A friend had a secondary tensioner go on 2001 XK8. He got lucky in that it happened on start-up instead of at speed so he avoided any valve/piston/cylinder damage. Although it only broke on one side he's going ahead and changing out both secondary and primary tensioners and all the chains along with all new seals and gaskets.

He bought one of the simpler tool kits for doing the secondary's as he owns and runs a engine machine shop an has pretty much everything else but wanted the camshaft locking bars to avoid any potential timing issues.


However, we can't figure out what the two metal shim pieces that came in the kit are for. Anyone every used them for anything except a paper weight and are they usable on a 4.0 engine?

Also anything really tricky he should be on watch against as he's never had to tear into a Jag or Lincoln 4.0/3.9 before. He has been so far pretty impressed with the overall engineering he's run into and since his car has a tad over 100,000 miles he knows the tensioner failure is his fault and not Jags.

At any rate anyone who has some advice...jump in as I'm getting to the point where I'll have to do mine as well since my '99 is just now getting to 65,000 miles even though it's as quiet as a church mouse at the moment<G>

 

Are the shims shaped like a T?

 

RDM, it would be better if you posted this in the forum for your car. (X100) 1996-2006.


Engines for the X350/X358 cars of 2003-2009 don't have any cam chain tensioner problems as this was fixed in the 4.2 litre cars. The 4 litre V8s had cam chain tensioner problems until very late in their production life. This was due to somebody in Ford thinking plastic was a suitable material for a tensioner body ! Eventually common sense prevailed and later ones are metal.

 

Thanks Fraser as I wasn't paying attention and should have done as you suggested.

A side note however in that Ford had nothing to do with the engineering of this motor as it was clean sheet design of Jaguars and was adopted for use in several Ford models here in the states (retro-T-Bird and Lincoln LS are two that come to mind. Although Ford had started purchasing Jaguar in 1990 it's initial investment was additional money for development of new products, access to parts international parts bin and supplier network and the availability of Ford's more modern (by the standards of the 90's) CAD systems.

The important difference, at least to me, in the design of the secondary tensioners is the switch from a mechanical spring loaded tensioner plunger to the much softer hydraulic powered plunger of the aluminum bodied tensioners. They both continued the use of a plastic 'guide' section on which the cam chains rode .Yes the body of the tensioner was now aluminum but the part that normally broke, the 'guide' is still plastic of some sort. The old style used a mechanical spring loaded plunger that made the chain pressure on the plastic guide considerable higher than the Gen 3 tensioners.

 

You can read in the website link below why DOHC V8s are difficult with cam chain tensioners: -


THE JAGUAR AJ-V8 ENGINE / AJ6 Engineering


BTW, you're right on Jaguar being the designers not Ford. So a black mark to the Jaguar engineer who thought a plastic tensioner would be OK in the location it is placed. Mind you, who thought they could get away with Nikasil ? All they had to do was ask around a few BMW agents.

 

The owner/operator of the machine shop that replaced all the tensioners in a friends 2001 XK8 (100,000+ miles) after it jumped a tooth last week told me he had no bones to pick with the way in which the Jaguar engineers designed and built that motor. He's been rebuilding Ford, GM, and Mopar motors for decades along with various Toyota and Nissan's as well and think's that Jag did a damn good job of it by comparison.

In the one 4.0 he just completed one of the secondary tensioners had previously been replaced with the gen 3 variety but whoever did it didn't bother to do any of the other either primary or secondary ones. Someone either did the cheapest possible fix in order to sell the car or an unlucky previous owner got scammed big time by the shop that did the job.

In any case the other secondary tensioner mad it over 100,000 miles as did the primary tensioners (both cracked and beginning to drop chunks into the pan) and their chains. I got a good look at the parts including the previously installed gen 3 tensioner as well as the original style plastic one and there is a noticeable difference in the amount of force applied by the tensioners plunger against the slipper chain's slipper piece.

I'll ask him if he noticed any deterioration in the cylinder walls but I'm not sure if the 2001 4.0's still used Nikasil or if he had to even take the heads off since there had been no valve to piston contact. He did say that the job was a relatively easy one but he has decades of experience and plenty of tools which most of us don't have access to<G>

 

Interesting post !


When I challenged a Jaguar engineer at the 1998 Motor Show in Birmingham about the Nikasil issue, I was told all engines were now fitted with steel liners, but I don't know the exact VIN when the change went into cars going on sale. However, a 2001 engine is very unlikely to have Nikasil. In fact, Nikasil engines that have survived are likely to last as sulphur in petrol was removed in the early 2000s. The cam chain tensioners took much longer to sort out. I agree they are a fine engine, the 4.2 even finer.


Problem here in the UK is the dreadful price of petrol, and car tax that favours diesels.

 

My 2001 XJ8 had a Nikasil engine. I had over 140K miles on it when I sold it and it used no oil and ran like a scalded dog to 6850 RPM in sport mode. I've heard of people tearing down these engines at well over 100K miles and the cylinder walls still having the cross hatch marks from when they were assembled. Nikasil was harder, slipperier and lighter than steel. The Sulphur in cheap fuel did it in.

 

I didn't see an answer to the t shaped wedges- they are for the lower tensioners, you put them in between the chain rails and the tensioner while you set the cam timing- it's in the procedures.

 

[QUOTE=
At any rate anyone who has some advice...jump in as I'm getting to the point where I'll have to do mine as well since my '99 is just now getting to 65,000 miles even though it's as quiet as a church mouse at the moment[/QUOTE]


Mine too was as quiet as a church mouse. These were replaced right after I bought the car at 55,000 miles, I did the whole kit as my mechanic said if I was going in there, do everything. I was lucky... These are just two of the shots I took of the replaced parts. They were all scary.

 

I changed the secondary tensioners on my 2002 (82k mi) yesterday. Both had substantial cracks (completely through the lettered flat spot). I was astonished how well they held together even when cracked to that extent. Maybe I'm just lucky.

Sorry, cant answer the question though, used the zip tie method.

 

The wedges are for the primary chain tensioner-to-blade to make the chain DEAD TIGHT instead of relying on spring or hydraulic pressure for timing lockdown. The new lower tensioners are of the RATCHET style and can have some slack before the next tooth is engaged to keep it tight.

The oil pressure will keep the piston tight to the blade if the ratchet is at somewhere less than the next tooth, but the engine needs to be running for oil pressure.

Download my copy of the Engine Repair Course 168 to see the use of all the special tools for the V8 engine.

bob