I have been experiencing some strange up-shift issues on a 4HP24 box since early last week (there but less noticeable on down-shift). Initially, a couple of occasions where shift seemed to delay (revs rise higher than usual and slower shift), but by the weekend this had become regular. I would have looked at oil change over the weekend, but had arranged a couple of days with the boat in Plymouth, so decided to live with it for a week. I checked the oil level and this appears ok - perhaps even slightly high by 3-4mm but this could have been due to a less than 100% level surface. (I've not added any since buying in Feb 2013 and level has been constant) Oil is clean and doesn't smell burnt. However, when towing the boat back on Sunday, it became apparent that changing up from 3rd to 4th was becoming hard work for the box and a couple times it seemed not to engage 3rd at all (holding selector at 3rd on selecting D for steep inclines was like selecting 'N') and this was accompanied by a burning smell! The boat isn't particularly heavy - perhaps 1100kg with trailer fuel etc. The answer seemed to be to hold in 2nd when pulling away, let the revs rise higher than usual and then ease off whilst selecting D as the box would shift to 3rd, seek for perhaps 1.5 to 2 seconds and then pickup 4th. Rechecked oil and all much as before - no burnt smell colour fine...

I have a day off tomorrow and have picked up fresh oil this morning and have a transmission filter on its way so will try oil change before going too far, but further testing (without trailer) still results in a 1.5-2 second delay changing between 3rd & 4th, but bites/drives fine in all gears. Symptoms are the same in Sport, but driving hard and holding 3rd manually for a longer period before shifting selector to D whilst easing off the throttle does seem to shift to 4th more quickly which made me think it was more likely a torque converter issue.

I'm guessing that when I change the oil, that which is in the torque converter is also not going to drain... Am I wasting my time and is a 2nd hand transmission for £300ish a better bet? I have changed a GM400 on an XJS before, so reckon I can do in a day... The downside is the nearest I can find with a quick search is about 80 odd miles away so a 160 mile round trip with dodgy box! I should add that the vehicle is just shy of 200K, so a transmission oil change is perhaps to be expected!

You can try changing the oil and filter and sticking a bottle or two of Lucas in it, sounds like a sticky valve block. It may cure it it may not, but £50.00 for oil and Lucas is better than the price of a new box and the pain of fitting it.

As Wammers said, sticky valve block, it will not be the torque convertor. Oil & filter changes are called for at 24K intervals. Lucas Transmission Fix sorted mine for the time being.

Thanks guys - the previous owner didn't seem to scrimp on servicing going by the invoices, so I'd assume it has been done. I'm only covering between 6-8K annual miles currently so had planned a good service before the winter anyway. Will add a bottle of Lucus transmission fix to my shopping list today!

Rob4x40 said:

Thanks guys - the previous owner didn't seem to scrimp on servicing going by the invoices, so I'd assume it has been done. I'm only covering between 6-8K annual miles currently so had planned a good service before the winter anyway. Will add a bottle of Lucus transmission fix to my shopping list today!

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Garages rarely if ever change the oil in the auto box.

Datatek said:

Garages rarely if ever change the oil in the auto box.

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Yep, even when they charge for it.

Well how wrong was I? The oil in the dipstick may have been pink, but that in the gearbox certainly wasn't! Perhaps it's 1997 oil after all...

New oil in, but had to order the Lucas, so probably won't get until Monday... 5.25L of old oil drained and 5L new oil in, so will test as is and if ok, leave the .25L until the Lucas goes in to save having to drain some out... Waiting for it to settle before I fire up and check level. Thanks for the tips, will let you know how it works out.

drain the oil cooler and pipes..zf24 holds about 11litres from empty...thats what mine took..no point in doing half a job..

zen said:

drain the oil cooler and pipes..zf24 holds about 11litres from empty...thats what mine took..no point in doing half a job..

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You cannot drain the torque converter. The Auto gearbox holds 9.7 litres from empty. Thing to do is drain and fill then run car for a couple of weeks and repeat.

wammers said:

You cannot drain the torque converter. The Auto gearbox holds 9.7 litres from empty. Thing to do is drain and fill then run car for a couple of weeks and repeat.

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That's my plan. I put the front on ramps to pull as much back as I could from the cooler, but didn't really want to take that out too due to time. I'll flush again in a couple of weeks after I've treated and might then look to drain more. Given the state of it a couple of extra changes won't hurt.

