Jaguar Forum banner

21 - 40 of 42 Posts

·
Administrator
Joined
·
26,000 Posts
What I meant was ECM have time to adjust the fuel injection and timings so that forces acting on crankshaft from connecting rods matches the resistance from gearbox. It’s not a shock when engine is set to accelerate and instead of an smooth transition a rotational shock is exerted on the crank end.
I'd agree that the transition is smooth when you lift off, but the ECU would have no idea when a braking load was going to arrive. Since it'd already cut the fuel, there would be nothing it could do to soften the blow anyway?
 

·
Registered
Joined
·
63 Posts
I thought the crankshaft issues were because of the bearings rotating within the big end, covering the lube hole?

Correct as far as I know. I also follow another forum which details many, many instances of the 3.0 TDV6 crank failures in the Landrover Discovery version. The possibility of such a random failure which effectively writes off the vehicle, persuaded me to go for the 2.2 engine. Pick up any of the stories attached and you will see why. Links to Discovery TDv6/SDv6 Failure Reports
 

·
Registered
Joined
·
5,639 Posts
This should have been covered in the design. 5.0 is a completely different engine and for sure the crankshaft and many other parts are stronger. Also the harmonics due to those impacts are different as well as tolerances due to being a higher performance engine.
The idea was that harsh changes will accelerate the crankshaft failures or spinning a bearing.
Go and drive an R-S in Sport/Dynamic and on the paddles. You'll get what I mean.
 

·
Registered
Joined
·
808 Posts
Go and drive an R-S in Sport/Dynamic and on the paddles. You'll get what I mean.
I know what you mean. XFS in Sport/Dynamic will kick hard as well. When it comes to forces, torque maters not the HP. And XFR-S only has 13%more torque at higher RPMs compared to XFS.
We talking about a flaw in 3.0D engine and daily driving's that involves hundreds or those shocks daily instead of a smooth power transmissions.
 

·
Administrator
Joined
·
27,849 Posts
So..................there are many vehicles with auto transmissions, and quite a few where the shifts can be "sped up" to the point of real harshness in Sport or Track mode.

But I don't hear of broken cranks on those.....................

And the vast majority of 3.0D broken cranks were in Land or Range Rovers, not marques known for needing the ultimate rapid-fire gear changes.
 

·
Registered
Joined
·
808 Posts
So..................there are many vehicles with auto transmissions, and quite a few where the shifts can be "sped up" to the point of real harshness in Sport or Track mode.

But I don't hear of broken cranks on those.....................

And the vast majority of 3.0D broken cranks were in Land or Range Rovers, not marques known for needing the ultimate rapid-fire gear changes.
I think Graham‘s point was when the gearbox oil needs changing and people don’t it can contribute to premature crankshaft related issues.
 

·
Registered
Joined
·
18,452 Posts
I think Graham‘s point was when the gearbox oil needs changing and people don’t it can contribute to premature crankshaft related issues.
This is one of those theories that can never be un-proven. For example . . . .
I have an elephant repellent hanging in our garden and it's brilliant. So effective.
 

·
Registered
Joined
·
808 Posts
This is one of those theories that can never be un-proven. For example . . . .
I have an elephant repellent hanging in our garden and it's brilliant. So effective.
I see your point but these engines suffer from crankshaft issues in higher mileage and gearbox changes becomes harsh when oil needs changing. So your example works only you have elephants living near your garden.
 

·
Registered
Joined
·
18,452 Posts
I see your point but these engines suffer from crankshaft issues in higher mileage and gearbox changes becomes harsh when oil needs changing. So your example works only you have elephants living near your garden.
OK, but this theory is just that and can never be verified. Seems plausible but so is the theory that the moon landings were filmed in a studio.
 

·
Registered
Joined
·
808 Posts
OK, but this theory is just that and can never be verified. Seems plausible but so is the theory that the moon landings were filmed in a studio.
Agreed. I think people change the gearbox oil anyway to protect it and they might save their engine in longer term.
 

