I have a 2001 xj8 with 133k miles on it. From what Iv read it seems I may need to replace the tensioner.
Symptoms
1) loss of power
2) hard start in the morning
3) I had a restricted performance message pop up, though I cleaned the maf sensor and the check engine clearded later on in the day.

So my question. Is there a way to tell if the tensioner was already replaced by the previouse owner without tearing it apart too much. Or is there something else i can check before taking on this seemingly daunting task?

 

I don't know of a way to check without removing the valve covers (cam covers), sorry. I tried to snake an inspection camera in through the oil filler cap on my 2001 XJ8, but just couldn't get it to work. The upside is that removing the valve cover really isn't very difficult.

I would definitely see what codes you are getting when the restricted performance occurs. Do you have a scanner of some sort? The symptoms you list could point to so many different things.

Many people only replace the secondary (upper) tensioners, which is far less "daunting" than replacing all of the timing gear. When I bought my 01 XJ8 I replaced the secondary tensioners immediately, and then a few months later replaced all of the timing gear.

Let me add to that: I wouldn't even worry about starting the engine and checking codes UNTIL you confirm that your upper tensioners are ok. If they are in fact failing then any start of the engine could potentially be the last.

 

Thanks for your reply. I will check the tensioners and see if they are plastic. Probably won't be until tomorrow. The codes I got were
P0174 bank 2 comb too lean
P0171 bank 1 comb too lean

 

And how long does it take to replace tensioners?

 

Reduced power and lean codes; could be as simple as a bad vacuum leak. Could also be a bad MAF, fuel pump or fuel injector problem..etc. Hard starting could also point to a failing fuel pump I guess (or a bad coolant temperature sensor).

I'm all over the place, sorry. haha. I work on my cars as a hobby so I have no mechanic training, but the above is where I would start if I was researching the problem.

I did my upper tensioners in about 3 hours, but the whole experience was brand new for me. I could cut that down to at least 2 hours if I had it to do again.

 

Awesome I will start there and see what I come up with. Any special tools to buy for replacing the tensioner?

 

Search/research "upper tensioner replacement" on here and there will be numerous threads which include instructions and pictures. I don't recall any special tools. I used the much debated "zip-tie" method when I did my upper tensioners only. The car ran great for the 3 to 4 thousand miles until I got around to changing all of the timing gear.

I have the proper locking tools now so I would not have to use the zip-tie method if I were to do it again. But, it was easy and it worked.

The following is a very long thread on the topic. One of many....

https://www.jaguarforums.com/forum/x...ners-how-4747/