Hello, a friend of mine wants some help replacing the 4 timing chains and tensioners and guide rails and such. The vehicle is a 97 or 98 i forget which xk8. I have never messed with a car like this before. We are both sort of learning as we go. He has a factory cd i think that goes through the steps on how to do everything and he bought the tools to lock the cams and such. Our main problem if figuring out how to set the timing. We do not have internet access at the shop so i am asking for information i can print out to help with the job. I will probably start doing it sometime this week or maybe weekend. Thanks.

In case you are interested i drive a 1984 mercedes 300d and a 1978 chevy k20. Keeping it old school. lol

 

Welcome to the forum Joe!

Someone is going to come along shortly and suggest that you introduce yourself on the New Member forum.

New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum

There are any number of threads on replacing the cam chain/tensioner parts. If you are doing both the upper and lower you are going to need the timing tool kit that is available for loan/rent or purchase. Here is a link discussing repair and Gus has a kit for loan:

http://www.jagrepair.com/JaguarToolLoanDirectory.htm

. . . and here is about the best thread on replacing both the primary and secondary tensioners, chains and guides.

http://jaguar.blackonyx.net/tech/timingchain.htm

Secondary (upper) tensioners are much easier and only require a couple zip ties.

https://www.jaguarforums.com/forum/x...ics-how-52653/

 

Follow test point's links for a huge amount of information. However, as a relative newcomer to the Jaguar V8 fraternity, the thing I couldn't initially get my head around is that, unlike every other car I have owned including Audi, Volvo, Mercedes and others, there are NO marks, dots, arrows, slots, keyways etc on any of the four cam sprockets. If the crankshaft is positioned correctly using the correct tool in the torque converter, and the flat machined segments of the four camshafts are held horizontally by the two locking bar tools, then it doesn't matter what you do with the camshaft sprockets which are basically held on the camshafts by tension. There IS a keyway (woodruffe key) on the crankshaft pulley but this isn't relevant to the timing. Obviously, what follows from that is that the bolts which secure the sprockets to the camshafts MUST be tightened to the correct torque - that's all that's holding them on, and in the right place.
Hope that makes sense ?
Cheers,
David.

 

. . . if I may summarize . . . the cam sprocket to cam is constantly variable as there is no key way, splines or other alignment method other than a friction fit . . . and it is not even a taper.

One degree off is one degree off and somewhere above that one degree makes a difference. Perhaps that is why I doubled the torque on the sprocket/cam bolt.

 

ok a couple questions. What type of loctite should i use on the bolt threads? Also the timing chain on one bank broke while the car was driving so either one or both cams were taken off. How do i make sure the cams go back in the right position so i can use the cam locking tool? Thanks

 

I didn't use any locktite on my work on just the secondary tensioners. Don't remember any JTIS call for it.

Your initial post indicated that you were going to do the full Monty primary and secondary and guides. You start by locking the crank shaft into place, then the primary chains aligned to the intake cam, then align the exhaust cam to the intake cam.

At the front end of each cam is a flat area that is locked perfectly parallel with the cam lock down tool. That is the correct cam alignment. Both sides will be in alignment at the same time so turn the engine by hand until the undamaged side is aligned and locked down. Then align the exhaust cam on the other side and lock it down.

 

I have 2 procedures on my page that might help.

Link JagRepair.com - Jaguar Repair Information Resource

 

I will have to talk with the owner to find out how far he went with taking off the cams but my concern was what if the cams one one side were removed and the sprockets and chain. I just line up the cams to be locked down with the tool then the sprockets go back on a half a tooth off from each other? Also is there any way to change the base timing manually or is it kind of set permanently at one location once all the chains are back on? Thanks for all your help so far guys.

 

Joe,
Forget sprockets and chains - they are not relevant to the timing. Remove the sprockets and chains completely. If the crankshaft is in the correct position (special tool in torque converter) and the four camshafts are in the correct position (flats on camshafts held horizontally by the two special tools), then the timing on your car is now 100% perfect.
At this point you can re-install the crankshaft sprocket, the tensioners, chains, & camshaft sprockets following the instructions in the links from testpoint and Gus. You can't install the sprockets "half a tooth off" because the camshaft sprockets don't have a key-way. - that's what I meant about "not being able to get my head around the fact that, as far as the timing is concerned, the sprockets are irrelevant. You can set the timing BEFORE the sprockets go back on the engine which, in my experience of other engines, is sort-of counterintuitive. Obviously you need to follow the instructions on making sure the chains are correctly tensioned before finally tightening the sprocket bolts, but you will find all that in the links suggested.
Cheers,
David.

