If I’m understanding you correctly, do you mean when you’re rotating the crankshaft clockwise (the correct direction starring at the front of the engine) by hand, have you turned the crankshaft counterclockwise as well??

If you have turned the crankshaft counterclockwise, that’s a definite issue. It’s all meant to spin in one direction only and timing will likely be compromised.

If I misunderstood you in your wording, sorry!

 

You are correct. When I tried to move piston to TDC I was turning crankshaft clockwise and also counterclockwise to position piston as accurate as possible. This way I identified click sound. And yes, it clicks only once per rotation direction change = it isn't clicking constantly when turning crankshaft in one direction.

Tomorrow I will check "clicking" presence on my second car with "healthy" engine.

 

Addicted2boost brings up a point I am NOT sure about?

On the later 5.0 engines you DO NOT rotate them in ANY direction except clockwise! Or damage will result according to Jaguar. I have yet to see exactly what that damage is but I don't plan to find out on my car!
You don't have the 5.0L so not sure that is a problem but I "think" that's what Addicted2boost is saying?

But at this point I would be removing cam covers and planning on a full rebuild of the tensioner system.
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If I recall correctly, the workshop manual warns not to rotate crankshaft counter clockwise as it can cause bearing damage.

 

I am not doing full turns. Clockwise just few degrees and then back.

 

Today I removed RH cover and inspected secondary (top) tensioner. There is missing plastic element which is pushing against chain thus in my case chain is running directly on metal. Wondering if this could be source of knocking sound.

I also removed front engine cover and inspected primary chains and tensioners. Tensioners are loose (no oil) but when removed and inspected they seems to be perfectly tight - removal of "piston" and putting it back is compressing air and keeps a pressure. If I insert thin wire through the top of the piston and push spherical valve then it depressurizes. Chain guides and tensioner blades looks OK - not missing any plastics and not visible significant scratches (rails).

I also tried to rotate "healthy" engine on the other car clockwise and counterclockwise (few degrees) and there was also small play and some "clicks" but way smaller and silent.

Can you recommend any link with description how to inspect timing system? I am planning to upgrade it but would like to know what is wrong here and what is OK.

FYI - I was unable to remove crankshaft pulley with impact rachet thus I pre-heated pulley screw with gas-flame torch and then unscrew it quite easily with electric impact rachet.

Some pictures will follow.

 

 

These tensioners are not from my car!!!

Just FYI - cheap chinese (most probably FAI) tensioners after 40000km from S-type. Does anybody have similar experience? I am considering OEM timing kit only.

 

Rotating the engine CCW is just ‘ok‘ for a few degrees but I wouldn’t make it a habit. Without going into what I perceive as a dissertation on why it shouldn’t be turned CCW can be summed up as it’s all about the engine timing of both primary and secondary chains in relation to cams and crank position. It’s even more complex when you throw in the naturally aspirated VVT 4.0L engines as the intake sprockets can likely rotate CCW a good amount before the secondary chains begin to move. I know this hasn’t answered all the questions but, let’s use the KISS method and say, don’t rotate the engine CCW. 😂

 

Hi Zdicho,

I am following your journey with great interest. You've received great advice so far and have done great detective work yourself!

One thing to be aware of is that the crankshaft pulley is a harmonic damper with a rubber isolation core bonded between the central steel hub and the outer steel belt pulley. Using a torch on the crank bolt could potentially damage the rubber core, leading to failure of the damper. If, when you get it all back together, you have symptoms of damper failure like vibration or screeching sounds, it can be rebuilt by Dale Manufacturing or Damper Doctor, or you can usually find a good salvaged replacement on eBay.

Since you do not have the official Jaguar style harmonic damper holder to restrain the crank while removing and installing the crankshaft bolt, one method is to use a chain wrench around the pulley, padded by a section cut from the rubber drive belt (which you will probably want to replace as part of your work anyway). Another is to remove the bellhousing inspection plate and use a lever on the torque converter, but that method is tricky for one person if the car is not up on a lift.

BTW, the crankshaft bolt is torque-to-yield and should be replaced with a new one. Also, there is a thin rubber O-ring inside the bore of the harmonic balancer that helps prevent oil from leaking through the split in the locking cone. The O-ring should be replaced along with the crankshaft oil seal. Part numbers can be found at parts.jaguarlandroverclassic.com.

Cheers,

Don

 

Thank you for valuable remarks Don! Using a torch with caution is important. It is quite easy to heat only the bolt and keep pulley safe.

