I recently acquired a 1998 XJ8 with only 28,000 miles. The previous elderly owner (now deceased) replaced all 4 timing tensioners and chains in 2006. The car was most likely sitting unused for the last 3-4 years. Upon cold start-up there is an apparent "knocking" sound that goes away after several minutes of idling or will go away immediately if I give it a little throttle (1200-1500 rpm). Note - if I give it a some throttle, there is a brief metallic sound (timing chain?) just before the knock subsides. The knocking sound is similar to a crankshaft with worn bearings. I have had the oil/filter changed (full synthetic) and the problem still occurs. After reading through several posts, It seems possible that there may be insufficient oil pressure upon start up. One posting suggested heavier oil or a different filter. Other users reported that the serpentine belt was the culprit. Yet another suggested that it may be an issue with the VVT system. Any Thoughts?

 

It sounds exactly like my 98. When cold it sounds like a bad lifter or loose valve. As you say, a bit of throttle causes a sound very much like a pump shotgun being cycled. The tapping goes away immediately. Personally I am certain it's the VVT.
I tried the an oil additive with no results. Next time I change oil I may go to 20/50. currently I run Castrol 10/40 non synthetic.
Do as I do, don't worry about it and just let it be.

 

My 1998 xj8 does the same thing. I wondered the same thing. I use full sythetic 10/30. It knock briefly untill i rev it up a little and it goes away.

 

My XJ8 (1998) does the same thing - I can rev it up a couple of times and
then ok

 

Reading all you boys are using synthetic most likely on motors that NEVER had synthetic before is IMO a BAD idea. At least that is what I have been told. I had the same thing/knocking and I did the below.

change oil asap take a full quart of Lucas oil/oil stabilizer asap with 10/30. take 64 oz of mystery oil in a full tank with super. let it idle in the driveway for 12 hours and change oil again. then place a quart in every oil change going forward of Lucas worked 4 me

 

You have been told a common wive's tale that is NOT based upon any facts... and your solution sounds a bit like black magic - which one of these mystic requirements actually got rid of your knocking? I'm going to guess the quart of Lucas per change (which, BTW, is just 80W oil with some detergent added)... everything else is likely optional and doesn't hold up to any logical explanation as to why it would change a thing.

May as well just use a high quality heavier viscosity oil to do the same job.

 

I do not run synthetic. Check this post for the sound- https://www.jaguarforums.com/forum/x...d-video-61236/
For myself, I am reasonably confident that it is a VVT issue, and while I wish it would go away, I'm not going to spend a lot of time and money on multiple oil changes, etc.

 

Although I have not had a similer issue (yet) and so have no direct experience, many here have stated that heavier viscosity oil does make VVT 'rattle' go away. I prefer heavier oil anyway - the only drawback I see from it, as far as I know, is slightly lower fuel mileage (10ths of an MPG) due to the higher drag of the oil. But, as long as it's not so viscous that volume through the galleries is reduced, higher viscosity can only provide better lubrication under harsh conditions.

 

I prefer snake oil - preferably milked from a cotton mouth at high noon.

 

I had the same cold start noises also 98xj8 w/100k. lifter noise and vvt noise (clicking) when raising idle. I also had oil light come on at idle on real warm days and in slow stop start traffic.
I used 1 qt of lucas oil stablizer for about 3-4 days maybe 100 miles. did an oil filter change, oil was really dark when drained.
I am using Castrol 20/50 now. No start up noise, lifters etc, no oil light at idle under same conditions. I am happy with results. Plan on going to 10/40 for winter use and see how that works. Good luck.

 

You have one video to listen to and I am offering another. I have two that relate to the belt tentioner. Belt Tentioner See if this matches your problem.

 

Yikes! that's one hell of a thunk from the belt. Great footage too.
Now the original poster has two videos to listen to, and two very different sounds.

 

you never know I guess, opinions are like well "aholes" right?

