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Hello folks,

As the title implies, my P38 diesel has lost drive and is leaking transmission oil from the bell housing. I am assuming this is either a leaking/cracked torque converter or the input shaft seal on the gearbox.

I am competent with a toolkit (spent twenty odd years fixing jet aircraft) but I don't have access to a vehicle lift/ramp, just normal trolley jack and axle stands.

I have a few questions I am hoping the knowledge and experience on here might be able to help with:

1) Is removal of the transmission feasible at home?

2) Are any special tools or jigs required?

3) Should I remove the transfer box first to reduce weight or am I just inviting more problems and would be better off leaving it all as one unit?

I had the vehicle transported to my parents place as they have more space than me and have not yet been back to see how low the transmission fluid level has got. I carried out a fluid and filter change (along with new transmission oil cooler and pipes) about a year ago so the majority of the fluid was replaced. If the fluid level hasn't dropped too low is the box likely to be ok or will I have knackered the internal clutches?

If I do need a replacement box, has anyone any experience of these:
Recon Gearbox from Wales

Many thanks for any help and advice given. This could be the end of the journey but I am reluctant to write it off as I have invested a lot of time and money into it now (suspension, brakes, cooling, electrics, someof the interior) and I will never be able to afford one again.

Regards,

Si.

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Update, checked oil level and it's off the bottom of the dipstick. Removed the drain plug, it's brown with tiny dark particles in it. So looks like the box is toast.

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I recently replaced my gearbox. For access, I put the suspension on high then put my calibration blocks in so it wouldn't drop. I then jacked the front up and put ramps under the front wheels and strapped the wheels to the ramps so it can't roll. Don't forget that once the propshafts are disconnected, there's nothing to stop it rolling.....

Using a trolley jack under the gearbox and two of us (I ratchet strapped the gearbox to the trolley jack), it came out complete with transfer case but as it was only the gearbox we were changing they had to be separated anyway. When it came to fitting the new one, it went on without the transfer case and we fitted that once the box was on. With the crossmember out, getting to the bolts that hold the two together is a lot easier too.

I got a gearbox for mine from Dave at East Coast Range Rovers (07527 953807), £300 delivered on a pallet.

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Thanks for that, very much appreciated.

Do you know if there any truth in the ebay ads claim that the later 4.6 box is stronger and a direct replacement (with appropriate bell housing and torque converter) for the diesel? Same gear ratios?

I shall give that place a call.

Cheers,
Simon.

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you can put the hp22 in with some modifications, it's a recommended upgrade. you can not put the hp24 in as the torque converter is to big and will not fit in the bell housing . you will need the old bell housing to fit to the hp22 and drill a hole in the housing to do up the bolts on the flex plate , you also need a different flex plate, boss and bolts (ashcrofts is where you get this stuff) as the original only has 3 bolts and the hp22 has 4
PS you also have to get the vehicle remapped to suit the bigger torque converter or it will be sluggish as the turbo doesn't work properly . hope that helps .
PSS you can fit the internals from the hp24 into the hp22 but you still need the hp22 converter and oil pump.

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4HP24 from the 4.6 is longer by about 15mm but the tailshaft housing is 15mm shorter so the overall length is the same if you are using your original torque converter. To replace the original 4.0 litre 4HP22 with a 4HP24 from a 4.6 I had to change a spacer behind the flex plate for a thinner one to allow for the larger torque converter but that was all. No idea on the diesel as it only has a 3 bolt flex plate and not the 4 bolt on the V8 versions. I know Dave has quite a number of 4HP24 gearboxes all sitting on pallets but he tends to not keep the 22s as he will always fit a 24 to a V8 if it needs a gearbox. However, I got a 4HP22 from a diesel from him a few weeks ago that I took to an owner in Spain. Give him a call and he will be able to tell you exactly what bits you will need to change and what you can retain.

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Probably best to fit a replacement torque convertor at the same time if the fluid is full of bits?

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My replacement gearbox from Dave came complete with the Torque converter.....

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I personally would remove the engine as trying to refit gearbox with converter in is a real nightmare ---- mate did his DSE and broke converter and pump ---- All because he didn't remove the engine

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That can happen if the TC isn't fully home when you fit the gearbox. RAVE says to stand the gearbox on end when fitting it, which I did, and it slides onto the splines but is a bit wobbly, turn it, it drops about half an inch with a satisfying clunk, is fully engaged and no longer wobbles. As the engine is tilted down at the back, gravity helps with holding the TC in place but a bit of wood shoved in the bellhousing inspection hole ensures it doesn't slip out.

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I have ordered a recon unit from Ashcroft Transmissions. They are building me an -065 suffix ZF4HP24 box with a diesel bell housing and torque converter for the standard cost of a straight rebuild.
This is not a job I want to repeat and my original transmission was in really good condition (flushed last year following a cooler replacement and fluid had stayed clean since) up until the moment the seal at the torque converter gave way and it ran low.
Just a 3 week lead time to deal with but comes with 12 month warranty and all new clutches etc...

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don't forget you have to get it remapped or it will be slow to drive the bigger torque converter.

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Will it? I've changed the original 4HP22 on my 4.0 litre V8 for a 4HP24 with the larger torque converter and other than changes being smoother and at a couple of hundred revs higher, there's no difference.

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it's not a turbo diesel either Richard, the mapping does not suit the bigger convertor, it changes gears at the wrong time and has lots of lag will drive like dog, slow and sludgy. if you read the reviews it states that it requires remapping.

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Or shift it manually when you want a bit more pep.

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You can't fit the bigger V8 torque converter to the diesel. The only TC that fits into the diesel bellhousing is the diesel TC.
At one stage Ashcrofts used to offer an uprated diesel TC (manufactured by someone else I think) but they have stopped doing them.
It looks identical to the standard one. I suspect it maybe just a thicker fluid in a standard one that some enterprising chap modified.
Mapping the diesel does raise the gear change points. Why exactly, I don't know.

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Good point, he's using a diesel torque converter and bell housing on a 4HP24 so there won't be any change, just a stronger gearbox. The V8 bellhousing wouldn't bolt up to the diesel engine and the larger TC probably wouldn't fit inside the diesel bell housing. I understand the diesel TC and flex plate has only 3 bolts compared with 4 on the V8 so to use the larger TC would involve quite a bit of modification to lots of bits.

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I think I am also confusing the torque converter with the viscous coupling. I remember there was a discussion on the other site about putting new silicone fluid in the viscous coupling, which are no longer available new. The characteristics of the coupling can be changed by using a different viscosity oil. A thicker oil for less slip for off road work.
When I had my HP24 fitted by Ashcofts I got them to fit an uprated diesel TC. I am not sure how it differs exactly, whether different internals off another L/R model. The fluid in the TC will be transmission fluid won't it?

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dave3d wrote:

The fluid in the TC will be transmission fluid won't it?

Yes it is, that's why you check the level with the engine running so the torque converter is filled.

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sorry i have been away . the torque convertor from the 22 will fit in the diesel bell housing, the 24 is to big and will physically not fit . you have to modify the diesel housing by drilling a hole in it to access the bolts on the flex plate which also has to be replaced as the diesel one only has 3 bolts.
there is no advantage to just put bigger clutch pack in the diesel trans as the small oil pump and torque converter is what fails in these boxes.