Hi, my girlfriends Freelander has just gone into the garage due to a loud clonking noise (didn’t hear it myself but that’s what I’m told), the mechanic has said that the transfer box/IRU has gone. He tried to disconnect the rear to just have FWD but was still making a noise. He reckons it has completely gone and the bit I can’t understand is he said it may have damaged the gear box too?!?

I’ve never worked on a Freelander, have owned discovery’s, defenders and built hybrid off roaders, so I am mechanically capable. However I have no knowledge what so ever on the Freelander.

So my questions are,

Is it possible that the gearbox is damaged?

Is it a difficult job to replace the IRU? (Haynes manual is in the Freelander at the garage so can’t have a look)

Cheers

Steve

It's not difficult but can take a day if nothing goes wrong. There are plenty of threads to search that will tell you what is involved but to make it easy on yourself if you are going to replace it would be to drop the subframe at the front

How about the possibility of a damaged gear box due to the IRD failure?

Hi @gil it is possible that the gearbox has gone - however, that would be unusual on the TD4 - it is more likely to be the IRD.

The IRD does a number of jobs and there's a number of places it can fail. The most usual is in the crown and pinion gears that drive the rear axle PTO. This is the one that if you remove the props, the car can still be used 2WD. As the noise continues, I doubt it is this. If it continued but changed a lot it could be and you could replace the rear pinion with a blanking plate to confirm.

The next most likely problem, and probably what has occurred here, is that the splines on the IRD taking drive from the gearbox have been stripped. The IRD has 2 splined shafts, one inside the other, that 'plug' into the gearbox. One takes drive from the gearbox, the other provides drive to the passenger side wheel. These are known to strip. sometimes they strip and give no noise, other times grinding noises - depends how the splines strip and whether anything continues to rub.

The other point of failure the the drivers side drive shaft support bearing. This can let go, I'd have thought with prior warning (vibration). It often results in shattered IRD cases ad gears in the diff jam.

I suppose the questions are, does the noise occur when in neutral and is the car still able to move under the power of the engine?

If the noise occurs in neutral, then the issue is gearbox/clutch related, as the IRD will not be getting any drive and thus nothing's turning to make any noise.

If the noise appears when in gear and lifting the clutch and the car does not move at all, then the splines taking drive from the gearbox is likely gone, maybe the box/clutch still.

If the car still moves with the props on, but not with them off, then the splines to the passenger front wheel are likely gone.

If the car still moves and the noise changes when removing the props, it could be the crown/pinion part of the IRD rear pinion.

Sure there's some other diagnosis theories as well - if I think of them, I'll add them!

GrumpyGel said:

Hi @gil it is possible that the gearbox has gone - however, that would be unusual on the TD4 - it is more likely to be the IRD.

The IRD does a number of jobs and there's a number of places it can fail. The most usual is in the crown and pinion gears that drive the rear axle PTO. This is the one that if you remove the props, the car can still be used 2WD. As the noise continues, I doubt it is this. If it continued but changed a lot it could be and you could replace the rear pinion with a blanking plate to confirm.

The next most likely problem, and probably what has occurred here, is that the splines on the IRD taking drive from the gearbox have been stripped. The IRD has 2 splined shafts, one inside the other, that 'plug' into the gearbox. One takes drive from the gearbox, the other provides drive to the passenger side wheel. These are known to strip. sometimes they strip and give no noise, other times grinding noises - depends how the splines strip and whether anything continues to rub.

The other point of failure the the drivers side drive shaft support bearing. This can let go, I'd have thought with prior warning (vibration). It often results in shattered IRD cases ad gears in the diff jam.

I suppose the questions are, does the noise occur when in neutral and is the car still able to move under the power of the engine?

If the noise occurs in neutral, then the issue is gearbox/clutch related, as the IRD will not be getting any drive and thus nothing's turning to make any noise.

If the noise appears when in gear and lifting the clutch and the car does not move at all, then the splines taking drive from the gearbox is likely gone, maybe the box/clutch still.

If the car still moves with the props on, but not with them off, then the splines to the passenger front wheel are likely gone.

If the car still moves and the noise changes when removing the props, it could be the crown/pinion part of the IRD rear pinion.

Sure there's some other diagnosis theories as well - if I think of them, I'll add them!

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Cheers mate, that was the sort of info I was looking for

gil said:

How about the possibility of a damaged gear box due to the IRD failure?

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Unlikely to damage the gearbox. The box survives when the IRD case explodes, so I can't see how it's going to be damaged by it making a noise.

You need to replace the IRD, and correct the initial cause of the failure, or it'll repeat again.

So budget for a reconditioned VCU and a set of identical tyres, if they're currently odd. Odd and incorrectly maintained tyres are the most likely cause of IRD failure.

The IRD is a big heavy (30kg) lump - so its unusual for Freelander maintenance. In some ways its like working on a "big" Landie

Plenty of safe working space under the car is the biggest aid to getting the IRD off easily, I've done mine from the inspection pit in my garage, wouldn't want to do it lieing on my back with everything 2 inches from my nose. The only other things you need are a socket set (with plenty of extension bars) and a bit of common.