These wives were not very hot, and they believed it as well
one was a


service Mgr @ Jag, R&D designer @ Morosso, an 8 time Natl NHRA Champ and owner of Preceision Automotive engine builder for 35years, 1 Shop foreman at Flagship motor cars in Lynfield, SM @ Flagship since 99 and many tech's have told me that.Ron St Pierre @ Mercedes Benz warranty Rep for New England told me after MB ended up telling its dealers NOT to change the oil in crankcase for 10,000miles! LOL. He also told me that the over confidence by MB with its syntethic had cost them millions and doomed motors between 2001-2003 down the road. Kinda like how Jag doomed the 98-00 motors using porus blocks and PLASTIC guides for its chain! doh!
I used Mobil 1 in all of my car's until 05. I went to get an oil change in my wifes 02 WRX and they had used regular oil and it is was QUIETER! lol. Switched my 03 R off it as well soon after. Ran my 03 S-R til 178k and the guy is still flooring my old Jag with over 219k! LOL.

Regardless my XJR is very quiet and it worked for me. So I offered up some advice from previous experience...

 

cheaper than junking your car though IMO. Lucas qyart is 12bucks I think and a Jiffy Lube LOF is what 45 bucks? I would try it. and then video after so we can hear! would be cool to see documented change, IMO would be incredibly helpful to other Jag members.

 

Exactly.

Lucas Oil products are not exactly great products. Some of their application recommendations are completely inappropriate and will result in damage to the vehicle. Getting reimbursed for damage is a piece of cake with Lucas distributors. All it takes is a phone call, a repair receipt, and a check for the full amount is in the mail. It would seem to be that they are well aware that their products aren't that great.

As far as mainstream synthetics go in the North American markets ... it's all dino to begin with.

There are also "thin" and "thick" oils within a viscosity grade due to API testing methods. So for example, not all 5W-30 behave the same.

The anecdotal story about the Subaru WRX being quieter on conventional oil probably has more to do with grade differences than formulation differences. The poster of that story did not bother to provide details on grade, brand and formulation for either the old or new oil. That makes any comparison completely invalid. Even if they had been provided, it would still be only a single anecdotal experience.

 

I just did an oil change, heading into our admittedly mild winter. It seldom drops below freezing here. I was thinking of 20/50, but consulted the owners manual again and decided to try 5/30 instead, due to the season. Maybe in the spring I'll try 20/50.
As for junking my car, I am not aware of any VVT problems damaging the engine. Tensioners, yes.

mpleeds, is the sound in my video the same as what your car makes?

 

Although I thank you for the anecdotes, they just prove my point - that wive's tales and information NOT based upon fact (and often disproved when compared to fact) gets passed around and believed regularly - when you hear rumors of a problem (factual or not), one is much more likely to follow the rumor's advice; you're not likely to try it to see if it damages your engine, are you? Then, you pass this untested information along as if it was fact... but it's not.

Service mgr at jag? Engine builder... NHRA champ? Come on. This is EXACTLY where I expect the worst advice to come from. They pass on what has worked for them without ANY science involved or any understanding of the scientific process. This IS the problem. None mentioned have degrees in chemical engineering, nor would I expect them to understand petroleum polymer physics... anecdotal statements from them are simply single points of data to enter into the data base awaiting the filter for true information; and the MB reference is simply related to mileage between changes - how is this even relevant. It's very nice that you know the MB Warranty rep for NE.

RE your particular issue: Your Lucas (as I stated earlier as just 80 wt oil) simply increased the overall viscosity of the oil, fixing your issue - although you may have done many other things prior to the end result, including waving rabbits feet over the block, nothing EXCEPT the Lucas makes logical sense vis-a-vis your results... and yes, the a-hole reference is very appropriate for OPINIONS - of which you are trying to pass as fact - not so.

RE changing from dino to syn - Don't get me wrong - I have nothing bad to say about dino oil and sure, you can get 200,000+ miles using it... I just won't allow someone to make misleading statements about dino vs syn oils without attempting to correct the error. Bottom line, use what you want and change it regularly at reasonable intervals.

For the OP's issue, if it is the VVT noise, simply changing to a higher viscosity oil will often quiet it.