I have a pretty bad leak from the upper timing chain tensioner, the one just behind the rotor distributor . There are two 10mm hex screws which are easily removed. I have ordered the O-ring/gasket kit. However, how do I remove AND reinstall/tension the tensioner. It does not budge and I see no additional screws on it. Thanks for your help.,

 

TSB for the part you describe.

I just tap the tensioner back and forth with a drift at the bolt hole edges to break it free if the part has been installed for a long time and is stuck.

bob

 

Thanks. Do you need to manually crank back the tensioner using the hex bolt before it will move or does that not matter? I guess I will install the updated self-tensioning tensioner such as to not have to figure out how to retention it again. Regards, Bo

 

The original type tensioner needs to be disassembled and the spring setup compressed and installed. The hex key is used to 'release' the tensioner back into working position after installation.

bob

 

Upper timing chain tensioner with first bolt removed. This is what I am looking at. The "stub" sticking out is round so I assume that I do not ratchet anything back before attempting removal? Thanks, Bo
1994 XJ6 XJ40

 

Hi Bo,

The round part is the end of the valve, which has to be removed to retract the tensioner. If I recall correctly, you can loosen that top screw, swing the top clamping plate up and carefully remove the valve with a pair of needle-nose pliers. The valve has a couple of small O-rings you'll want to replace.

Check the Haynes Manual for instructions for removing and reinstalling the upper timing chain tensioner. You can download a mostly-complete U.K. edition here:

Haynes Jaguar XJ40 Repair Manual

Cheers,

Don

 

Thank you very much. Very helpful. Regards, Bo

 

Here are my notes on how to rebuild the upper timing chain tensioner on a 1994 xj40 xj6. It takes about an hour - or the whole day if you drop some of the tensioner parts.

The tensioner is right behind the rotor distributor, top front passenger side of the engine.

0. A rebuild kit costs $15 on Ebay. It consists of 2 tiny O rings, 1 big O ring and a gasket.
1. Remove fuel pump relay and briefly run engine to depressurize the fuel system if you are going to put in the new style (I rebuilt the old style tensioner). the relay is blue and sits on top of the passenger tail light high in the fender. Remove tail light finger screws, pull back fender felt cover a bit by hand. Above black controller is a relay socket with a blue relay.
2. Take cap off of rotor distributor and use a sharpie pen to carefully mark the position of the rotor on the housing.
3. Remove the long one of the two 10mm hex bolts holding the tensioner. That is the long screw that holds the cover plate covering the little valve.
4. Now you have space to remove the 8mm hex bolt holding the rotor distributor. Lift the rotor distributor off after taking a picture of its orientating and making sure you can still see the sharpie marks. Carefully put it aside without spinning it.
5. Now for the worst part. You get some welding pliers or such and you grab the little valve protrusion and first turn it to loosen the dried up O-rings. You then pull straight out possibly using a big flathead screwdriver for leverage. After 15 minutes, it finally pops out.
6. Get a 3mm hex key and find the hole for it where the valve was and turn about a quarter turn counter-clockwise until you retract the tensioner a bit.
7. Unscrew the second hex 10mm screw holding the tensioner
8. Use a crewdriver, chisel or such to gently move the tensioner out by a bit so you can get a big flathead screwdriver between the tensioner and the engine. Gently wiggle the tensioner lose being VERY ready to catch the parts as the tensioner will come out as en erector kit.
9. There is the tensioner body. A spring. A bottom for the spring, A top for the spring, The business end tensioner piston head and also a little locking spacer. It is not profound how it goes together but DON'T let the spring eject any parts into the engine bay.....
10. Get a little pick and remove the totally dried up tiny O rings on the little valve. Oil the new ones and put them on. Do the same with the big O ring on the tensioner housing.
11. Play with the tensioner parts until you understand how to use the 3mm hex key to FULLY retract and lock the tensioner.
12. Put the paper gasket on the tensioner housing and carefully slide it back in such that the two vertical side flanges are vertical and will grab either side of the chain in there. You may have to first put the long screw a bit in there before you can get the little screw in there. You will be compressing the spring the last bit as you put the first screw in but be sure not to cross-tread. When the smaller 10mm hex bolt can be fitter tighten it 85% and remove the long bolt again.
13. Use the 3mm hex key to release the tension by turning clockwise.
14. Put the rotor distributor back in, carefully ensuring that the rotor lines up with the sharpie marks 100% and that the mark left by the 8mm hex bolt on the distributor mounting flange lines up with the hole for the screw. You will need a shop light but it is pretty easy to see with the light. Tighten that.
15. Mount the longer bolt and the flange holding the tensioner valve and tighten both bolts.
16. Now install the second, longer 10mm hex bolt holding the tensioner and tighten both bolts

(17. If you are installing the redesigned tensioner, there is a procedure to follow for having the oil pressure release the tensioner before you put the fuel relay in. Consult the factory service bulletin to verify. I did not do that procedure.)

18. Put the fuel relay back.

Tools needed 8mm and 10mm sockets and ditto wrenches. Ratcheting ones will make it a lot faster. Welding pliers or other pliers that mean business. Big flathead screwdriver. brake cleaner or degreaser.
Check valve cover screws while you are there anyway. Mine were lose.

 

Thanks for the great report, High123bid!

I would only add one more step to your very thorough instructions. Before removing the distributor, in addition to marking the position of the rotor, one should also mark the position of the distributor base on the engine, since the rotor's orientation to the distributor body is nearly as important as the rotor's position to the distributor shaft drive gear. Here are the instructions from Haynes:



Cheers,

Don