·
Registered
Joined
·
5,639 Posts
I know what you mean. XFS in Sport/Dynamic will kick hard as well. When it comes to forces, torque maters not the HP. And XFR-S only has 13%more torque at higher RPMs compared to XFS.
We talking about a flaw in 3.0D engine and daily driving's that involves hundreds or those shocks daily instead of a smooth power transmissions.
I was thinking more about the severe upshifts the R-S is capable of. It has the F-type quickshft and the change from 6000RPM to the RPM of the next gear up is instantaneous.
 

·
Registered
Joined
·
808 Posts
I was thinking more about the severe upshifts the R-S is capable of. It has the F-type quickshft and the change from 6000RPM to the RPM of the next gear up is instantaneous.
I am sure they use higher rated parts in R-S even if they look the same and tighter tolerances.
 

·
Registered
Joined
·
2,707 Posts
Discussion Starter #34
Isn't it the bearings which are what actually cause the problem? Oil dilution aside, I thought you meant the shock from the harsh gear changes would contribute towards causing the bearings to spin, which would then subsequently cause premature failing of the crank. I didn't think you meant direct shock on the crank?

Could the 5.0 and other manufactures have different designs which prevent the bearings from rotating?
 

·
Registered
Joined
·
808 Posts
Isn't it the bearings which are what actually cause the problem? Oil dilution aside, I thought you meant the shock from the harsh gear changes would contribute towards causing the bearings to spin, which would then subsequently cause premature failing of the crank. I didn't think you meant direct shock on the crank?

Could the 5.0 and other manufactures have different designs which prevent the bearings from rotating?
Yes. It’s just my way of thinking. The bearings can spin in their place without causing problems. The vibrations of crankshaft could cause them to spin more and fail.
 

·
Registered
Joined
·
5,639 Posts
Isn't it the bearings which are what actually cause the problem? Oil dilution aside, I thought you meant the shock from the harsh gear changes would contribute towards causing the bearings to spin, which would then subsequently cause premature failing of the crank. I didn't think you meant direct shock on the crank?

Could the 5.0 and other manufactures have different designs which prevent the bearings from rotating?
The 3.0 didn’t initially, but did later on.
 

·
Registered
Joined
·
5,639 Posts
I am sure they use higher rated parts in R-S even if they look the same and tighter tolerances.
Really. We are talking JLR here. :D
 

·
Registered
Joined
·
808 Posts
Really. We are talking JLR here. :D
Really. They are tables in missing section of WM that they says which grade of head should be matched which grade of engine block and crankshaft for different models. By the grade I mean different tolerance bands.
 

·
Registered
Joined
·
2,707 Posts
Discussion Starter #39
The 3.0 didn’t initially, but did later on.
I've heard this before but despite persevering I cannot find anything solid to support a design change of the crank (or such) which would prevent the spinning? On the Facebook forums I've asked some of those who proclaim to be Jaguar techs, but they never answer. I really wish I could find a definite answer to put my mind at rest. Not that I'm paranoid or anything....
 

·
Registered
Joined
·
808 Posts
I have seen at least one failing and I don’t blame the crankshaft or engine. I think it was lack of proper lubrication. The only clue I have is that there was an oil leak from secondary turbo “feed“ pipe. Potentially dropping pressure at high demands. The oil pressure test was within normal range just before I start the rebuild. All bearings were perfectly worn and plenty of life left. Only 1 was gone. Inside engine was really clean, No blockage on oil gallery feeding to failed bearing. Oil pump was fine. Shavigs were caught by pickup pipe (that has a magnetic net) Piston rings, pistons, cylinder wall, everything was just in perfect worn shape that I didn’t change them. I only ground the crankshaft and changed one con rod in addition to single use bolts, seals and accessories. I think it was oil starvation or oil dilution. Both could be addressed by shorter oil change intervals. I still have a sample of original oil If anyone is interested.

On the other hand, when you extract more HP out of the same block, you are actually reducing its life because you are pushing it to its design limits.

if your car has been looked after and any abnormal noise has been addressed, there is no need to worry at all. 15k service intervals however seems to be a joke unless you only drive on motorways.
 
21 - 40 of 42 Posts
Top