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When the day comes...

1070 Views 6 Replies 3 Participants Last post by  Goudy
So, as my car is now touching 140k and replacement 3.0 engines are starting to become as rare as chicken lips, i know these are prone to big end failure. Once knocking starts i'm thinking to strip the motor down myself as i'm quite handy with the tools when it comes to this kinda stuff. I dont see the point in buying used as its a gamble at the very least it could happen again, so it makes sense to repair it properly and have piece of mind knowing i have new parts in the part that purrs...

So what are we talking? At the very least, shells? What actually starts to knock? The gap between the big end and the crank? Never got round to stripping my 2.5 when that went so couldn't find the answer!

I know this is a sad subject to be talking about, nobody wants to see a dead cat at the side of the road..:(

Has anybody ever bored their 3.0 out to a 3.2? Can it even be done? Wonder what the power gains you would expect..250hp+? Lets leave the TB out for now, sure it could handle it long as the clutch isnt getting dumped round every corner!

Interesting to know - when the day comes
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I've never worked on the AJ-V6, so don't know it's own problems, but I did used to build and repair engines as part of the OEM replacement scheme.

The company I worked for had customers such as Ford, GM, Jaguar, Land Rover, Lotus. The first three being the main consumers.

Big end failure is usually down to the shells. Whether that is because they have worn away, or whether that is because there has been an oil starvation causing them to wear away. That can be the 'mains' shells between the crank and block, but is more usually the cod-rod shells as they get more abuse. The crank can wear too, but of course the shells will have worn first. If you're going to do it, get a full set of shells, don't even think about re-using the old ones.
If you take the crank out, always throw all the shells in the bin. Likewise, replace the oil spits in the block too. These can block up and restrict oil flow to the bearings.

Personally, I would leave well alone the boring out of cylinders. The better way would be to totally bore them out and then fit sleeves to your desired size. Which pistons would you then use? I think there are better ways to gain more power from the ECU. Boring it out will only lead to more problems in the head. (not your head, the car's) My opinion.
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Thanks Big Cat Little Cat for your opinion and advice :D I dont have a clue what i was thinking when i was saying about boreing out the cylinders, guessing i had a fantasy dream

So these shells, are they easily obtainable? And how much £££ are we talking? I'm guessing it will probably be worth doing the piston rings at the same time? Hoping i never have to get round to doing this, but when the time comes, i guess i'll have no choice because a blown engine wont put me off my jag that easilly :)
Jaguar Parts detail from David Manners Ltd
Connecting rod bearing (shells)

Jaguar Parts detail from David Manners Ltd

Jaguar Parts detail from David Manners Ltd
conrod (you need 6, is this a price for each??)

Jaguar Parts detail from David Manners Ltd
No use fitting new rings in a worn bore!

All the parts are available, what I'd do is the manual stripping and rebuilding, but get an engineer to measure and machine what's needed.
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Thanks Goudy. My skills can only go as far as un bolting things and putting them back together the way in which it came apart!! As you say it would probably be best getting someone who can measure up exactly what needs replacing to the required measurements. Obviously all the years of movement and friction at the least would of worn some vital parts down a smidge. I'm just thinking of the least what needs to be done instead of going down the fully rebuilding route.

Is it me or has the price of shopping suddenly got the case of herpies??
Been there and done that, though not with a car, but bikes, not the most efficient way as sods law states what you haven't done is fooked and you have to start again!

Looks like there are several piston "grades" available, I wonder if these are different oversizes?
Also, are they the type that are bored to, as in a steel liner, or like the modern nicosil plated cylinders and the pistons are microns bigger and you measure up fit the next appropriate size up to allow for wear, like you do with modern 2 stroke trials and MX bikes??

There are some good engine reconditioners out there, might be worth dropping off the bare engine and asking them to recondition it, they should warranty their work as well.
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