order to quieten the Fuel Slap problem. It also answers my question of what is inserted into the XF Fuel Tank. Also I contacted Jaguar about my "Knocking Noise" in the rear section of my XF. They told me to book an appointment with a Jaguar Dealer which I have done. But this time I am going to a Dealer in Taunton. They have booked me in with a 1 hour slot so that a Mechanic can travel with me in my XF in order to try to locate the problem. Maybe it is the Foam Baffle that has come adrift in the tank. I sure hope that I get the problem sorted out as I love the XF. Also I have heard a whisper that Diesel is not fashionable anymore in the 3.0 litre guise from 2016. I notice that the New Jaguar Engines do not include a 3.0 litre Diesel but only a 3.0 litre Petrol Engine. Has any Member heard anything on this subject........... Many Thanks for your replies...........Billyboy

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Hi Billyboy,


Taunton Jaguar have a better reputation that Grange in Exeter, or so I hear.


On the question of engines, the new Jaguar engine plant in Wolverhampton  is currently manufacturing engines for the new XE model, and they are 2.0 litre diesel engines, and a 3.0 litre petrol engine for the R version.  I think that all these engines are 4 cylinder and concentrate on fuel economy, and will obviously comply with the Euro emissions requirement.


The specifications for the XJ still appears include the 3.0 litre diesel.


The new  model, the F Pace --  modelling on the CX17 concept car will include diesel engines.


As yet, I have heard nothing about the use of the 3.0 Gemini diesel [Ford Peugeot design] in the new models, but I think I can safely assume that the new engine facility, which is concentrating on the 2.0 litre diesels at the moment might well design a larger diesel for the new XF and XJ models which will eventually be announced.





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Hi Billyboy,


I have just read that Ford and Peugeot are developing the Gemini engine to meet the Euro 6 requirements.


In an addition to my previous post, Jaguar's new diesels in the XE are quicker than the 2.7D and the 3.0D due to the use of aluminium now used by Jaguar, giving a better power to weight ratio.


So whether Jaguar will use the new Ford/Peugeot engine or manufacture their own larger diesel is yet unknown.


Having been retired for almost 16 years, my contacts in the Automotive industry and the SMMT are also spending more time on their Yachts or in their gardens!





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  • 4 weeks later...

Hi All,

a very, very happy XF owner here. I was plaqued with a mysterious knocking noise comming from the rear of my XF (see my topic on the 15th March 2015). I took my XF back to my Dealer (Grange of Exeter) who reported that they could not find anything wrong. In desperation I contacted the Jaguar Dealer at Taunton. They asked me to bring my XF to them in order to investigate the problem. As soon as I arrived a Technician listened to my story about the "knocking noise" when going over badly surfaced roads. The Technician immediately drove my XF along a country road that was really badly surfaced. He immediately heard the noise and said that there was indeed a problem. My XF was duly "booked in for 2 days" for investigation, and "Hey Presto" the problem was eventually located.....it was a Defective Nearside Damper Unit. This unit was changed under the Waurentee. My XF is now 100% and I am now a very "Happy Bunny". Of course it now goes without saying that I shall reward the Taunton Jaguar Dealership with my future requirements.

Regards to All...........Billyboy

3.0D XF Premium Luxury in Satellite Grey

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Hi Billyboy,


There have been several members who have had problems with Grange of Exeter.  I have used Taunton Jaguar for odd bits fro their online site and found them very obliging.


Glad all is well with your car now.





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