Splitting RV8 and 4HP22 box
Discussion
Hi all. I've had many an engine and gearbox apart over the years but never an auto. I've removed a 3.9i RV8 with the ZF 4HP22 box from an old Disco and these will be going into my Defender shortly.
The engine has a few oil leaks on it so it obviously makes sense to (try and) cure those before I refit. There's a lot of oil around the sump, which may well just be the sump gasket, but I'm wondering whether I may as well replace the rear crank oil seal whilst I'm at it.
So, if I unbolt the bellhousing, does the box (and the TC?) just lift off the back of the engine as with a manual, and slide back on after, or are there any snags/pitfalls/wizardry involved in replacing them?
Thanks.
The engine has a few oil leaks on it so it obviously makes sense to (try and) cure those before I refit. There's a lot of oil around the sump, which may well just be the sump gasket, but I'm wondering whether I may as well replace the rear crank oil seal whilst I'm at it.
So, if I unbolt the bellhousing, does the box (and the TC?) just lift off the back of the engine as with a manual, and slide back on after, or are there any snags/pitfalls/wizardry involved in replacing them?
Thanks.
Do not pull it apart.
The torque converter has an oil pump drive connection to the gearbox which will be damaged if you pull it apart.
Remove the tin cover plate at the base of the bell housing. Looking in you will see the back of the flex plate which drives the TC. Rotate the engine until you see the first bolt head. Remove the bolt and rotate again to find the next bolt (4 I believe).
With all the bolts out you can remove the box but support the TC as soon as you can. Normal method is to bolt a strap across the bell housing to stop the TC falling out.
Steve
The torque converter has an oil pump drive connection to the gearbox which will be damaged if you pull it apart.
Remove the tin cover plate at the base of the bell housing. Looking in you will see the back of the flex plate which drives the TC. Rotate the engine until you see the first bolt head. Remove the bolt and rotate again to find the next bolt (4 I believe).
With all the bolts out you can remove the box but support the TC as soon as you can. Normal method is to bolt a strap across the bell housing to stop the TC falling out.
Steve
The TC has 2 slots in the spigot that fits into the gearbox. The gearbox input seal seals on this spigot & the cutouts engage with & drive the gearbox fluid pump.
The TC is free to slide & will happily slide off the input shaft & fall onto the floor so as already said, use something to stop it doing that.
They are very heavy & contain a lot of fluid which will go all over the floor.
If it DOES fall off then lining the splines on the input shaft with those inside the TC can be an utter PITA. The LR manuals show it being done with the gearbox horizontal & a couple of threaded handles screwed into two of the raised bosses on the front of the TC. It does work, but clear the area of small children & those easily offended by loud swearing before starting to put it back on!
When refitting the box to the engine the TC MUST be on the gearbox AND seated to the correct depth as measured from a straightedge laid across the bellhousing mouth to the front of any of the four raised bosses.
You will find this in this link (mine's on a RRC 3.5EFi & is 51mm & I've had the box off a couple of times. The TC fell off the first time & I took it off the last time as I was sorting out some gearbox leaks)
https://www.ashcroft-transmissions.co.uk/automatic...
If you don't do this then whilst the gearbox will very likely bolt up to the engine you will damage the pump in the box that the slots in the TC spigot engage with. No pump=no fluid pressure=no drive & you get to take it all off again to fit a new pump.
The TC is free to slide & will happily slide off the input shaft & fall onto the floor so as already said, use something to stop it doing that.
They are very heavy & contain a lot of fluid which will go all over the floor.
If it DOES fall off then lining the splines on the input shaft with those inside the TC can be an utter PITA. The LR manuals show it being done with the gearbox horizontal & a couple of threaded handles screwed into two of the raised bosses on the front of the TC. It does work, but clear the area of small children & those easily offended by loud swearing before starting to put it back on!
When refitting the box to the engine the TC MUST be on the gearbox AND seated to the correct depth as measured from a straightedge laid across the bellhousing mouth to the front of any of the four raised bosses.
You will find this in this link (mine's on a RRC 3.5EFi & is 51mm & I've had the box off a couple of times. The TC fell off the first time & I took it off the last time as I was sorting out some gearbox leaks)
https://www.ashcroft-transmissions.co.uk/automatic...
If you don't do this then whilst the gearbox will very likely bolt up to the engine you will damage the pump in the box that the slots in the TC spigot engage with. No pump=no fluid pressure=no drive & you get to take it all off again to fit a new pump.
Edited by paintman on Thursday 23 August 18:26
paintman said:
The TC has 2 slots in the spigot that fits into the gearbox. The gearbox input seal seals on this spigot & the cutouts engage with & drive the gearbox fluid pump.
The TC is free to slide & will happily slide off the input shaft & fall onto the floor so as already said, use something to stop it doing that.
They are very heavy & contain a lot of fluid which will go all over the floor.
If it DOES fall off then lining the splines on the input shaft with those inside the TC can be an utter PITA. The LR manuals show it being done with the gearbox horizontal & a couple of threaded handles screwed into two of the raised bosses on the front of the TC. It does work, but clear the area of small children & those easily offended by loud swearing before starting to put it back on!
When refitting the box to the engine the TC MUST be on the gearbox AND seated to the correct depth as measured from a straightedge laid across the bellhousing mouth to the front of any of the four raised bosses.
