Hi All, I've had my s type for over 4 years now. I chose the NA 4.2 litre over all the over engine variants. Jaguar worlds opinion at the time was it's refinement and effortlessly performance. My opinion is somewhat clouded with the issues I've experienced to date.

What's got me annoyed is a low level vibration that is experienced via the accelerator pedal at 1200 rpm. This vibration is also accompanied with a low level groan. It's been getting on my nerves ever since I've owned the car leaving me questioning the true refinement of such a car.

It taken a long time to identify the issue. I drive around a windy inlet/harbour and it's all the twisting and turning when I notice it the most. It also occurs in a straight line but was less obvious. As I accelerate and ease off around corners on the windy road the speed drops down to 1200rpm and this is when the harshness comes into play.

So what is the problem? Has any one else experienced this issue? I initially thought it could be the electric brake pads grabbing. But I dismissed this. Other possible causes

Engine mounts. There have been cases with the v8 where harshness has been experienced. One of the fixes was to replace the engine mounts with those found on the v6. Can't locate that thread at the moment. Maybe someone has more detail?

The other info I found was XK dreaded drone at 1250rpm . The fix was TB00088 - Bracket Mount C2P13477 & C2P13478 , HEX BOLT JJFP10606B , NUT ****** JFN 106041. The brackets mount to the transmission and clamp around the exhaust were the catalytic converters are. I assume this could be the solution to my problems. However there may be differences to the stype /XK configuration.

Anyone experienced this harshness via the accelerator pedal?
My XKR has none of the above symptoms. Any thoughts much appreciated.

 

I've not heard of it before (or the XK JTB but I don't have an XK).

Be a bit patient so those who have or know the 4.2NA get a chance to reply.

I think Mikey has one - try a PM if he doesn't chime in.

 

I'm here, but have had nothing remotely similar to what you describe. Mine's as smooth at 1200 RPM as any other speed. Have you tried manually putting it in different gears on the same piece of road?

You are right dismissing the rear brake pads as they also act as the main foot brake pads unlike the R variant. i would question also the noise/vibration being transmitted via the gas pedal as there are no mechanical connections to the engine, only electrical.

sorry.

 

Good idea to use the J-gate.

It can be used to force the revs to 1200 but in a different gear to whatever one it's now choosing.

Also, to the same speed but rather more revs.

 

Took the car for a test driving. Used the j gate for each gear at a time. Every gear produced the same harshness bang on 1200rpm in each and every gear. Trying to maintain 1200 on a downward hill with the foot on the accelerator pedal was difficult but with no engine load the harshness was absent. So it appears to be load related that the harshness appears.
In top gear the harshness disappears at 1400. I didn't pay to much attention in the lower gears but I believe the harshness was in a very narrower rev band. I'll retest again in a few days. Don't want to upset locals with a slow moving Jag
As I've lived with this for 4 years, 10k miles I'm happy to guage any feedback. Not in a hurry.

 

Sounds like you're looking for an engine/engine bay thing then.

Engine mount?

 

Interesting. I thought it was just me.
I've got exactly the same issue as you on my 4.2 S type. I'm putting it down to some form of resonance as it seems to do it at standstill in park and neutral as well. So far, I've changed gearbox oil, diff oil and front wheel bearings one of which was shot, and also greased up the propshaft centre bearing, but still that same buzzing/grating through the throttle pedal at 1200 rpm.

I'd certainly be interested to hear if you ever got to the bottom of the issue.

 

Hi Mikey, I'm not sure I have the vibration /groan in neutral with no load on the engine. My next step is to book an appointment with the chief jag mechanic in Wellington and go on a test drive with him and talk it through. I'm do believe it's engine mounts so I want the mechanics thoughts on the issue . I don't want to invest in engine mounts if it's not the issue. They're not overly cheap.

I'll respond after the test but I have another issue with a coolant leak I need to sort first . It's taken a while to identify the issue but I'm 95% sure it's the thermostat housing. I have spotted coolant on the engine block just underneath the outlet pipe. I guess that's another issue for another thread. To much plastic in these cars

Back to the main issue here. I'm sure I've read somewhere a few years ago that there was an issue with some customers complaining about the harshness with some of the V8 engines in the s-type. I gather the fix was installing the v6 engine mounts. I just can't relocate the article. It could be in one of the Jaguar World magazines that I read monthly. Maybe I need to go back through past issues to locate it but no one here is familiar with the issue. You're the first to quote similar issue. If you solve before me, please let me know what your fix was. Cheers

 

I posted that my 2008 4.2 Stype has this vibration, resonanse issue at city driving speeds, goes away on acceleration and doesn't happen at highway speeds. I feel it as a vibration through the accelerator pedal. I have done transmission fluid change, rear end overhaul, front hubs and no change in it. I have been starting to think about idler pulley or something on the serpentiine belt system.

