The DOHC V6?

I seized the cams on mine ... "refurbished" the journals using emery paper and a socket as a mandrel and put it back together ... fired on the first go and was still running smooth as silk seven years later.

 

That ties in with something I read regarding another contributing factor to the secondary tensioner & chain problems.

The firing order of a quad cam V8 is such that the stab loads on each camshaft as it opens the valves are not evenly spaced. Instead of being at regular 90 degree spacings, there is a burst of 3 stab loads close together, then an interval, then a single load, then another different length interval before the next set of 3.

These irregular 'stab' loads will be taken by the timing chains, so they are more likely to 'flutter' in an irregular pattern if the tensioners have problems, and this factor will also add to any existing tensioner problems, increasing the chance of breakage.

The 'flutter' on the secondary chains can be reduced with a higher engine speed, as the increased inertia of the valve gear smooths out the stab loads & reduces the chance of chain breakage on an engine with marginal tensioners.

The chain tensioners often fail at idle speed, where the stab loads & chain flutter are at their highest speeds. There have been recommendations to avoid slow idling after a cold start on engines with the older & more questionable tensioners.

 

I am putting together the parts list for all the parts.
I know I have an AJ26 engine, will the Lincoln LS parts (2001) for the AJ27 work? or do I have to call Jaguar.
Also I am pretty sure all the bolts on this car are grade 8.8 I am thinking of upgrading to 10.9 bolts.
McMaster-Carr
or 12.9
McMaster-Carr

obviously not for cylinder head bolts.

 

Roger, why not just buy new 8.8, I think the reason is because they're not as likely to strip threads completely, just a little, it's alloy heads and block after all, and once you get to the torque readings you'll understand there's just no point, we're taking 10/20N/m - very light torque.

I think the cam covers are Jag specific, (orange and grey) possibly the two timing cover gaskets. As far as the timing parts wasn't there a list of Ford/Jag crossover part numbers kicking around the forum? Testpoint will know...

As for head bolts, as plums nudged me, get them from the local LandRover dealer, order 06' 4.2 supercharged RangeRover head bolts, along with this get an M12 Ribe socket to nut them up they're the upgraded later bolts, not torx.
Jaguar want £9 each, LR are £1.50 each, you get the saving, buy a beer on me

Just so you know, the engine is set/timed at 45 degrees after tdc.

 

Hi Sean,
I just put new valve cover gaskets on, and yes they are grey and orange.
I did find the list for the Lincoln parts and will be creating a spreadsheet, but will they fit an earlier engine.
As for the bolts, I'm **** and some of these bolts look cheap, I have access to and use metric screws and bolts for the work I do, so I figured whats a few more screw boxes in the screw cabinet. Also I have all the wrenches for SHCS.
The head bolts can be reused as the heads have never been off.
Also I like the idea of getting the best price for things and am looking at the best place to buy the multiple parts I need.
I figure I'm going to be over $1000 into this so ever penny counts.

 

Stab loads? I think you're talking about wave forms and amplitude. We can get into the maths of it, but the main point is they fail on startup.

These engines are inherently balanced to run as smoothly as possible, they fire in pairs, almost. They're not a Chevi pushrod.
A healthy engine timing system on these does not allow your flutter suggestion, only when a tensioner is broken.
A lot of folklore chatted about these engines, if in any doubt about the tensioners, change them the way Jaguar have done, after all it's like driving around with a grenade strapped to it, one day plastic will fail....

 

Mate try a full rebuild heads & bottom end - £2000+ ($3000) in parts alone, without polish and port time and rebuild time....good job you can do the job, what would it cost at a decent shop?

I'd go with new head bolts at the price I mentioned, they're stretch bolts and can shear...remember to turn them in to the lower quoted torque setting range, e.g. 8/10Nm use the 8, not 10, that's for new bolts.

Seen this?
http://www.ebay.com/itm/Jaguar-3-2-3...06461b&vxp=mtr

 

major jealousy !!!

I'll get the new head bolts..

Last time I did the chains it cost $2800.00 in 2008

 

BTW, rockauto has the head bolts listed under Jaguar for the Lincoln LS 3.9L which is the same block/head.

Victor Reinz for $48/engine set.

 

Hi Plums,
Do the Lincoln LS timing chain components work on a 98 AJ26 engine?

 

I think I should have phrased it differently...

It was not a criticism of the refinement of the Jag engines, just that from a mathematical point of view the firing order of any quad-cam cross-plane crank V8 does not produce an evenly-spaced sequence of valve opening actuations at regular-spaced intervals.