1. Unbolt the prop from the IRD pinion - I actually took the whole props/VCU assembly off, but others just unbolts the front and lay it on the subframe or tie it up out of the way. The bolts are Torx bolts - I've got Torx sockets now, but at the time I managed it with 'regular' sockets.
2. Undo the 2 bolts holding the drivers side hub to the strut and rotate it away at the top, this extends the drive shaft, then pop the drive shaft out of the IRD and swivel it away. It will still be in the way a bit, but its easier than removing it completely.
3. Remove the Tie Bar securing the engine/IRD assembly to the subframe - 1 bolt through either end of the bar.
4. Remove the 2 coolant pipes from the IRD.
5. At this point on the L Series you can 'remove' the IRD. On the K Series your also need to remove a section of the exhaust pipe, not sure if you do on the TD4. Some people also recommend removing the subframe, I didn't on both K and L Series, don't know about TD4 - I don't know whether you 'need' to or whether it just makes removal easier.
6. The IRD is removed by undoing lots of bolts! There are at least 6 that mount it to a bracket at the drive shaft end, the bracket also needs unbolting from the engine so remove it and get it out of the way. Then there are 4 bolts that mount the IRD to the gearbox (plate). These are difficult to access and very tight. You'll need a long extension to bring the ratchet clear of the other end of the IRD and a bar over the ratchet handle to give extra leverage. This though means you can't turn the handle much, so you are doing it 1 click at a time to crack the bolts.

The IRD can then be slid away from the box to free it up (the splines needs to be fully extracted from the box) and then lowered (between engine and subframe if its still in place). Be careful though - its very heavy. Its awkward because you have to move it sideways quite a bit before you can lower it, but if you can, get a trolly jack under it.

Its a good idea to remove fluids from IRD and box before starting and creating a mess. If there's been issues inside the IRD, the oil will come out metallicy grey - if it comes out looking like old oil, then the internals are probably in good nick. IIIRC you don't need to drain the coolant system as the pipes join the system at the top, so there's minimal coolant loss - but double check that. There is a breather pipe on the IRD - I forget what I did with that, ie remove first or after, probably first.

If the oil comes out looking good and the splines are in good condition when you remove it - that would then point to a gearbox/clutch issue.

Thank you both for your help, this is why I love this page.

Going to pick it up in the next hour or so and probably have a look at it tomorrow

So tried to tow it and it is making a banging noise, sounds like the front propshaft

Sounds worse when rolling backwards

However when driving it in 1st with no acceleration it doesn’t make a noise

When mine went it made a cringing bang every meter or so - like someone was whacking it with a sledge hammer. Happened under power or just pushing the car. Pretty sure the banging was the crown/pinion gears on the rear pinion slipping.

Not sure why the noise would be different between under power or pushing - it presumably must be related to which gear is trying to turn its matching one.

This is why i stick with defenders!

GrumpyGel said:

When mine went it made a cringing bang every meter or so - like someone was whacking it with a sledge hammer. Happened under power or just pushing the car. Pretty sure the banging was the crown/pinion gears on the rear pinion slipping.

Not sure why the noise would be different between under power or pushing - it presumably must be related to which gear is trying to turn its matching one.[/Q

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gil said:

This is why i stick with defenders!

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lol, I got a bearing kit for mine (about £150 inc seals & cooler). Wasn't confident on pulling/pushing them so dropped the IRD off at a workshop to do. Also got them to remove the crown gear. So I'm running all the props etc but only 2WD. Been running perfectly fine since doing it 5 years ago and put in some sterling service - just can't take it down the beach any longer

gil said:

Hi, my girlfriends Freelander has just gone into the garage due to a loud clonking noise (didn’t hear it myself but that’s what I’m told), the mechanic has said that the transfer box/IRU has gone. He tried to disconnect the rear to just have FWD but was still making a noise. He reckons it has completely gone and the bit I can’t understand is he said it may have damaged the gear box too?!?

I’ve never worked on a Freelander, have owned discovery’s, defenders and built hybrid off roaders, so I am mechanically capable. However I have no knowledge what so ever on the Freelander.

So my questions are,

Is it possible that the gearbox is damaged?

Is it a difficult job to replace the IRU? (Haynes manual is in the Freelander at the garage so can’t have a look)

Cheers

Steve

Click to expand...

Humm just reread this is he sure it's not just a worn bush?

Madmustang said:

Humm just reread this is he sure it's not just a worn bush?

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Where abouts would a worn bush cause these symptoms. Had the rear mounts done before Christmas as it was clonking when taking up drive.

You would be surprised. It's hard to assatain what the problem is without hearing it. Can you post a video on YouTube of the sounds it makes?

So it would seem that the mechanic only disconnect the rear propshaft. I removed the crown and pinion and the noise has disappeared. Pinion is miss teeth and has worn. Going to fit a blanking plate to get by until the weather warms up.

gil said:

Going to fit a blanking plate to get by until the weather warms up

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Removing the propshafts is now an MOT fail.

The only option is to strip out the crown wheel and rebuild the IRD, with the rear drive pinion in place. The propshafts can then be refitted, and will spin with the drive from the rear diff.

Its been a WOF (MOT) fail here for a long time as the car has been significantly modified - which is why I did just that. You may also just get away with removing the crown gear and replacing the bearings in the pinion. I played safe and replaced all the bearings in the IRD but obviously that's more work and requires changing the cooler, seals etc and may not be needed.

Whether it fails or not here depends on the examiner - some will allow it through, others not. That may be because Freelanders are not that common here and examiners don't know much about them - I would have thought in the UK it will soon become knowledge among examiners to fail Freelanders with no props.

If you remove the props here, you can get the car 'certified' for the mod and it will then go through WOFs - but that costs about £200.