I have found myself with a high-mileage X350 XJ6 with a few troubles.

The biggest problem is terrible ride quality. When I got it, the ride quality was poor, with quite a bit of vibration, but not obviously so. It went into a specialist where it sat for weeks before being told it was totally knackered, but then he tried to buy it off me and backtracked on the most negative comments so wasn't particularly sure he was being entirely truthful. It then went into my local, trusted non-specialist where he said it was broadly fine, changed the front discs and pads and rear track rod ends (at great expense...), and said it would need an alignment to sort the ride quality out once and for all.

However, the ride quality has deteriorated severely and it is now extremely hard and fidgety. I'm fairly sure this is down to the o/s/r being about an inch or so lower than the n/s/r. I have done the soapy water test on compressor fittings and top of strut, with no evidence of leaks. I do not have a warning light on the dash. I pulled the electrical connector and cleaned it out (and this did trip a warning, so the warning system does work). I've disconnected the battery, with no luck. So a bit out of ideas.

My two questions:
- Would a ride height sensor issue trip a warning? I would have thought it would have given it is an electrical component, but it would perhaps be an obvious problem for a ride height issue?
- Is there some sort of calibration that might need to be done?

Various other issues to be resolved but only after the suspension is fixed ...

- Key has stopped working, battery change didn't help.
- Oil leak of some description, think it is gearbox oil, quite a bit of evidence of old leaks though so could be engine oil as well.
- Coolant leak, there is some pinkness around the waterpump.

 

Can you describe what do you mean by bad ride quality? Does it vibrate on smooth roads? Does it not handle bumps well? etc?

1-How are your rims and tires? Are they bent? Does the car vibrate when braking (if yes, pads and rotors are culprits)?

2- Did this problem get progressively worse or is it all of a sudden? Have you taken a look at suspension bushings?

 

I haven't had the car long and haven't done many miles in it. When I first got it, it was more of a constant vibration and fidgety ride. I took the front right caliper apart, cleaned and greased it and the brakes have been replaced, as I thought it was a sticking caliper and the front discs were in poor shape. It is now more of a fidgety, jittery ride, crashing over imperfections, even very minor ones on smooth roads. I'm fairly certain it is a very firm o/s/r strut that is causing this, as if there is no give in the strut at all. The tyres are old, not sure if wheels are bent or out of balance - I was planning on getting alignment done and wheels balanced, but it isn't a constant or rhythmic vibration, hence why I don't think it is due to tyres or out of balance wheels, and don't want to spend more money on things until I've diagnosed the suspension fault causing the low o/s/r. I've been round the bushes and they look fine, and my mechanic didn't identify any that need replaced either.

 

If the vibration is only under acceleration; consider the tranny mount or engine mount.

 

The vibration is primarily felt when hitting imperfections in the road surface, and is not linked to engine speed. As said, surely it is down to the firm and low o/s/r suspension, which is the issue I am presently trying to diagnose before working out if it is due to anything else

 

" .... and low o/s/r suspension"

Pray, just what is this???

(If you have the OE air struts, leaks are 95% at the bladder, not the top hat. V difficult to find with soapy water. Lots (and lots) of threads on how to diagnose and fix in this forum. Low ride height, speedo display faults, etc generally leaking strut(s), with compressor unable to keep up. Also, give a look and make sure you don't have some chinese struts in there. They're worthless, IMHO...)

 

Sorry, o/s/r means off side rear i.e. driver side rear.
Would a leak at the bladder give a suspension warning light?

 

Yeah - definitely. Most common cause...

(The air struts are a bit like tires. Both time and mileage trigger need to replace them. Bladder is rubber, and tends to micro crack and leak. This forum is the right place to get it sorted, esp for a DIY'er such as yourself. New air struts are expensive. Set of decent steel spring replacements are one cost effective alternative. Buy from a proven supplier if you go this route...)

Hope this helps!

 

The air suspension has CATS, (Computer Active Technology Suspension). This essentially takes readings from various sensors around the car whilst it is moving and alters damper settings from Hard to Soft, and vice versa to assist the car in its various modes like cornering and braking. The default is Hard. Soft is invoked by supplying a voltage to the dampers. In normal cruise the system will set all four dampers to Soft. If a suspension-related fault occurs the system reverts to Hard. This will make the ride noticeably harder and less comfortable. However this would normally be accompanied by a fault code and display on the message panel on the dash. From what you've said so far, you don't have a fault message, so it's puzzling, unless Charlie Allthumbs has been mucking about with the car and installed non-CATS suspension units.

 

This is what confuses me - if there is a leak, why is there no warning message? If I pull the electrical connector from the top of the strut, it does force a warning message.

I have been offered a pretty cheap second hand strut in working condition that might be worth chucking on to see if that sorts it. Otherwise, I am at a loss.

 

Any suspension codes? They start with a C. And only JLR reader can show them to you

 

Before you spend any money check that none of the ride height sensors have become displaced; the fixing clips can break, if so the system will allow the suspension to drop without registering a fault. A poor battery can also cause a harsh ride, but is usually accompanied by random warning lights and fault codes which will clear when it’s replaced by a good battery.
Good fortune with it; the 3.0 is a really good durable car, so don’t worry about the mileage.

 

Sadly I do not have an appropriate code reader, my one won't read suspension codes.

 

Maybe take the car to a specialist with the right code reader or buy one like icarsoft (I own LR II BTW) yourself