Timing Chain Tensioners 4.0L

[xjscharlie]

Hello Folks,
On removal of a cam cover is it possible to check that the tensioners are the latest metal type?
I've been told that the tensioners on my 4.0L have been changed out but have no documentation to support that and i would certainly like to know. Any advice appreciated. Charlie.

[J44EAG]

Shot answer, yes, Charlie.

See this post from the well known Barke Buster on the subject of tensioner replacement. Sadly, it would appear that Vince remotely hosted the images...possibly on Photo Bucket which now charge for viewing. viewtopic.php?f=86&t=3324

That said though, I think you will find the text helpful.

Mike K

[xjscharlie]

Many thanx. I have an ongoing VVT tapping noise which goes off when the engine warms up~trying to cure this by flushing. Other than that the engine is quiet so will perhaps just keep my ear to it rather than taking it apart as i only do local mileages. Rgds. Charlie.

[J44EAG]

VVT units do wear. My V8 started tapping at 90K miles. I flushed and oil changed several times. It improved a bit but at the end of the day I concluded that car was heading towards needing new VVT units.

Mike

[RichardSEL]

I've had three XJ8 -- 4.0L LWB (didn't change tensioners as I was offered money for it before I could get on with it);
a 3.2L Sport that'd belonged to an enthusiast who'd had the tensioners changed but there was no receipt (so I wasted £40 to a specialist just to have a look) And my current Exec that cost me £420 to have them changed. The exec's were green plastic both of them had already split along the plastic's length so were ready to give way.

Real answer is to have them done together with the ATF and filter. Then you know you've proofed your car from at least those two that otherwise will eventually come up and bite you in some far away place -- such as East Cheam...

[xjscharlie]

Quite prepared to go for VVT changeout if the tapping does'nt stop. Its a bit of a mystery why the tapping stops on warm up then will restart when the engine cools down. WRT the timing chain tensioners~thought of going in there with a borescope camera either via the coil inspection cover or the breather aperture on the RB cam cover just to see what can be seen, if anything.

[J44EAG]

Essentially wear in the VVT unit and oil flow due to cold oil flow resistance is a prime cause. I can`t remember if the V8 has gauze filters within the VVT units but there may be a flow restriction due to sludge build up. If the car has the early (three generations of breakable plastic tensioners before the 4.2 ali units came on the scene), then there is the distinct possibility that the top slipper plate , or indeed the molded in lower slipper,may be disintegrating. In extreme cases, the slipper breaks off and you have metal to metal contact between the chain and the tensioner metal plate. This will lead to noise which disappears as the engine warms. Plastic tensioners develop splits in their bodies. Eventually the whole lot fails and causes an internal engine coronary. Bent valves, holes in pistons and an engine rebuild.

If a car doesn`t come to you with documentary evidence that ali tensioners have been fitted, then it is imperative to lift the cam covers and see what is fitted. That can never be seen as a waste of time or money given that an engine is around a £7k job to repair or replace.

I`ve tried inserting an endoscope along the underside of the near side cover which has the oil filler up-stand. Obstructions within the engine stop the endoscope going any distance. Cover removal is the only option.

Mike

[xjscharlie]

Many thanx. The basis for my concern was that i have no documentary evidence and this is certainly a case where "better safe than sorry" applies as you alluded to; so intend to have a look. Will advise.
WRT the VVT tapping issue someone suggested removing the VVT solenoids and giving the VVT's a good blast out down the orifices with pressurized brake cleaner or carbon tet. just before a flush/oil change. Have you heard of this being done? I've done this on oil pumps in the past..Rgds Charlie.

[J44EAG]

I can`t say I have, Charlie.

Obviously what you have suggested is not "recommended " by Jaguar so in such a case, necessity becomes the mother of invention. If it works, you will be happy. If not, then all you have probably lost is a bit of time. Provided you were to oil change immediately after you have tried your idea, then I really can`t see how you can do much harm. What you will be trying is a spirit clean which will flash off to atmosphere in seconds leaving just fumes. These will be absorbed in the oil and further disappear in a few minutes. Any risk of explosion is probably minimal.

Carbon Tet!! We used to buy that in the chemist as kids. No restrictions then. Now it will be a restricted substance and you will be hard pressed to obtain it anywhere. It is nasty stuff which can build up on the liver. We used to use it to clean our model railway lines. No protective gloves or anything. Just a wad of cotton wool with the Tet in a brown chemist glass bottle. All it said on the label was "Carbon Tetra-chloride". Nothing else. No "elfin saftey" warnings or any user advice. Now I use acetone as a cleaner. Far less toxic but never the less appropriate grade of gloves should be worn. Failure to use gloves when using the stuff at one of the jobs I had, meant instant dismissal!

My personal opinion about this VVT issue is that no part lasts for ever. Wear issues are known with these V8 VVT units and I can`t help feeling you might be grasping at straws in the hope of a quick fix. I understand it is worn bevel gears inside the units that cause the noise.

Mike

[xjscharlie]

Thanx Mike the brake cleaner i have smells like a cross between cellulose thinners and acetone. If it does'nt work the n i'll be looking at changing out the VVT units. I've never done this, only seen it done on UTube, so the only way i would undertake it is if someone was supervising me who had done it before. The daft thing is that once the tapping stops the engine is whisper quiet, no chain noises or scraping or rattles.

[J44EAG]

What grade oil are you using, Charlie?

Mike

[xjscharlie]

After the last flush 5W30 semi synthetic with a litre of TQF and a can of Wynns oil additive. This will be there until the next (&last) flush.