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Anybody actually repaired and understood this trouble. It's a x358 xjr.
I have heard that the trouble could be the VVT housing not centered. And I also heard it's the two seal rings in the oil svivel in front that leak an the oil in the VVT housing is drained when shutdown.
Now I have worked my way into the VVT. I found 0.4mm exsentricity at the housing. That is a lot. 0,15 at the other side. Is this so much that the spring loaded locking pin inside the vvt won't lock the VVT when turned off because it doesn't fit into the locking hole?
I have no trouble correcting this and make it centered.
Or should I still take off the whole front engine cover and replace the two small plastic seal rings? Will it do anything for me? It's a lot of work and I would like to avoid it.
Well I tried to get any advice and info but half of the few who answer talk about the older style vvt.
So I desided to look into it myself when i already was doing some service to the car.
Now I am into the vvt itself and I have to admit, it was a lot of work. I am not scared of work but this was a bit much. Someone at Jaguar really likes hoses, coolers and connectors for hoses. But the most stupid thing is that they have made the Power steering pump bracket with mounting screws that goes into both the block and front cover. And to get that bracket off you have to take off the power steering pump, then the ac pump, then the ac pump bracket, then the power steering pump bracket...
So before I learned this i desided that I wanted to take out the vvt unit instead of correcting the excentricity of the VVT house. I may regret it now but its also a lot of work to take the cam covers off so when I was at it desided to just og ahead.
Now when I am into the VVT I see it may not have helped to correct the excentricity of the vvt, as it only does something for the outer housing itself, and there is lots of space and travel at the sealing parts in there. I doubt it would help, and it has nothing to do with the locking pin position or anything. The only thing is the rotary seals would maybe have an easyer job but thay are not super quality anyway.
I made a video and put it on youtube, take a look and discuss it here at the forum please.
Brilliant mechanical investigative skills! Thanks for the video, explains a lot. So on my car (XJ8, same engine), only the passenger side secondary tensioner was losing pressure and letting the short VVT timing chain become loose. (I had both cylinder head covers off to change the secondary tensioners, just in case they were bad) I found a solution, without having to tear into the engine a much as you have. I just ordered an "engine pre-luber", for $230 USD, which will build oil pressure in the engine before startup. Turn the key on without starting, and the pre-luber will pressurize the system in about 5-10 seconds and prevent the VVT rattle. I tested this idea a number of times by pulling the fuel pump fuse and cranking the engine 5-10 seconds to build up oil pressure, then reinserting the fuse and starting the engine. No rattle. There are videos on YouTube about this- search "Jaguar XK8 AutoEngineLube 1", by a gent named Richard Astley. He installed the engine pre-luber and it eliminated the VVT rattle on his car, with the 4.2 engine
. So on my car (XJ8, same engine), only the passenger side secondary tensioner was losing pressure and letting the short VVT timing chain become loose. (I had both cylinder head covers off to change the secondary tensioners, just in case they were bad)
OK, but would you say the "vvt" rattle dissapeared after you changed the secondary tensioner?
I have a feeling its this part that cause the "vvt" rattle. (until I learn something else)
I had a bad feeling about the sloppy tensioner you see in the forst Movie. So I took apart a new tensioner to learn how it Works.
Earlyer i thought it was just a cylinder that get pumped up With oil but now I see it has a valve and a small internal cylinder witch is supposed to be oilfilled and probably not collapse when engine is shut off.
I have a feeling the tensioners on my car dont work this way anymoore...
I replaced both of my secondary tensioners, the passenger side appeared to be not holding pressure, but the drivers side was. My passengers side was bleeding down, same as in your video. Changing both did nothing to change the rattle on startup though. I haven't had my passengers side valve cover off to recheck it. I did install an engine pre-luber I mentioned in my previous post, and that did completely eliminate the startup noise. It's completely silent now. I will remove my valve covers again soon, just to double check everything, but it's not such a priority now, as theres no more noise!
Brilliant mechanical investigative skills! Thanks for the video, explains a lot. So on my car (XJ8, same engine), only the passenger side secondary tensioner was losing pressure and letting the short VVT timing chain become loose. (I had both cylinder head covers off to change the secondary tensioners, just in case they were bad) I found a solution, without having to tear into the engine a much as you have. I just ordered an "engine pre-luber", for $230 USD, which will build oil pressure in the engine before startup. Turn the key on without starting, and the pre-luber will pressurize the system in about 5-10 seconds and prevent the VVT rattle. I tested this idea a number of times by pulling the fuel pump fuse and cranking the engine 5-10 seconds to build up oil pressure, then reinserting the fuse and starting the engine. No rattle. There are videos on YouTube about this- search "Jaguar XK8 AutoEngineLube 1", by a gent named Richard Astley. He installed the engine pre-luber and it eliminated the VVT rattle on his car, with the 4.2 engine
Tankrr, Old-ish post I know, but whereabouts and which fuse do you pull to turn the engine over without it being resupplied with fuel, please?
Regards,
Ray
Hi - wondering if the OP found a resolution to this?
On my 2006 XJR, I get a consistent rattle for 1-2 seconds when starting from cold, sometimes even after 3-4hrs after it’s reached operating temps, so not entirely cold.
I’d have to pay a specialist to investigate, and unsure how best to understand if the issue is VVT or secondary (?) tensioners?
ive read a lack of concentricity of the VVT unit can cause issues, but don’t understand why the noise disappears when hot - surely concentricity would remain irrespective of temps?
Would failed tensioners be identified before checking VVT units?
I’ve had 2 engine oil changes in the past few months, including an engine decon treatment (warm oil flush with engine off) using genuine Jag oil filters.
Vvt rattle