 

I would guess the 'half tooth' comment refers to the crank shaft sprockets which are permanently aligned a half tooth off rather than inline.

No, you cannot, or should not, 'tune' the timing. There are Variable Valve Timing (VVT) devices on the fronts of the intake cams managed by the ECM for that purpose.

 

My concern is the statement, the chain broke while the engine was running. Doesn't this create a bent valve or two.


Wayne

 

Not always. Motorcarman recently mentioned that he he repaired a few with no damage.

 

It's just the luck of the draw. When the chain breaks or jumps off, the cam stops turning of course. If it happens to stop in a position where no valve is open far enough to get whacked by a piston as it goes by, you win. Otherwise, not so good.

I wonder what the odds are?

 

I guess my friend is one of the lucky ones because he did not bend any valves. Anyway i get the timing now i was just a little confused because most vehicles i have worked on The gears had to be set a certain way or there were marks for timing. In this link http://jaguar.blackonyx.net/tech/timingchain.htm i see he used a plug in place of the crankshaft position sensor to stop the crankshaft from moving. If the chain broke wouldn't the crankshaft be off from where it is supposed to be? How do i know where the crankshaft should be set?

 

Joegreen, Read item #9 of this thread. I'm still trying too get my head around the timing chain sprockets not being keyed, I understand it, but not the way I was trained.


Wayne

 

With the plug in the ignition timing sensor hole the crank shaft is not only prevented from moving but is in the correct position to match the cam flats being locked down. All you have to do at this point is put the chains on.

 

Have a look at post #9 on this thread .....
https://www.jaguarforums.com/forum/x...-found-117609/

 

"The crank position sensor can be found in the front of the crank on the engine block below or next to the water pump in many applications. It can also be located on the main crank pully or the flywheel. The orientation of each make and model's engine is different, so the position sensor could be near your fender or near your front bumper depending on the car. They are typically made of magnets and oil and work on the principles of the Hall Effect."

Do you know where this is located on a 1997 model? So once i get the crankshaft locked down and the cams locked down them its just a matter of replacing the chains, tensioners, guides ect. Is the crankshaft locking tool the same whether it is located on the front or rear of the engine?

 

Perhaps you need to re-read the above links again for a little better comprehension.

The CPS is mounted at the bottom center of the bell housing and 'reads' off the flex plate where you are going to remove it and replace with a locking key mounted in the appropriate hole in the plate. The early engines, the AJ26's had a triangle to identify the alignment, the later AJ27 engines an elongated hole in the plate.

. . . and yes, once the crankshaft is locked at its alignment point and the cams are locked into theirs it is only a matter of installing the chains, etc. The chains just need to be tensioned to remove any slack on the driven side.

 

Joe,

Look at jimlombardi's post in the thread I linked to in my previous post. In brief ......... the crank position sensor is at the rear of the engine facing the "flexplate" - basically the flywheel / torque convertor. For timing purposes, this (the CPS) is removed and replaced by a special tool which fits in the same place but locates in a "special hole" in the flexplate to set the crank position or on earlier engines, I think there may be an arrow - not sure ? Note - this is NOT "top dead centre" (in old-fashioned terms) and MUST NOT be used to lock the crankshaft to remove the pulley. It puts the crank at a position where none of the pistons are at the top of the bore, and therefore will NOT hit any of the camshaft lobes if the cams are rotated. The four camshafts can then be rotated to get the four flat machined faces lined up. Your timing is now 100% correct. The crankshaft sprocket has a key-way to ensure that the two sprockets (one for each primary chain) are correctly positioned relative to each other (half a tooth apart) but this has no overall effect on the timing. The camshaft sprockets and chains can now be installed and you can move them about as much as you want while they are loose as they have no keyway - it's only when the bolts are tight that their position is fixed relative to the camshafts. It's essential to get the crankshaft in the correct position first, as a piston at the top of the bore can collide with an open valve. But ..... once the crankshaft is correctly set, you can play around with the camshafts without any danger of expensive damage. If you read all the posts and threads suggested, it will all become crystal clear.