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This job is on my to do list.... No noise from the chain at this point, but I would just like to satisfy myself that all is in order regarding tensioning
Just got my 19 XJR back from the R493 recall, and one of the items their "old car" long time mechanic noted in the overall inspection was the tensioner rattle on cold start. He said it wasn't a major concern, although it does tend to wear the upper tensioner material over time where the 1988-1994 (I think I have the years he said correct) version never did even though they had the same parts. He said he and his old-timer peers believe it is because of lighter weight oil being used in later models because the only thing that changed with the oiling and tensioners in that timeframe on the straight 6 was the deletion of the oil-cooler and specifying lighter oil to improve and meet MPG requirements.
He said he and other Jag mechanics recommend two things if the rattle continues after fitting the 'improved' tensioner (which I have):
1) 20W-50 oil
2) Jag branded oil filters, which at least he knows have the proper drain back valve
He said even if I do my own oil changes, just get a few of the Jag branded filters to keep on the shelf.
This of course is the same advice we've seen posted here before, but it's good to see/hear that from a long time Jag mechanic as well as another point of confidence.
My rattle is not consistent and is very brief, but does show up a couple/few times a week. Perhaps it depends on how recently the car has been driven and ambient temperature and how that affect drain down? Who knows.
I'll try the Jag filter and had already planned to switch to Rotella T6 (5w-40) as I am using 10w-30 now, but may consider the 20W-50 he recommended.
Just got my 19 XJR back from the R493 recall, and one of the items their "old car" long time mechanic noted in the overall inspection was the tensioner rattle on cold start. He said it wasn't a major concern, although it does tend to wear the upper tensioner material over time where the 1988-1994 (I think I have the years he said correct) version never did even though they had the same parts. He said he and his old-timer peers believe it is because of lighter weight oil being used in later models because the only thing that changed with the oiling and tensioners in that timeframe on the straight 6 was the deletion of the oil-cooler and specifying lighter oil to improve and meet MPG requirements.
He said he and other Jag mechanics recommend two things if the rattle continues after fitting the 'improved' tensioner (which I have):
1) 20W-50 oil
2) Jag branded oil filters, which at least he knows have the proper drain back valve
He said even if I do my own oil changes, just get a few of the Jag branded filters to keep on the shelf.
This of course is the same advice we've seen posted here before, but it's good to see/hear that from a long time Jag mechanic as well as another point of confidence.
My rattle is not consistent and is very brief, but does show up a couple/few times a week. Perhaps it depends on how recently the car has been driven and ambient temperature and how that affect drain down? Who knows.
I'll try the Jag filter and had already planned to switch to Rotella T6 (5w-40) as I am using 10w-30 now, but may consider the 20W-50 he recommended.
.
Well.. I'm in the same boat as you, I fitted the upgraded upper tensioner about 4000 kms ago and when it was first fitted, rattle was completely gone. but now after 4000... its starting to come back so i guess there is no sense in replacing it again right? currently i'm running 5w30 so i think i should go with 10w40 next time to see if it helps. Is there like another way to eliminate the rattle?
Last edited by FrozenApple; 05-18-2015 at 07:37 PM.
I am in the same boat too, and have recently purchased a new replacement rubber O ring to fit, in case the residual oil pressure is escaping past this overnight. Feels like a long shot, as there is no visible evidence of oil leaking past the seal and out of the head. The thing which I am currently wondering about is whether a longer and/or stronger spring behind the tensioner plunger might help. In the absence of oil pressure, it is the spring which is holding the tensioner in contact with the timing chain for those first few seconds after startup. Would a bit more pressure on the chain be sufficient to suppress the rattle? Would there be any unwelcome side effects? I guess there might only be one way to find out, but I would welcome any thoughts those more knowledgeable than me might have.
I am in the same boat too, and have recently purchased a new replacement rubber O ring to fit, in case the residual oil pressure is escaping past this overnight. Feels like a long shot, as there is no visible evidence of oil leaking past the seal and out of the head. The thing which I am currently wondering about is whether a longer and/or stronger spring behind the tensioner plunger might help. In the absence of oil pressure, it is the spring which is holding the tensioner in contact with the timing chain for those first few seconds after startup. Would a bit more pressure on the chain be sufficient to suppress the rattle? Would there be any unwelcome side effects? I guess there might only be one way to find out, but I would welcome any thoughts those more knowledgeable than me might have.
