ive noticed for about 2 months now that I've been getting a knocking noise from the engine on startup thats been getting progressively louder. It becomes very very faint after 2-3 minutes and eventually subsides. This happens when the engine is cold. I've checked the oil level and its full. 10w-30 mobil 1. Car has about 154K on it.

 

Timing chain tensioner ( oil hydraulic pressure extending ) or oil pump lever arm binding stuck as you mention that it goes away after the oil warms up ? Have you used any oil treatment to unbind these devices . I recommend Rislone shortly before oil change .

 

Run heavier oil. That will help. If you don't go below 0F I'd run 20w 50. This isn't a modern engine and you aren't chasing mileage so don't use thin oil.

Link to pdf in this post.


https://www.jaguarforums.com/forum/x...54/#post283279

 

Referencing the posts above, this is almost certainly your upper chain tensioner losing its charge as the oil drains back as the car sits. This is a common issue.

Do a quick search for timing chain tensioner. There is an updated tensioner available, which is very easy to install and inexpensive.

The new tensioner alone may not solve your issue however, and as mentioned above, the other component is to run thicker oil and the factory oil filter.

Or you may already have the updated tensioner, which is indicated by an embossed arrow on the housing (see photos in tensioner threads), so check before purchasing. A lot of owners have fitted the updated tensioner over the years.

And you may find that just increasing your oil viscosity and using the factory filter alone may be enough by themselves.

Fortunately this is a relatively minor issue to resolve.


.

 

Al has a point about the factory filter not reducing the oil pressure as one manufacture I can't remember ( Fram ? ) would negate the use of the inner metal structure causing a internal paper collapse and resulting lower oil pressure .

Removing the tarnish from the piston slides in the tensioner will help it expand easier with some oil treatment wouldn't hurt

See Jaguar TSB below :

http://www.jagrepair.com/images/TSB/...er%20Start.pdf

 

I know for a fact that the chain tensioner hasn't been changed so I will definitely have to check for wear on that. I used to use my "go to" additive which was Lucas,but I neglected on the last one. Definitely have to keep using that from now on. I've been using mobil One oil filters, is the factory oil filter a Mann or a Mobil one Filter? switching back to 20w-50 too. thanks guys for the help!

 

Much has been written about the upper chain tensioner on these cars, and enormous efforts expended attempting to solve the rattle on cold start issue.
As my car periodically suffers from it, I have paid close attention over the years, and spent a small fortune replacing chains, tensioners etc to no avail.

The early AJ16 engines had a different tensioner fitted, and following problems with customer cars, a revised design was introduced, and dealers would fit the new design to problem cars. The new design does not provide a guaranteed solution, and it is not unusual to fit a brand new tensioner of the new design with no reduction in cold startup rattle. The problem tends to only manifest itself on startup from cold, suggesting that the residual oil pressure behind the tensioning piston gradually escapes over several hours. In turn, this explains why thicker oil seems to remedy the problem, as it is inherently less prone to leaking back out of the tensioner when the engine isnt running.

So if eradicating the brief tensioner noise which occurs once a day is your priority, 20/50 oil is your friend, and the general consensus would seem to be that it stops the rattle.
If on the other hand, you are keen to ensure that your engine is properly lubricated, it might be better to stick to the manufacturer recommended grades of oil.......
In common with practically all modern cars, these engines were designed to run on oil which is considerably thinner than 20/50, and unless you live in a relatively extreme climate 20/50 is far too thick. Try pouring some out of the can alongside 5/30, and you can see the difference with the naked eye.
The tensioner rattle is annoying for sure, but the "cure" is likely worse over the long term. That said, given the longevity of these engines, we may be debating the difference between a life expectancy of 500 versus 550K miles, so maybe none of our biggest worries!

 

I honestly don't mean to be argumentative, but the factory approved oil for 0 to 40+ Celsius (32-100+ F) includes 20w50 with no warnings or caveats.

There are some warnings and caveats with 0w30 and 5w30 however.

See the following Jaguar TSB for recommended oil viscosity and associated temperature range applications. A similar table exists in the vehicle car manual.


https://www.jaguarforums.com/forum/a...aj16-12-58.pdf


Startup wear may possibly be a slight consideration with thicker oil, but so far Jaguar never cautioned against its use as long as within their guidelines.