Still the same issue at the moment, but will try the lucas when it turns up...

for me i will just put the transmiision oil after flashing the whole system ; drive for a month of 500 to a 1000 miles , secondly drain it and put lucas oil and a bottle of two bottle snake oil again depending how bad if the driving with the new oil , and all is done

Rob4x40 said:

That's my plan. I put the front on ramps to pull as much back as I could from the cooler, but didn't really want to take that out too due to time. I'll flush again in a couple of weeks after I've treated and might then look to drain more. Given the state of it a couple of extra changes won't hurt.

Still the same issue at the moment, but will try the lucas when it turns up...

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Drain and flush again before adding the Lucas, it can take a few good runs before the Lucas frees things off, I'm on the third dose of treatment and the shifts got better each time, just the ocassional hard shift into top now, before it was flaring on 2nd to 3rd and 3rd to top and down shifts on a hill were dangerous

Datatek said:

Drain and flush again before adding the Lucas, it can take a few good runs before the Lucas frees things off, I'm on the third dose of treatment and the shifts got better each time, just the ocassional hard shift into top now, before it was flaring on 2nd to 3rd and 3rd to top and down shifts on a hill were dangerous

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Well, the gearbox is no better and with some long road trips coming up towing, I need to sort this. Last day of work tomorrow before 2 weeks off and some job hunting, so an opportunity to fix. 2 bottles of Lucas haven't fixed yet.

Going to order another filter and bottle of Lucas for next week and have 1 more go, but now thinking on plan B...

Anyone swapped a 4HP24 on their own before? Looks a heavy lump and even with a couple of jacks, axle stands, ramps and an engine crane, not sure if this is going to be very easy... I can get a good box with warranty for a couple of hundred notes about 70 miles away from where I am and given the 202000 miles on the clock, I feel that this may be the best route...

Rob4x40 said:

Well, the gearbox is no better and with some long road trips coming up towing, I need to sort this. Last day of work tomorrow before 2 weeks off and some job hunting, so an opportunity to fix. 2 bottles of Lucas haven't fixed yet.

Going to order another filter and bottle of Lucas for next week and have 1 more go, but now thinking on plan B...

Anyone swapped a 4HP24 on their own before? Looks a heavy lump and even with a couple of jacks, axle stands, ramps and an engine crane, not sure if this is going to be very easy... I can get a good box with warranty for a couple of hundred notes about 70 miles away from where I am and given the 202000 miles on the clock, I feel that this may be the best route...

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It has been done, bloody heavy and an awkward shape with the transfer box attached, better perhaps to take the transfer box off first, then the gearbox.

Datatek said:

It has been done, bloody heavy and an awkward shape with the transfer box attached, better perhaps to take the transfer box off first, then the gearbox.

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Yes, thanks. I'd need to do that anyway as the replacement would be the auto box only so would re-use the transfer.

It looks like the transmission weighs in at around 76kg, so thought it would be doable, but lifting is one thing, balancing whilst laying under the motor and aligning bolts is another!

Rob4x40 said:

Yes, thanks. I'd need to do that anyway as the replacement would be the auto box only so would re-use the transfer.

It looks like the transmission weighs in at around 76kg, so thought it would be doable, but lifting is one thing, balancing whilst laying under the motor and aligning bolts is another!

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Make sure the torque convertor is wedged in place before you drop the box and that it is correctly located and held in place when refitting or you will break off the oil pump drive lugs.
I thought it was a bit more than 76Kg but you may be right.

Datatek said:

Make sure the torque convertor is wedged in place before you drop the box and that it is correctly located and held in place when refitting of you will break off the oil pump drive lugs.
I thought it was a bit more than 76Kg but you may be right.

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Thanks, I'll look out for that!

I thought it would be a bit more too and I'm guessing that's a dry weight, but guess it won't be far off - found on a BMW site and as far as I'm aware the weights will be close.

Not really looking forward to the job, but local garage reckon 8 hours/£300 to change

Rob4x40 said:

Thanks, I'll look out for that!

I thought it would be a bit more too and I'm guessing that's a dry weight, but guess it won't be far off - found on a BMW site and as far as I'm aware the weights will be close.

Not really looking forward to the job, but local garage reckon 8 hours/£300 to change

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£300 for 8 hours sounds good to me!

kooky_guy said:

£300 for 8 hours sounds good to me!

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That's just the labour, so likely £400 ish with oil, filter etc. Not a main dealer or LR specialist, but they're very good/fair. I guess the thought of £300 hurts and makes me think I can do it in 4 for just the cost of the oil, filter etc... (Plus the fact that I'm unemployed for a couple of weeks in 24 hours makes me cautious!)