Hi EsRay,

I can't make any sense of this. First of all, there is no, or at least should be no communication between the transmission oil and the engine exhaust.

Secondly, while the earlier ZF 5HP24 transmission used in the X100 and X308 was known for A Drum failure, I don't recall other members reporting this problem on the ZF 6HP26 used in the X350s.

There are a number of malfunctions that can cause the ECM/TCM to electronically lock the transmission in 3rd gear (Limp Mode or Limp Home Mode) such as engine misfires, etc., but it sounds as though your mechanic is claiming this was a hydro-mechanical fault inside the transmission.

Frankly, I don't understand or believe the explanation, but I'm happy your Jaguar is behaving properly again!

Cheers,

Don

 

Hello Don,
I do not understand it either! However, my mechanic is Syrian and I struggle to understand pretty much everything he says......
He is telling me that a serious transmission problem (a cracked Drum) was causing the trans faults (I was shown a/the cracked Drum) and also causing the plume of smoke from my exhaust. He has replaced my transmission with a recon unit for £1,200 and my car no longer smokes or tries to pull away of it's own accord at lights. As a very welcome by-product, it is running beautifully AT THIS TIME!
My (albeit inferior understanding) is that the engine and transmission are linked via the Adaptive Shift Mode etc, etc so it comes as no surprise that there is some link between a faulty transmission and poor engine behaviour?
Who knows - I certainly don't!

 

Well Don, I am now aware of my own prescience!
This morning I had to crawl home with a red light after dropping my wife at work. The front end of my Jaguar has collapsed and will not come back up again. Air suspension fault, car too low. Red light. Very, very loud hissing noise front right side as compressor struggles but fails to lift her. Front wheels rubbing against the wheel arches as I turned into my parking space!
Question, please: have both my front air-shocks failed simultaneously, or could this be a compressor leak (my car is L/H drive if that makes any difference to compressor location)?
Don, just found your post re: if one side of front leaks, both go down.......

 

Hi EsRay!

So sorry to hear about your suspension problem. Yes, on your 2005 there is only one ride height sensor, so both front air springs receive the same air supply. If one air spring leaks, both air springs will lower.

You can check the air hose and fitting on the top of the air spring (under the hood/bonnet). If you're lucky, that's where the leak is. If you're not so lucky, the hissing will be coming from the wheel well, indicating a ruptured air bladder and necessitating a new or rebuilt air spring/shock absorber unit.

Please keep us informed!

Cheers,

Don

 

Thanks Don.
Interestingly, I jacked up the leaking side (basically just taking the weight off of the suspension on that side) and started the engine; the opposite shock immediately inflated and rose to normal height. No doubt if I lower the affected side back fully onto its wheel, I will hear the merry sound of air peeing out of the affected bladder (best place for it to do so) and both sides will sink again!
At least I now know that I have only one to replace (for the moment)!!

 

Don, please forgive me for being a pain and I do realise that this subject is far away from the subject of these posts! However, I have read somewhere on this forum someone opining that one does not need to replace (say) both front Air-Shocks because they are basically static and controlled by the array of sensors? I can understand this opinion, but what I am unable to factor in is does one not also buy an oil-filled shock within the replacement Air-Shock ( I may well have this wrong), and if so, does this oil-filled, ECATS-enabled shock deteriorate with age?

 

Hi EsRay,

The air spring and shock absorber are one single, combined unit and cannot be replaced separately. The original units were made by Bilstein. In the past, it has been possible to purchase a single rebuilt Bilstein unit. Arnott Industries was one company that rebuilt them. However, the last time I checked, Arnott no longer offered the rebuilt units. Some other companies may now be doing so, and hopefully another member will let us know, but if not, use the Advanced Search function under the Search tab above to search the forum for posts on this topic.

To better understand the air spring/shock absorber unit, you can download the Air Suspension section of the Dealer Training manual here:

X350 Air Suspension Manual

And you can find a summary of the air suspension system here:

Air Suspension & ECATS System Summary: Components & Operation

Cheers,

Don

 

Hello EsRay, you are right, the term air-shock is technically not fully exact, or you should call all conventional suspensions steel-shocks ��
In fact only the spring is an air spring, which has some theoretical, and sometimes even real, advantages over a conventional spiral steel spring.
An air spring has a strongly progressive characteristic force curve, so it can be soft and comfortable around regular ride height, but when it is compressed far it becomes a lot harder due to the exponential increase of pressure in the bladder, thus preventing the strut to hit the bottom.

