Just joined the team! Bought my 97 XK8 just before Xmas. Bought cheap knowing that it had "engine issues" Had the car towed to a Jag dealer, they gave me a $13k estimate that did not include tensioners etc or really knowing the engine issue. So then towed to another shop and had the front end re-built, chains, new tensioners, guides, stat and water pump. When I called to arrange pick up they said that they found a new rattle, they suggested new crank bearings and whilst engine out new oil pump.

Not having any more money at the moment I picked the car up and drove home (@ 30 miles). Does not feel like a big end bearing issue, I could under certain thottle touching, create a vibration/rattle, but it felt like a exhaust rattle, does anyone have any clue to it's possible source?

 

I would not describe bad crank bearings as a rattle, it would be a regular knock that would happen at each firing thrust on the nearest cylinder. Timing chain sounds more like rattles. Rattles can also be belt tensioner ot loose heat shields and such. Analyzing sounds with a few words is almost impossible so take this with a grain of salt. I would say that the shop should know what is going on, so unless they are incompetent, they are probably right. How many miles on this engine and is there any history to point at why it would need a new oil pump? This is fairly unusual.

 

It's not knocking, I am also not convinced about the oil pump, I spoke to a friend who suggested if it was really the big end bearings, it would have not lasted the drive home, which it did fine. It sounds more like a exhaust cowl or similiar vibration (I hope so), rather than a deep engine fault. I will have to take the plung and have another drive around tonight and try and get a better gauge on the fault. From what I've read, I can remove the timing case, dump plan and gain access to replacing the big end shells directly from the floor, is there anyway to remove the sump easily to somehow feel for the big end bearings, is there play or discoloration which I can feel or see to determine if they are at fault?

Another thread I saw talked to some faults on the torque converter, could that be the cause of the vibration/rattle?

 

What was the diagnosis of your rattle?

 

If your noise is damaged bearings on the crank anywhere, you will need to pull the engine to correct it since if the bearings are bad, the crank will need to be resurfaced before putting new bearings in. Normally, the engine running without oil is the cause of this failure, which causes the bearings to overheat and melt. Before trying this work, check around to see if the bearings are available. They are not for some models.

 

The old school of checking for a bearing or crank bearing or wrist pin bearing was to put the car in gear hold the brake and accelerate just a little. You should hear a hard knocking, if it is nonexistent look elsewhere. Does this still apply today???

 

Thanks for the comments. I did a little driving around this weekend to check the vibration/rattling.

The engine rattles a bit from the timing chain area upon first start up from cold, but then instantly is fine.

I drove around a bit, the rattle/vibration I heard on my drive back from the garage is coming from behind the passengers seat, I think it's just a cat converter of exhaust catching something. Other than that there is no rattle or vibration from the engine, surely if it was the crank or big end bearings it would be very growly by now.

My only concern is that after I've been driving some 20 mins or so, when i stop at a light, the oil pressure dips to red, the slightest press on the throttle and it returns to dead center fine. Is this an issue? Could it be related to the reported fault by the garage?

 

If I recall the pressure gauge in the car is like a placebo. I think if you check around you will find that the sending unit on your car needs to be changed. I had the same problem on mine so do not panic yet.

 

The garage did claim to fit a new pressure sender, so either it is accurate and the pressure does dip a little a low rpm, or it's still faulty. The engine does seem to run fine. Is there anyway to confirm if the bearings are shot, other than taking the sump off and making some type of physical inspection? Or just continue to drive around listening to see if any rattle starts to get occur?

 

No sure way other than taking it apart. What I do is every time the oil is changed I will take the time to turn the radio off and listen to the engine as someone starts it for me. I found in the past (the early years) that when a bearing is worn you will hear it just after an oil change. No noise then I would not worry about it. I also found that when I used 10w30w oil in the winter I would hear the chains just for a moment when starting. I changed to synthetic (5w30w?) and I no longer have the noise. As for the gauge I remember having the same problem, replaced the sensor and it was fixed. I would not be concerned until it is looked at and you know for sure. My indicator is always in the middle and the only time it goes to low is when the engine is turned off. The Jaguar mechanic told me it was a strange setup.

 

The temp and pressure gauges on most cars are not correlated to the actual measurement. Rather they act more like idiot lights and respond only when the readings are out of previously established acceptable range of performance. Dial readings do not measure a linear [unit for unit] change in sensor activity. The two are not correlated.

For example, an oil gauge will remain dead center as long as the oil pressure is anywhere between say 20 psi and 60 psi. (reading used for example purposes only). It will only move off center if the sensor data is beyond either side of those numbers. This is why the engine water temp dial stays in the center of the gauge dial, long after the car has been shut off and the engine cooled down. If it does move to the hot side, I guarantee you, it has already crept up through the "little bit too hot range". and is almost ready to blow off your 15 psi cap.

You can check you sensor performance by reading its ohm resistance and comparing it to factory OEM specs. I don't know the Jaguar numbers.

gordo

 

Which is exactly why those things need to be replaced with real gauges

 

There is a way to confirm the oil pressure, just go to the garage and get them to put a guage on it and read the pressure. If it is good, it is unlikely the main bearings are shot unless you hear the telltale knocking sound they make.

 

The "killer symptom" for bearing shell failure is white metal particles in the oil when you drain it out. They sparkle in the sunlight and I know 'coz I have seen it !! Also if you remove the sump you will see them in the sludge.

Main bearings will rumble and there will be a knocking noise if the big-ends have gone. Your oil light sound suspicious if it goes when you blip the throttle. Having said all that, bearing failures like this are very uncommon unless the car has been subject to quite severe neglect.

 

I had upper tensioners changed with new steel ones and I still have this same sound as I did 8,000 miles ago before the upper tensioners were replaced at 34,500 miles. Is this a timing chain sound at startup that is heard or could this be some thing else, a VVT that takes a second to get oil to it. What is this sound???

Video & sound link of the upper right side by the VVT
http://www.youtube.com/watch?v=RLWGZVF4OrM
Under the front of the car
http://www.youtube.com/watch?v=mLynasgUpuc

 

I can't tell from your videos what sound you are referencing. However, if you are hearing a single click or tap about 15 seconds after startup, when the engine rpm is raised above 1000 rpm, it is probably the VVT cylinder filling up with pressurized oil and pushing/turning on spiral groovs, eventually seating itself at the end of its travel. It sounds like a metal to metal stop, and this maybe the click you are hearing. Each VVT only clicks once, so if you are hearing a series of closely spaced clicks, or a pattern; then it is not the VVT.

If you need more info, go to your JTIS and read VVT design and function. Or you may find this in search. This issue has been discussed a couple of times at length.

 

The first 2 seconds of clatter / rattle at startup is what is the ??

 

The 'clatter' I hear on your video does not sound significant enough to cause me concern. It sounds like some lifters pumping up, and the chains running a little loose while waiting to be tensioned by oil pressure.

 

If you've already had the tensioners replaced and you still get clattering like that (I practically jumped out of my seat when I heard it), then there could be some kind of oil starvation in the engine; some kind of gallery clogged with who knows what, preventing the oil from getting to where it should during startup.

Is it worse in the AM with a stone cold engine? That could be an indicator of oil not getting to where it needs to be quickly enough. You're doing some damage to that engine each time you start it, by the sounds of things.

 

Sound is Only heard when car sits for more than 10 hours, is this normal? Lower tensenors / guides not done only 34K miles and the uppers looked fine, engine real clean but we did replace upper secondary tensioners.