 

Yes I thought it didn't happen on acceleration myself at first as I normally go through the 1200rpm rather quickly. It took a very long time to figure out it occurs in a very narrow rev band in my case. Hence with relaxed sedate driving in slow traffic it becames much more noticeable to me. See if you can identify what rpm you get your vibration and whether it occurs at the same rpm in different gears. Will be interested in what you find. We may or may not have the same issue?

I've got over 150 issues of Jaguar World to review to see if I can find any reference to the issue.

 

Interesting info ther NZxkr obout the 3.0 engine mounts. Might have to look into that a it more myself. It's also been suggested to me by a work colleague, that it could be a tired gearbox mount.
On my car, it's most noticeable in gear, however, I do still just feel the harshness at 1200rpm, however it's far less noticeable when the car's not in gear.
I may see if it's possible to just slacken the engine mounts, and re tighten them, and see if a difference is felt.

 

Are they solid or filled with something (oil, I suppose)? If the latter then maybe leaking.

However, if it happens in different gears, always about 1200rpm that must rule in & out various things.

 

surly you could check the engine mounts as i have seen instructed in a couple threads for the STR .
bonnet / hood open to view the engine .
apply firm braking .
and load the engine in reverse and drive .
have a friend or camera watch down the side of the engine bay
safely to the side.
the engine will rise a about 70mm if the engine mount is cooked.
this has worked for me .

 

Cheers for the info. I did try this a while ago.
I could see the engine rise, but couldn't be sure it was as much as 70mm, though it was certainly noticeable.
I did get under the car and couldn't see any oil around the mounts.
As it is a 2002 car, maybe the mounts have become tired, though it has only done 87,000 miles.

I may change the mounts anyway, however I've heard one of the mounts is easy to change, and the other is a bit of a pain.

 

Ok I've gone through 6 years of "Jaguar World" research and started to think I wasn't going to find an answer. I'm also a member of Jaguar Enthusiast club uk. They have a fantastic club magazine which is full of articles for each and every model of car. If you're not a member, I would suggest joining. Anyway I found what I was looking for in this magazine. If you have the magazine see June 2016,Vol 32 No6, see page 101.
Quote "It had one fault that once noticed I could not forget. There was a vibration through the throttle pedal"
The car concerned was also a 4.2 NA V8 and is what I assuming I'm experiencing with my car but the magazine didn't elaborate that the vibration was at 1200 rpm.
Quote "I visited my local dealership and the service manager could not feel it"

I also took my vehicle to the dealer 4 years ago and they couldn't feel it either. I guess you need to know what to you're looking/feeling for. This vibration isn't something where the engine mounts are going to leap up 70mm via testing. My car mileage is approx 56000km or 36000 miles.

Quote "After a call, I meet up with 2 engineers from Jaguar Cars Browns Lane Plant at the dealership with the service manager and the engineers arranged for the fitting of 3.0 litre engine mountings together with two short lengths of flexible exhaust pipe, fitted just below the cats. I believe the 3.0 litre engine mountings had a different resonance frequency, thus dampening the V8 vibration. This may have been carried out to other cars previously since there were Jaguar drawings for the exhaust modifications. The work was carried out and the vibration disappeared. The fault was rear in the UK but they knew of it in North America where more V8 cars had been sold" end of quote.

So what is not clear to me is what the part numbers are? I'll have to make more enquiries. Hopethe above makes sense. This is the path I'll be heading so will visit my dealer in due time once I sort out my leaking thermostat housing.
In the back of my mind I wonder if they had a bad batch of engine mounts?

 

So it seems others have noticed this as well. In a couple of weeks I have to do my oil change so I am going to poke around the motor mounts, exaust mounts etc. To see if anything looks or sounds suspiscious. I really don't want to change out good motor mounts for new ones and not fix anything. Surely someone on this forum had this and then changed something and it went away.

 

Some excellent research there NZxkr. Hopefully it's a start to being able to get to the bottom of this irritating little quirk.

 

I can live with changing engine mounts but having to cut into the exhaust to add some flexible exhaust piping is going to be a pain in the a.... Exactly where and how long, and where does one go to get the parts? I agree that someone else must have come across this issue . However if your car is running fantastic you wouldn't necessarily be trolling the forums???
I'll come back when I have more details.

 

When we come across items like this it would be nice and probably beneficial to the current Jaguar owners if they had people at Jaguar who had long term experience working at or with Jaguar whose job it was to support the customer base, not just until the warranty was up. Jaguar's selling point is the heritage so how about someone from Coventry jumping in once in a while to help guide your dedicated folks that keep the heritage alive. It would probably be a good marketing tool. I bet someone at Jag has some idea what might be going on with this resonation / vibration isue.

 

If what has been posted is correct then they have already figured it out as posted, with no more to add.

It's happened at least once in the 9 years I've been here. A bit longer and it may be more often.