If one is really concerned with both the tensioner rattle and cold startup issues, one could fit an oil pre-charger pretty easily to the take off points for the XJR(Euro)/XJ12 oil cooler ("U" under the oil filter) or perhaps oil pressure sender port. I've heard of them being fitted to X300s before, but not seen it personally.


.

 

I have to say I completely agree with "countyjag" on this issue & in fact had a post prepared prior.
As the technical bulletin 12/61 points out, the actual noise heard is temporary chain rattle until the tensioner is recharged (ie oil & pressure restored)
I also note that the bulletin makes no reference to a change in oil viscosity, it is purely a mechanical issue & is addressed as such.
In order to recharge the tensioner at a cold start we require a flow of oil to it ASAP.
A higher viscosity oil will no doubt provide pressure (resistance to flow) but will it arrive as quick as the low viscosity oil - NO.
Remember here also that we are only concerned with the first W number not the second. (ie 5W/50 vs 20W/50)
The viscosity will determine how quickly the oil can pass out of the sump ( another subject "cold pumpability & viscosity") through the filter & be pumped to all engine components. Low viscosity oil flows very quickly.
We also need to ensure we have a filter with an "anti drain back valve" so that our filter is full at start up & does not have to await oil to arrive from the sump. Majority of reputable brands filters have such valve.
Yes, 20W/50 is on the oil chart as well as 5W/40 & 5W/50 with no caveats or warnings also. I note 5W/50 basically covers the complete temp range, -30c to +40c. The only caveat is regarding 0W/30 & 5W/30 oil & relates to the second number (30) & relates to high temperature conditions.
Why after running an engine on say 5W/40 oil successfully for many miles & years would one change to 20W/50 merely to attempt to mask a mechanical issue which should be addressed (ie replace tensioner)
They are foregoing the benefit of better cold start (majority of wear takes place) protection for their engine into the future.

John Herbert
(1996 XJR)

 

I wonder if a check valve in the oil system that gives way at say 20 PSI on a 40 PSI pump system would be a solution to retaining the extended position . This would be determined by the oil flow paths and if lucky a check valve would be at the filter housing or the pump outlet . There would be flow considerations to not restrict the flow during starting warmup to a thiner viscosity .

Just spit balling .I was accused of reengineering things at work but then they needed to be .

 

Al,
I dont think you are being at all argumentitive, and anyway, if we cant argue about things like which engine oil or tyres are best, what is the world coming to?!
Having read your post, I revisited the vehicle care booklet which came with the car when it was new. The chart showing the various recommendations has temperature along the bottom axis, and my interpretation of it is that 20/50 would be the recommendation for ambient temperatures in the 25 C and upwards range. There are other recommendations on the line on which 20/50 appears, corresponding with lower ambient temperatures, and featuring lower first viscosity numbers. That said, I can see why you could interpret the diagram differently, although if your interpretation is correct, surely the 20/50 and other grades on the line would have lines of their own, like, say, 5w/40?

On the tensioner front, I cant help but wondering whether the solution might be a longer and stiffer spring behind the piston to provide slightly more initial tension.

 

My post should say 0c not 0f.

Interesting discussion.

Still would use the thicker end of the spectrum in a higher mile motor. I operate from 0f to 105f or so and used the pdf to choose the heaviest oil I could install for our winter and an OEM filter (the PO did not have an OE filter)

Mine had a similar start up rattle then a slight knock. Thicker oil remarkably reduced both so as to be a non issue.

I have no idea what the PO had in there or how old it was but it was thin and watery so I am guessing 10w-30. Could have also been old. But the PO had probably $750000 worth of cars so I don't think maintenance was ever an issue.

I went from "better plan on a tensioner" to "no worries" with an oil change.

 

Mann has been a Jaguar filter OEM for decades, along with Mahle, and more recently, Valeo, Filtrauto and Hengst. Mann oil filters include both bypass and anti-drain back valves.

Mobil 1 filters are made by Champion Laboratories, Inc., which, to my knowledge, is not a Jaguar OEM. However, Mobil 1 filters are generally considered to be of excellent quality.

Mobil 1 Oil Filters by Champion Laboratories

Cheers,

Don