It makes me wonder if I fitted my tensioner correctly, all i did was take the old one out and put new one in and assuming that it should "fire" when i crank the engine ? is that correct? or did i miss something and ... the tensioner did not fire correctly?
If it did not fire, the noise would be beyond belief.
I did fit 1 X 3mm thick washer under the spring seat, way back when I was fiddling with this, and before I stripped the front for new blades etc, and that made a HUGE difference. More spring tention when at rest.
I agonised over the "did it fire" question after I fitted mine, but as Grant says, if it didn't fire, the noise would be hellish. I removed mine just to be sure, and the spring was fully extended, so it had fired.
The issue only arises momentarily on startup after the car has been sitting overnight, so it seems to me the only logical explanation must be that the oil pressure behind the piston seeps away, leaving the spring to provide all of the tension until the oil pressure is restored when the engine starts again.
I have read of people using 20/50 oil to solve the problem, and can imagine that it might well fix the startup rattle,as the thicker oil would be more reluctant to seep away from the tensioner overnight, but I would be worried that the oil was too thick to get everywhere else it needs to get to in the engine to lubricate it properly. Grants washer behind the spring seems a much better idea, and I am minded to give it a try when I am next poking about under the bonnet. Thanks for the idea !
Can you just remove the new tensioner after it's been installed but removing its two mounting bolts and pulling it out? For some reason I was under the impression (thought I had read it somewhere, perhaps in the TSB) that once installed and "fired" one couldn't just pull the new tensioner out as the spring/plunger could come apart and fall down into the timing chain chest as the plunger wasn't held in except for its pressure against the chain tensioner blade??
BTW, my updated tensioner has been flawless since I've been watching my oil level "like a hawk"..... knock on wood.
The mechanic at the Cary, NC Jaguar dealership who services all their "old" cars (yep, that's us now, almost 'classics') specifically recommended I switch to 20W50 oil in general and specifically to address the tensioner issue. He said the 10W30 is too thin and drains down. And the owners manual does indicate 20W50 is a suitable viscosity unless in cold climates, so I think one would be OK to run it.
However, again, I still have 10W30 synthetic in mine and now that the oil has remained topped up my tensioner has behaved.
I may switch to 10W40 next time though as some additional insurance and see how that goes.
I agonised over the "did it fire" question after I fitted mine, but as Grant says, if it didn't fire, the noise would be hellish. I removed mine just to be sure, and the spring was fully extended, so it had fired.
The issue only arises momentarily on startup after the car has been sitting overnight, so it seems to me the only logical explanation must be that the oil pressure behind the piston seeps away, leaving the spring to provide all of the tension until the oil pressure is restored when the engine starts again.
I have read of people using 20/50 oil to solve the problem, and can imagine that it might well fix the startup rattle,as the thicker oil would be more reluctant to seep away from the tensioner overnight, but I would be worried that the oil was too thick to get everywhere else it needs to get to in the engine to lubricate it properly. Grants washer behind the spring seems a much better idea, and I am minded to give it a try when I am next poking about under the bonnet. Thanks for the idea !
I never did follow that "thicker oil staying put" discussion. In fact I ignored it.
Oil WILL seep out of anywhere it so desires, unless there is a DAMN good seal stopping it. Its just how it is.
When I was messing with mine, and after much Nectar of the Gods consumed, I went back a model, the AJ6, and they dont have this isssue, or it is very rare, WHY??????.
Spoke to my Parts supplier, and he agreed that MOST of the New style units he sells are for the AJ16.
Now info on the 2 engines internal specifications is hard to find, but I eventually established that the "Cam Lobe Profile" on the AJ16 is "steeper" on the "Up Ramp". Which as an Engine Reconditioner from the very old school, I understood perfectly.
Basically the cam lobe is sharper in its profile to open the valves, which gives quicker opening to said valve/s, and more power, fuel efficiency, emissions are cleaner, blah, balh, blah.
The downside is that it puts more strain on the components doing that work. As in teh camshaft is harder to rotate, so the chain is strained a tad more, and the "slack side" of the chain (where this tentioner is located) gets strained more also, and this causes a momentary "slack chain clack" as it rotates, and the instant the oil pressure hits the unit, SILENCE.
Mine had oil pressure AT the tentioner within 2 secs of the starter beginning its task, and that pressure was/is 80psi.
Without my washer addition, a slight "clack". With the washer, never heard it yet.
Mine runs 15W40 oil all year round, and the new owner does the same, coz I still maintain that car for him.