I understand that bolt should be replaced but there is a common practice to not to do that in case of X308 engines and there was never any issue with that. Bolts are from quality material and with massive thread. If you look at 5.0 engines then there is a bolt with fine thread and it is preffered to replace it with a new one.

 

i use a right angle impact and reuse the crank bolt never an issue

the cone locks it in good

 

How do you measure the torque with an impact gun?

I'm sure you know your tools, but I have two or three low-profile right-angle impact guns, and I don't think any of them is capable of applying more than 150 to 175 ft. lbs. of torque. This is a limitation of the low-profile right-angle guns.

The Jaguar specification for the crank bolt is 80 Nm / 59 ft. lbs. plus an additional 80 degrees of rotation, to result in an estimated torque application of 320 - 400 Nm / 236 - 295 ft. lbs. (see the attached TSB, thanks to motorcarman). The Workshop Manual gives the same torque-to-yield spec for the versions without the locking ring, plus a straight 375 Nm (276 ft. lbs.) spec for those with:






This is definitely sufficient torque to stretch and affect the metallurgical integrity of the M16 x 2.0 bolt. A 16 mm bolt is very close in diameter to a 5/8 in. bolt (0.6299 in. vs. 0.625 in.). The chart below shows the tensile stress (stretching force) applied to a plain, dry (unlubricated) high-grade 5/8 in. bolt when torqued. There are other factors that come into consideration, such as bolt finish (and resulting friction), lubrication, and thread pitch, but the order of magnitude of tension is always similar to this chart. You can see that at 250 ft. lbs. of torque, near the middle of the torque range specified by Jaguar, the bolt is subjected to 24,000 pounds of tension or tensile stress. That is 12 tons of tension! And at 276 ft. lbs. or the maximum spec. of 296 ft. lbs., the tensile stress is closer to 29,000 pounds. This is equivalent to suspending from the threads of the bolt a chain of seven complete Jaguar XJ8s at 4,000 pounds each!





Below is a photo showing an original bolt I removed from an AJ27 engine (at left) held heads-to-tails with a new bolt from Jaguar. This is not a scientific demonstration, but it is obvious from the light shining through the gap that this particular original bolt is longer than this particular new bolt. This could simply be due to manufacturing tolerances. Or, it could indicate that the old bolt was physically stretched by the tremendous tensile stress to which it was subjected, which would be evidence of the deformation described in the technical literature, and the reason we are told that torque-to-yield bolts are "single use" fasteners:



The new bolts come from Jaguar with threadlocker pre-applied (see bolt at right above), so if you are going to risk re-using the old bolt, you should definitely clean the bolt and crank threads (with a tap and solvent), dry, and apply threadlocker before reinstalling the bolt.

The locking cone or "split collet" applies wedging force between the crankshaft and damper pulley to prevent the pulley from spinning on the crank when the bolt is properly torqued. The crank timing chain sprocket is located by a standard Woodruff key, but the damper pulley has no key and relies entirely on the split collet and the force applied by the bolt to prevent the pulley from spinning on the crank.

The split collet doesn't appear to do anything to increase the unthreading resistance for the bolt. Instead, to the extent that the collet does not push completely flush with the end of the crankshaft, its relatively thin outer rim presents less contact surface for the head of the bolt, and therefore less unthreading resistance. So a bolt that is inadequately torqued is not only more likely to loosen over time, but to also allow the pulley to spin on the crank.

There is at least one report from a member of the forums whose crankshaft threads were damaged by the use of an impact gun on the bolt. There are also reports from at least two members whose re-used crank bolts loosened over time, allowing the pulleys to spin.

It's natural to look for shortcuts to save time and money, but for most of us, the safest course is to trust that the Jaguar engineers had valid reasons for the procedures they prescribed.

Someone smart once said, "If you don't have time to do it right the first time, when will you have time to do it again?"

Cheers,

Don

 

Great information! If the Duchess ever requires that procedure....
it is definitely NEW bolt time for her!

 

Top notch post Don! Learn something new on this forum everyday.
I must say that crank shaft bolt sounds like a PIA getting it out and back in properly and I hope to never have to do it!
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Just to show what Don is talking about, here are some damaged cones (and crank nose) from poorly torqued crank pulley bolts.

The damage done had made this engine 'borderline'. Several attempts without locking and putting the torque spec onto the bolt led to crank damage.

