Well, I have a 2001 XJ 308, it is form 4/2001 and has 55000mils (80 000km). The car should have the second series tennsioners but in any case I want to substitude them. At tthe moment I have not to much time for my cars so if I want to do the complete job with upper/under tensioners and chains it would be a work of 2 days.
For you experience (2001) it is enough to go the easy way and change only the upper tensioners and in a year the rest?

Best Pagodino

 

Many of us have only changed the secondaries. The theory is that the primaries are not subjected to as much heat, and if they do begin to fail they will rattle on startup. Also, a failed primary is less likely to cause catastrophic engine damage.

 

Look up my headgasket thread I have going to see how close this car came to a primary failure. Since your car is a 2001 I'm not sure what style primary tensioners and guides you have. With that said, since the parts can be had for about $170 I'd do them both. Not that much more work.

 

Most of us have replaced only the secondary tensioners and have gotten away with it. The higher head heat seems to be the most significant factor in primary vs secondary plastic tensioner failure. Your car has the spring assisted second generation tensioners. The spring was added to eliminate the 'rattle' notice of impending failure. It did nothing to solve the ultimate failure of the devices.

So, yes, replace the secondary tensioners and at your 55k mile level evaluate the primary replacement later. The primary chain failure does not post the same risk of total engine failure that the secondary chain issues do.

 

I agree that it would be better to at least do the secondary tensioners now rather than wait to do both. I do not recall anyone reporting a valve crash due to primary tensioner failure. There have been a number of folks report engine failures due to secondary tensioners, even in low mileage engines.

 

+2 at least, the secondaries.

I did mine 30 months ago: 25k miles later, no indication of primary failure, but the peace of mind of getting both done might be worthwhile, and provides an excellent opportunity to renew the cooling system and aux belt system since all of those parts need to be removed to get at The primaries and the chains. There are many good threads and YouTube descriptions to help you through it.

If I were going to do my secondaries again, I think I would renew with new second generation tensioners -- much more sophistcated design than the metal ones and good for fiftyk miles

 

Where do you guys get your info? These issues have been discussed at length on this forum and certain facts are listed below.

It is a TREMENDOUS amount of work to do the primaries! You have to take off the entire front of the engine!

I think you are confused. The second gen tensioners are plastic and identical to the first gen with the addition of a spring assist. The plastic still cracks and fails. 50K? They have failed in 20K!

The "gold standard" are the third gen tensioners are all metal with spring assist and were installed in all 4.0 engines from late '02 onward.

Did you replace your first gen tensioners with the same sure to fail plastic first gen? Why?

A failure in the secondary tensioners can be catastrophic, your valves will meet your pistons. The primaries usually give a lot of notice with noise before they fail and it is usually not going to destroy the engine.
Vector

 

I think the metal ones are noisier; but you are right, if you plan to keep it or drive high
mileage, go third.

 

A "Tremendous" amount of work would be head gaskets..

 

Agreed. Replacing both primaries and secondaries as well as a new timing chain wasnt that bad. Just put aside the time to do it properly, rushing will only lead to problems.

 

I call BS here. I don't think you really know what you are talking about.

Please stop giving bad advice to replace with second gen tensioners, they are no better than the first, except that they have spring assist for startup, before the oil pressure comes up to move the tensioner into position.

How can they be "noisier" when the plastic rider is the only part that touches the chain?

It has been well proven here by lots of owners real teardowns that the second generation units fail just like the first because the body of the tensioner is made of plastic and it cracks and fails. The third gen are all metal, except for the rider that touches the chain.

Why would you replace the failure prone first gen with the equally failure prone second gen when there is no cost or time difference? So that it is "quieter?" Bad advice not based in facts, please stop spouting this nonsense.

I will tell you what is quiet: A Jag with an engine whose valves have met the pistons on a blind date with plastic tensioners.

Vector

 

I compared the design of the plastic tensioners to the metal ones yesterday as I was replacing them. First of all the metal primaries have a racheting mechanism. So they are always optimally tensioned. They are simply superior, improved design. I don't see how they could be noisier.

 

For those whose reading skills are as impaired as Vectors: I RECOMMEND YOU REPLACE YOUR FIRST OR SECOND GENERATION TENSIONERS WITH METAL THIRD GENERATION TENSIONERS. As I did.

However, It seemed to me that my engine was quieter on start up with the OEM plastic tensioners (albeit, with a 3/8 and 5/8 rip in the old ones). Just my opinion of what I was hearing..

Adam: appreciate your examination; which I did not do. You are clearly correct.

Vector Lad: work on your anger management: the issue is not worth a 11 line diatribe, especially from a Regional Coordinator.

 

Thanks for the advice. Something else you wrote I don't agree with.

You have made two assumptions: That I am illiterate and angry, neither of which are true. I was merely trying to keep someone from taking some bad advice by installing inferior 2nd gen parts.

You may be embarrassed by the advice you gave, but don't try to make it my my fault for calling you out on it.

Yes, I am a RC, and will keep my exchange with you civil, I suggest you do the same and not insult me again.
Vector

 

I recommend doing the whole thing. If one set it gone, the other is definitely just as bad. Tension on the chain (applied by all 4 tensioners) was all that was holding some of mine together. As soon as tension on the chain was gone most of mind started shedding pieces and parts.