Can you just remove the new tensioner after it's been installed but removing its two mounting bolts and pulling it out? For some reason I was under the impression (thought I had read it somewhere, perhaps in the TSB) that once installed and "fired" one couldn't just pull the new tensioner out as the spring/plunger could come apart and fall down into the timing chain chest as the plunger wasn't held in except for its pressure against the chain tensioner blade??
BTW, my updated tensioner has been flawless since I've been watching my oil level "like a hawk"..... knock on wood.
The mechanic at the Cary, NC Jaguar dealership who services all their "old" cars (yep, that's us now, almost 'classics') specifically recommended I switch to 20W50 oil in general and specifically to address the tensioner issue. He said the 10W30 is too thin and drains down. And the owners manual does indicate 20W50 is a suitable viscosity unless in cold climates, so I think one would be OK to run it.
However, again, I still have 10W30 synthetic in mine and now that the oil has remained topped up my tensioner has behaved.
I may switch to 10W40 next time though as some additional insurance and see how that goes.
.
Al,
That tensioner will slide out once the 2 bolts are undone. The cam angle sensor needs removing beforehand.
The notation about things falling into the depths is more related to the old style units.
In fairness, this units piston assembly could fall out if the operator is not careful, BUT, we are all carefull, are we not??
Getting the gasket and o/ring to release its hold on things can be tough, and that could cause unitentional "wobbling" of the unit which could be drastic.
I still remove than camcover and lever it out with a large blade screwdriver on the chain contact balde.
If I have only recently fitted it, and need it out for some reason, then the camcover stays on, as the gasket etc has not yet "grabbed" the mating surfaces.
My XJR has Castrol 5W-30 Edge synthetic oil.
Chain tensioner was noisy at most start-ups, rattling for 2 secs or so.
It now has a new tensioner, and rattled once a few days after getting it back from mechanic 3 weeks ago, but not since.
Thicker oil still drains out. Thinner oil will pump around more quickly so may reduce rattle? just my theory, no proof.
Most significant factor affecting time to reach oil pressure at start-up that I have found (getting off the point) is quality of oil filter.
2 years ago my mechanic put a Fram filter instead of genuine Jaguar filter on my 3.2, to save me money (!). It would often take 3-4 secs for pressure gauge to come up, during which time I heard the dreaded big-end/main bearing rumble I remember from our old family Triumph 2500 many year ago.
When I got a gen Jag filter back on there, problem solved immediately.
Agree on the oil filter comment. I have no empiracle evidence that the Jaguar spec filter is physically different than a generic aftermarket in quality or flow, but the same Jaguar mechanic that recommended the 20W50 also highly recommended using the genuine Jaguar oil filter. Based on his years of experience it makes a difference in flow and/or drain back.
The Jaguar filter isn't that much more expensive and dealers normally keep them in stock, so one can always buy 1+ to keep on the shelf. And of course they are available in quantities online, etc.
Back to this issue for me...Around 80,000km ago I replaced all the timing chain rubbing blocks in my car (see earlier posts and thanks to Grant for his guidance). This, combined with a new upper tensioner fitted some 30,000km prior got rid of all my hot start rattles and a rather noisy chain sound on idle etc although I still had a faint buzz sound at 1500-2000rpm
The hot start issue flared again so around 50,000km ago I replaced the upper tensioner again. It improved the situation but didn't completely remove all the timing chain sounds.
So now here I am today and I'm getting the chain rattle quite badly on hot starts and a very noticeable buzz at 1500-2000rpm.
I suppose yet another new upper tensioner is needed but I suspect it will only improve the symptoms rather than eliminate them. I also suspect what really needs to be done is complete replacement of timing chains as perhaps the old ones have stretched slightly making it harder for the tensioner to do its job. Car has done 290,000km. However I am not entertaining that job right now.
Grant, or anyone else with knowledge of this issue, I recall you mentioned somewhere that you put a washer under the tensioner piston to help it apply a bit more force. Is this correct?
Hi Grant, thanks for your reply When you say between the rivet and spring do you mean slide the washer over the rivet to where I've got the arrow pointing?
When I pulled it apart before my first guess was to put a washer simply inside the top of the piston where the flat face of the rivet pushes on it.
And yes the pdf could be handy. I have read it a long tome ago but have misplaced it
04-24-2015, 02:36 PM
When you say between the rivet and spring do you mean slide the washer over the rivet to where I've got the arrow pointing?