The cone had partially melted, heat blued and picked up material from the crank nose meaning a custom cone had to be fabricated to clear the timing cover or the pulley would have wound into the timing cover.

You'll see "battery not charging" then things go south very quickly, engine temperature rockets and heads warp. Putting the torque on with an impact is the dumb move.....especially on supercharged cars - particularly when the air con is on and it's wide open throttle.

 

With engine parts it's pretty much a no brainer - OEM only. There is a large amount of info on replacing the timing on here, all I would say is take your time and order the bolts that fit the later secondary tensioners as reusing the old ones seals the oil gallery that feeds them to tension the chains.

 

Don B - thank you for fruitful overview! Always good to have such source of knowledge based on experience!

I was using impact wrench just to remove pulley. For tightening I am always using calibrated 400Nm professional torque key.

Regarding longer pulley bolt (used) shown on your photo I am wondering why it should be longer? Is it because of internal stress which expands thread when removed? Or if the bolt became longer then also crank thread should be longer or damaged as I doubt that bolt became longer but crank stays intact. I think it is really difficult to see it in the picture and what we see there is just production tolerance.

Recommendation to reuse bolt comes from former Jag mechanic who has his own Jag workshop now and plenty of experience with Jag engines and naver had an issue when reusing bolts. He recommends to replace bolts for 5.0 engines.

 

Another "heretic" solution is to shorten original screws

I am awaiting latest timing chains, tensioners, blades and guides delivery and then will finally know if the engine is OK or not.

 

Hi Zdicho,

I don't know your former Jag mechanic, but plenty of long-time Jag mechanics I have encountered in person and online are capable of incorrect assumptions and poor judgment. For example, 30 years ago, I visited a former Jaguar dealership mechanic with a good local reputation to ask what transmission fluid I should use. He said he used Dexron VI in all Jaguar automatic transmissions "because it is the newest fluid that replaces all older fluids." So I tried Dexron VI. Some weeks later, I realized the torque converter always seemed to be slipping slightly. After doing some research, I learned that Dexron VI is 25% thinner than Dexron III, the fluid that Jaguar and ZF specified for the 4HP24 transmission in my Jag. The thinner Dex VI could not provide the proper energy transfer in the torque converter. After switching to Redline D4, a high-quality Dexron III equivalent, all was well again. Some guys just "think they know better" but never bother to actually do the research to understand why the factory engineers said a repair should be done a certain way.

Regarding the torque-to-yield crankshaft bolt, as I said previously, it is possible that the old bolt in my photo is longer than the new bolt due to manufacturing tolerances. But based on what the technical literature tells us, the most likely reason the old bolt is longer is that it has been physically stretched by the 12 to 14 tons of tensile force to which it has been subjected. The bolt is designed to stretch past the point of elasticity until it literally deforms. Its metallurgical structure changes and it becomes permanently elongated. The bolt typically can only undergo this elongation one time before it is deformed past the point of being able to provide the proper clamping force when re-torqued and stretched again. Here is a simple explanation from Wikipedia:




I don't know why your Jag mechanic should think that it is more important to change the crank bolt on the 5.0L engines than on the 4.0L engines. The 5.0L bolt is a little longer, but it is the same M16 X 2.0 thread, and the crankshaft-to-damper connection is the same, with the conical split collet. In fact, the split collet is the same part number on both engines. So the very same bolt-stretching process is involved on the 4.0L and 5.0L engines.

Another thing to notice in the Jaguar documentation is that if your crank doesn't have the split collet or "locking ring," the correct torque spec is 80 Nm / 59 ft. lbs. plus an additional 80 degrees of rotation, to result in an estimated torque application of 320 - 400 Nm / 236 - 295 ft. lbs. This doesn't mean that you use your 400 Nm torque wrench to torque the bolt straight to 375 Nm. It means that you very carefully torque it to 80 Nm, then turn it an additional 80 degrees. This is usually done with a breaker bar and angle gauge. The actual final torque spec is less important than the angle of rotation of the bolt, which stretches the metal in the bolt to the optimal degree specified by the Jaguar engineers. The degree of stretch is more important than the final torque measurement, and the stretch is determined by the angle of rotation and the thread pitch. Threads are just an inclined plane or wedge wrapped around a cylinder, so the distance the bolt is stretched by any given angle of rotation is easily measured.

Again, see the TSB I attached that was uploaded to the forum by motorcarman (Bob Gauff), a former Jaguar mechanic who has proven over many decades of contributing to the forums that he really knows his stuff.

Cheers,

Don