That's not a complaint, just a mathematical characteristic of the engine layout. The same principle applied to the first quad-cam BMW V8's introduced in 1992, but since these had double-row duplex timing chains then they were less prone to snapping if the tensioners were weak.

I once owned a 1993 E34 BMW 540i with 80k miles on it & put another 50k miles on it. It was the replacement Alusil engine block & there were never any inherent valve train problems with that engine design as it used double-row chains. It was one of the best engines I've ever had-the exhaust manifolds were thin-walled stainless steel tubular designs that were a joy to just look at, and the hydraulic lifters made for a quiet engine with no tapping or knocking noises.

The Jag V8 engine is also a great design with the same specific power & torque outputs, but unfortunately the early versions were compromised by production & manufacturing decisions. So the good work of the designers was undone in the beginning by production decisions.

The ZF gearbox problems were not Jaguar's doing, but since they were combined in the same car with an engine that had 'teething troubles' in the early versions, then the X308's reputation took a beating.

The big problems that afflicted the early X308 Jags (Nikasil, forward clutch failure in the 5-speed ZF autoboxes) also happened to BMW's way back in the early/mid 90's, apart from the chain tensioner problems.

The stab load refers to the fact that each time the cam lobe opens the valve, it puts the chain under tension. Because of the shape of the cam profile, it produces a stab load on the camshaft that is driven by the chain, so the chain will feel this load as well.

As you rightly say, with working tensioners the chain will not flutter-this is a relative term anyway, but each time a valve is actuated the chain will tension as it takes the load of the cam lobe opening the valve, and then de-tension again when the valve has closed.

So the chain is constantly tensioning & de-tensioning internally, which is fine if it's held rigid externally by serviceable tensioners.

The problems only happen with failing tensioners, as the chain will not be held rigid as it tensions & then de-tensions each time a valve opens & closes. Since the inertia of the valve train at idle speed is low, the relative amplitude of the chain stresses is greater than if the engine speed is high. The inertial energy of a fast-moving valve train will be great enough to keep the chains firm enough at high engine speeds with weak tensioners.

The smoothest engine of the lot is still the straight-six (and V12) as it's mathematically perfectly balanced & highly musical, producing odd harmonics that the human ear perceives as 'nice'

 

Good Post Red,
The manual I got for the timing chain from blackonyx is for an XJ8, I have an XJR the trans is different, I cannot see an arrow on the flex plate, come to that I'm not even sure if I'm looking at the flex plate, please can some one guide me, I'm trying to get the crank pulley off

 

It depends.

You have to be careful of which year of LS that you look at for each system.

It would be better to go into the Jaguar part of the catalog for the correct year and let their database pull up the right parts. If a part number fits, their system always charges the same price no matter what car you tell them you are buying for.

Unlike *cough* JLR *cough*

 

The pin is the same hole as the crank position sensor, you remove the sensor and install the tool.

BUT ... do NOT use the tool to hold the crank while undoing the pulley bolt, you WILL bend the flex plate. Use a strap wrench on the OD of the balancer. Install the tool *after* the removal to ensure that you do not bump up against it.

Or my personal favourite ... breaker bar and starter bump. An impact will work as well.

 

The difference between passenger V8 and racing V8 firing order has to do with the requirements with respect to exhaust layout on two banks. You can have an even fire V8, but at the cost of the bag of snakes exhaust layout seen on F1 V8's ala Cosworth.

As a result, you get the uneven cam lobe arrangement.

That's the simple version.

 

OK I found the cover, I can see the arrow, I see square holes in a sheet steel plate, ,Someone posted putting a prybar in to hold the flex plate if you do not have the tool, I'm not happy about using a prybar, and do not want to wait for the tool.. hmmmm what to do?

 

Cross posted ... see post above.

 

Plums, you're a godsend, I was thinking exactly that, and did not know how to move forward. It looked to flimsy, and everyone is saying what a b***h the crank pulley is to remove. OK now how to get a strap wrench to fit?

 

Don't know about the strap wrench, but it has been described previously. Usually by Motorcarman. Also read about the collet that is involved if it applies to the AJ26. That one just requires some taps with a hammer while applying pressure on the other diametrically opposed side to 'walk' the balancer off the crank.

Some people use webbing straps in lieu of the strap wrench. Pretty much the same idea as the strap wrench just tightens agains the webbing.

 

The racing V8's frequently use the flat plane crank for high rpm, but this reduces engine smoothness so the cross-plane crank with well-placed counterweights is used for passenger cars to give more refinement, giving rise to the assymetrical valve opening sequence.