I have 98 XK8 with a rattle from the passenger side at start up with a little bit of acceleration.... so we pulled cam cover and found we had new primary and secondary tensioners... we have 26mm of slop between the top of the tensioner and chain... the lower part of the tensioner seems tight...

Is this do the VVT ( variale valve timing ) ?

 

A little more information. If I put an allen key (hex key) in end of valve cam and rock it back and forth I can increase the slop in the chain and actually see the lower side of the tensioner colapsing without much force required. Do the tentioners have a built in check valve system to keep them from collapsing? I can see aqt least a 1/4 of an inch expansion and copllapsing of the bottom side of the tensioner?

Is this normal?

 

A few observations... as you can see in the pictures we advance or retard the exhaust cam with a hex key.. you can see that I can put a pinky finger under the change, and for a reference point you can see on the tape measure the gap between the tensioner

 

Only one side of the tensioner puts tension on the chain, so that is OK.

The other side should provide considerable resistance to collapsing, so that is concerning.

I am suspicious that the new tensioners were installed without replacing the bolts. The new bolts are slightly shorter. If the old bolts were used, you will get an inadequate seal between the tensioner and the head.

In a pinch, you can grind a couple of mm off of the end of the old bolts and reuse them if this is the problem. You will not be able to tell if this fixes the problem until you replace the valve covers and run the engine to repressurize the tensioners.

 

I went down to Toms to help him change the tensioners (My hand in the pictures) and noticed there is very little tension required to collapse the tensioner and thought it was very odd. If I had to guess I would say that the Exhaust cam is easily movable between 5-8 maybe even 10 degrees with the hex key in the exhaust cam by rotating the exhaust cam. Seems very excessive to me.

IS there any type of check valve in the tensioners to maintain pressure once the tensioners have been filled with oil ?

Barry

 

Yes there is...it should be very resistant to collapse once pressurized.

 

WhiteXKR- If the bolts are too long shouldn't be able to slip a feeler gauge into the joint with the head?

 

From memory i think the top tensioners are handed. if you have them fitted on the wrong side, the oil ways won't be lined up, so they won't pressure up.

 

The pic shows that the correct Tensioner is mounted on the Right Side. The Fixed Shoe faces Up and the Movable Shoe faces Down. Opposite for Left Side.

 

There is very little pressure required to collapse the tensioner in Windy City's XK8 which leads me to believe that if there is a check valve in his installed tensioners it has gone bad or has something blocking it's ability to retain pressure in the tentioner. IT moves just as easy as one that is brand new and never been pressurized.

I did notice that it had a Fram oil filter. would a fram filter have a check valve in it to maintain tensioner pressure? and if it did not would that make any difference with the tensioner retaining pressure? I cant see how that would be but stranger things have proved me wrong.

Thanks to all who have chimed in so fast. I'll discuss it with Tom and see if he wants to change the tensioners and chains tomorrow based on the new information provided today.

Barry

 

Make sure you have the shorter tensioner bolts or you will continue to have the problem even if you change the tensioner.

 

Maybe a good idea to pull one of the bots before doing anything else and compare it to the new bolts that came with new tensioners? If it's longer than the new ones replace one at a time and button it up and see what the sound is like?

Barry

 

If you are ordering parts from a Jag or Ford dealer, the bolts do not come with the tensioners...they must be ordered separately.

 

I got a complete kit from Christophers on E bay including bolts, gaskets, and open chains with master links

 

I agree it is definitely worth comparing the bolts before doing anything else.