Hi Friends, I just got a 1998 XJ8, a beautiful luxury car and I have to say I got it cheap because of a tapping noise on the valve covers. I read here all about the tensioners being the culprit on this year model, so I've removed the valve covers to check them out, I found previous owner already have done that service and both tensioners are metal 3rd gen type, now here's the question, I found some issues I'm not sure if they're normal, 1st with the engine off, the secondary chains have (to me) a lot of slack, I can rise the chain with my fingers about 1/2 inch, both tensioners are on the full retracted position (as they come new) and I can move the piston with my fingers up and down, also I have tried to crank the engine with the covers off hoping to see the tensioners go up as soon as it build oil pressure, but instead I see a pressurized oil spurt coming from a hole on the top of the tensioner (I understand there is a check valve there?), my question is: does this behavior is Ok or the tensioners have to be replaced?. have someone had 3rd gen metal type failed?. I have tried the local Jag dealer Mechanics, did the same question but they just looked at me as if I was speaking swahili, seems they either don't want to share info or don't know what I'm talking about. I hope someone here can give me some advice or share your experiences. Thank you.

 

This isn't right. The tensioners are supposed to ratchet out and not go back.

 

The lower tensioners lock out, uppers don't, not sure of oil spurts and slack chains.....sounds like you need to replace them.

 

Thank you Boomer, I was thinking the same, but the dealer confused me telling me this secondary tensioners are moved only by oil pressure and they go down as soon as the engine stop running, but I believe they should hold a minimum amount of pressure to keep the chain tight the first seconds after start the car, and the leaking through the upper hole when the car is running doesn't seem to be right, how is suppose to build pressure if the oil is going out through that hole?, I forgot to mention the car is only 106K miles, no check engine , no lights, oil pressure is 60 PSI at idle I think is right?, and other than the knocking engine has plenty of power. the knocking goes away as soon as I rev it up, when I let it idle for a while start again.

 

I haven't changed mine out yet, but only know what I have read here. I would think that a slack chain at startup would be risky.

 

You are one crank away from damaging the engine. Some have had oil pressure issues due to using the longer original bolts that bottomed out before sealing the tensioner. But you describe oil from the top of the tensioner.

I would get it replaced without cranking the engine again.

 

Perhaps they were improperly installed. And that is the reason it was sold.

The tensioners arrive in the packaging with a retainer pin that must be released for proper operation. Look for something that looks like a big bulletin board push pin with a bright orange top. They would be perpendicular to the long axis of the tensioner near the plunger end. Be aware that the plunger is on top on one side, and on the bottom on the other.

If they are still in place, that is the problem.

You can find out what they look like by referring to a photo on ebay or on this forum. ebay would be easier.

edit: Also pay attention to what testpoint said about the longer bolts. That can prevent the tensioners from achieving a proper oil seal at the tensioner to head interface. That can cause "... the knocking goes away as soon as I rev it up, when I let it idle for a while start again. ..."

Overall, it sounds like a botched install by someone who did not know the finer points of the job. That means you should consider redoing the job just to ensure that the cam timing is correct, or at least check the cam timing. This applies even if you reuse the same tensioners.

 

Thank you all for the prompt response, I just ordered new set of tensioners, original ones and a set of new bolts, They'll arrive in a couple of days, I will replace and will let you guys know if I could solve it. Thank you very much!!

 

You could also have a stretched secondary chain. I replaced one under my post Tensioner, my turn

 

YEAH THAT BS. Once theyre tensioned they should stay that way. waiting for oil pressure to go to the top of any engine is NOT instantanious. That can lead to chain whip snapping a chain or tensioners. Always be carefull who you talk to. We dont know everything and talking to an advisor at a dealer or anywhere many times leads to incorrect info. And then there are those that will purposely lead you down a dark road because youre not spending money there. I many times will NOT help people on the phone because most often theyre shops that are trying to figure out how to do a job properly taking money from me. and at times Ill have to FIX others screw up made way worse than they should have been.
Just like a upper tensioner job from a "European" shop here that tensioned the slack on the wrong side throwing the timing off when started. They threw coils, plugs, and wanted to put an ECU in till the owner finally pulled the car and brought back to me. He apologized since Ive worked on the car for yrs. He was just trying to save some money.....$400 later I had all their work fixed properly.
I fixed a couple others issues for free and gave him the website to send his rear view mirror off to be fixed instead of a new expensive replacement too.
I would think older too long of bolts oyoure job to as the issue as first thought

 

Wzarach


I have 1998 XK8 with similar issue. I had a local garage installed secondary tensioners. It will knock/click for about a minute or two on cold start up, then you here a clank, as if something was engaging and then there is no more noise. Warm start up no issue, just when cold , sitting overnight. Car runs fine otherwise. JTIS indicates oil is suppose to come out of secondary tensioner to disperse oil to chains so I don't think that is an issue. Regardless was there a final resolution Diagnosis?