On steel springs a similar effect is reached by varying the coil distance over the length of the spring. When the spring compresses the close coils are laying on each other and are thereby deactivated. Less active coils result in an increased spring stiffness, creating a similar effect
In my opinion it primarily is much easier to realize a ride level adjustment with air springs than with a complicated mechanical adjustment. Also dynamic adjustment is easily possible, for example by increasing pressure in the outside struts when cornering, effectively reducing the leaning to the outside. A dynamic control like this would be quite challenging with any mechanical system on steel springs..

The damping element at the core of the "air-struts" is a conventional hydraulic damper like in any strut with a steel spring and is subject to the same wear and aging as every hydraulic damper.

 

The air spring part of the unit can never "sack-out" like a steel coil can. That's why with coils it used to always be recommended that if one coil breaks, then both have to be replaced.However that is not the case nowadays with the much greater precision of manufacture. Anyway, if your car is on reasonable miles, it is unlikely the shock-absorber part of the unit is worn out, so if it were me, I'd replace the one failed unit. There are companies still replacing the air diaphragms, here is one in the UK, but I have no personal experience of their rebuilds.

https://airdominance.co.uk/

The other thing to do is look for a used unit on the internet.
Here's an OEM Bilstein unit: -

https://www.britishparts.co.uk/jagua...r-spring-p6161

Here's an aftermarket unit (country of origin unknown)
https://www.ebay.co.uk/itm/C2C41352-...-/272584131940

You are guaranteed that the Bilstein unit will have the facility to support CATS Hard-Soft switching, but you'd need to check the others.

 

Fraser,
Thank you for your post. I have trolled the internet looking at these damned air-shocks. Obviously the Chinese replacements are the cheapest. I realise that this is unfair of me, but have you had experience of, or heard of anyone using them, please? I know you get what you pay for, but (after replacing all the bushes and control arms and fitting a recon transmission) I really do not want to afford to buy a 'top-shock' for one side of the front, only to buy another top shock for the other 3 months down the road? I have been unsuccessful in finding out whether or not these Chinese shocks support CATS and in my opinion (for what it is worth) there seems little point in sticking with Air Suspension without CATS? Might as well bite the bullet and Coil Over without CATS (I think)?
But really, I don't know what I am talking about - Even though I have read all of Don's posts on this subject thoroughly?
So can I impinge on you and other 'Jaguar Veterans' to give some no-comeback advice?
Don't spare me - If I really need to pay top dollar to keep CATS please tell me that. Then I can decide how important that is/is not to me? A big part of my problem with this is that I am in Dubai, so I cannot exchange my 'shot' shock for rebuild at a reasonable shipping cost (I looked at and liked the RMT Shocks but the shipping back of my shot shock was prohibitive and without doing so invalidated all guarantees)?

If I were Arnott, I would offer a kit that replaces just the front air-shocks with Coil-Overs and without error messages to bring our cars into line with the latest (hideously swollen) XJ's!

 

Replacing the worn out front (or rear) stock struts with Arnott designed new front struts gives you the best of both worlds. A new shock like you would get with a coil conversion kit PLUS the auto leveling and the smooth luxury ride that air struts provide - and without an error code.

As many long time forum members know - Arnott remanufactured Jag XJ struts until about 2016. Unfortunately, many of the cores we started receiving were in such bad shape that they failed our tests and had to be discarded. Many of the internal CATS shocks as well and top and bottom mounts just couldn't be rebuilt. This isn't surprising - X350s are all over ten years old and X358 are getting there.

The Arnott designed new air struts provide an excellent alternative. All new components are used including a brand new, custom valved, shock that adapts to a drivers style. We also use a new machined top which is much thicker and sturdier than the stamped steel OE, new bump stop, improved seals, a new tight bottom clevis and new protective aluminum can and dust boot to protect the assembly.

Reviews including on this forum have been overwhelmingly positive. Most don't even care that the active damping is gone because they have a brand new shock, with a new car ride, instead of a worn damper with an unknown number of miles.

Plus, like all Arnott products, new and reman, they come with a limited lifetime warranty (for as long as you own the car).


Check them out: https://www.arnottindustries.com/pro...ries/x350/2007

 

From what I am able to gather, my mechanic is saying that a drum in the trans was cracked nearly in half and when hot this crack would open and jam the drum. The result of this (he tells me) was like someone changing down from 5th to 1st gear at 120 kph! He says that this event was what caused the huge plume of white/grey smoke from my exhaust...….