I have heard that engine numbers 0108130000 (midnight 13 August 2001) and later have metal chain tensioner instead of the plastic ones that tend to crack and fail. Is this true? I own a 2002 XKR with 71,000 mi on it. Also where on the engine block would these numbers be? Thanks for any information about this! KWinn

 

The engine number is on the front of the engine by the thermostat housing - 10 digit number. You piston code ( 8 digit ) will also be in this area. Bearing codes are stamped on the side of the block down by the engine mounts

To my knowledge - the metal chain tensioners weren't fitted till the 4.2 V8 came out in the 03 and up models. All the 4.0L will have had the plastic ones fitted.

If you're not the original owner of your XK, its quite possible they may have been changed. However what you need to be careful of is a lot of people only changed the secondary chain tensioners, the plastic primary ones may still be fitted. Only way to check is to remove the cam covers to check secondary, and you should be able to look down the front timing cover to see if the primaries have been changed.

 

left of the block drain plug behind left motor mount

or pull the valve covers and check

 

The EARLY engines have the number/date by the thermostat housing. The later engines have it on the left side of the block.

 

Hi KWinn,

There is really only one way to determine what is TRUE for your engine, take a look with your own eyes. Your car may have a report of a tensioner replacement/upgrade, which may be factual, may be factional but incomplete (secondary tensioners only), or not factual. Trust your own observations, to do otherwise could be a painful experience.

All the best,
J. Lippmann

 

As pointed out , Visual inspection is the only way to know what is in the engine now.

I have a late 2002 XKR. It had the usual tensioner failure at about 115,000 miles under the previous owner. I’ve owned the car for 3 + years , since 116,000 miles, and now it has about 166,000 on it, more or less very trouble free.


if I were in your shoes I would not be driving the car at all until the tensioner issue was resolved.


Z

 

So what's the buzz on the tensioners? I assume that the engine is an 'interference engine' (almost all modern engines are). Are there any tell-tale signs of impending tensioner failure? Or do they just go boom while you're not looking?

Thanks.

 

BOOM. !!!

as far as I know, it’s primarily a 4.0 engine issue.


Z

 

I found this on some website. Supposedly from a self-proclaimed expert.

"The timing chain tensioners in this model V-8 were plastic and with a combination of heat and friction can fail. The first sign of failure is a rattling noise on engine start-up. Over time the rattle will be heard at idle cold or hot. In the most extreme case the tensioner will completely fail causing the timing chain to jump, which can cause pistons and valves to collide."

Is there a tell-tale rattle before they go boom? Or is the above simply wishful thinking?

 

the secondaries break a pad and let the chain flop around or jam the chain and break it. the cracking around the piston is not the actual cause of failure.

primary tensioners rarely fail, if they do it causes a momentary startup rattle. all the guides are cracked along the middle, non-issue unless chunks fall into your oil pickup. sometimes they break at the bolt hole, you will hear noise.

primaries are not worth fixing unless you have an issue.

 

The first gen plastic might give a rattle, the second gen plastic don't apparently.

Engine # as above, or documentary evidence of replacement, is good:- any doubt and the cam covers should be lifted to check.

 

Here is my similar thread from about 10 years ago. I hope that you are as fortunate as I am. I have the updated (Morse, Ramsey, etc) stronger silent chain and metal tensioners. My build date is January 2002. I definitely agree with looking under the cam covers.
https://www.jaguarforums.com/forum/x...nsioner-55895/

 

The upper tensioners? The chain didn't skip any teeth? The engine wasn't damaged? Sounds like you got lucky!!!

 

sorry that was a response to Zray's 3/29 post