You will find this in this link (mine's on a RRC 3.5EFi & is 51mm & I've had the box off a couple of times. The TC fell off the first time & I took it off the last time as I was sorting out some gearbox leaks)
https://www.ashcroft-transmissions.co.uk/automatic...
If you don't do this then whilst the gearbox will very likely bolt up to the engine you will damage the pump in the box that the slots in the TC spigot engage with. No pump=no fluid pressure=no drive & you get to take it all off again to fit a new pump.
Thanks (once again!) Paintman.The TC is free to slide & will happily slide off the input shaft & fall onto the floor so as already said, use something to stop it doing that.
They are very heavy & contain a lot of fluid which will go all over the floor.
If it DOES fall off then lining the splines on the input shaft with those inside the TC can be an utter PITA. The LR manuals show it being done with the gearbox horizontal & a couple of threaded handles screwed into two of the raised bosses on the front of the TC. It does work, but clear the area of small children & those easily offended by loud swearing before starting to put it back on!
When refitting the box to the engine the TC MUST be on the gearbox AND seated to the correct depth as measured from a straightedge laid across the bellhousing mouth to the front of any of the four raised bosses.
You will find this in this link (mine's on a RRC 3.5EFi & is 51mm & I've had the box off a couple of times. The TC fell off the first time & I took it off the last time as I was sorting out some gearbox leaks)
https://www.ashcroft-transmissions.co.uk/automatic...
If you don't do this then whilst the gearbox will very likely bolt up to the engine you will damage the pump in the box that the slots in the TC spigot engage with. No pump=no fluid pressure=no drive & you get to take it all off again to fit a new pump.
Edited by paintman on Thursday 23 August 18:26
I'm starting to think that this leak is DEFINITELY the sump gasket and not the crankshaft seal!!
I agree.
Although the pressed steel sump can also be a pig to get to seal, esp if it's had some on & offs in the past as the mating face can deform esp if overtightened,
Finally,after reading a Rover SD1 forum. on I RTVd the sump, allowed a few minutes for it to start to go off & then laid the gasket on it. Followed by a flat piece of contiboard. Left overnight for it to cure & then fitted to the engine with a smear of rtv. Clean the bolts, use thread sealant & torque to the correct figure. Not had a problem since (so far!)
Although the pressed steel sump can also be a pig to get to seal, esp if it's had some on & offs in the past as the mating face can deform esp if overtightened,
Finally,after reading a Rover SD1 forum. on I RTVd the sump, allowed a few minutes for it to start to go off & then laid the gasket on it. Followed by a flat piece of contiboard. Left overnight for it to cure & then fitted to the engine with a smear of rtv. Clean the bolts, use thread sealant & torque to the correct figure. Not had a problem since (so far!)
I've been pondering this since I first posted and am talking myself into a state of mild panic over attempting this and cocking it up! I'm a fairly competent spannerer but this task is bugging me.
For context/ability level, I've successfully removed the entire engine/box/gubbins from a rusty D1 and I'll be transplanting into my Defender, which I'm not that fazed by other than the amount of work it will involve being just a slitghtly-ageing me, a driveway and no 4-poster or pit. I've had the existing 3.5 V8 out of the Defender twice in the past, both times to fit a new gearbox, the LT95, which weighs about 99% of the total mass of planet earth.
A question: if I support the engine and box (bear in mind they're out of the car now) and follow the steps above to unbolt the flex plate etc, then strap the 'box in place and lift the engine away from the box, leaving it where it is whilst ensuring that the TC stays where IT is, will I be able to simply offer the engine back up to the box and bolt everything back up? Or are all those checks and measurements and fitments still required?
Pardon the apparently-dumb questions but I've only ever done this with manual boxes and clutches, and I'm trying to visualise the tasks involved in doing it with an auto.
For context/ability level, I've successfully removed the entire engine/box/gubbins from a rusty D1 and I'll be transplanting into my Defender, which I'm not that fazed by other than the amount of work it will involve being just a slitghtly-ageing me, a driveway and no 4-poster or pit. I've had the existing 3.5 V8 out of the Defender twice in the past, both times to fit a new gearbox, the LT95, which weighs about 99% of the total mass of planet earth.
A question: if I support the engine and box (bear in mind they're out of the car now) and follow the steps above to unbolt the flex plate etc, then strap the 'box in place and lift the engine away from the box, leaving it where it is whilst ensuring that the TC stays where IT is, will I be able to simply offer the engine back up to the box and bolt everything back up? Or are all those checks and measurements and fitments still required?
Pardon the apparently-dumb questions but I've only ever done this with manual boxes and clutches, and I'm trying to visualise the tasks involved in doing it with an auto.
Splitting them should not be an issue.
If you were doing a manual you would block the engine level sitting on the floor. Then block under the 'box in such a way that it will remain level when you slide it away. You would put it back together in the same way as you would not want to bend or stress the input shaft as you try to engage it into the splines.
I would do the auto in just the same way, The spigot on the front of the TC engages in the crank shaft in the same way a manual engages the input shaft into the spigot bearing. The difference is there is no spline and you don't need to align the TC bolts until after the bell housing is bolted up.
Steve
If you were doing a manual you would block the engine level sitting on the floor. Then block under the 'box in such a way that it will remain level when you slide it away. You would put it back together in the same way as you would not want to bend or stress the input shaft as you try to engage it into the splines.
I would do the auto in just the same way, The spigot on the front of the TC engages in the crank shaft in the same way a manual engages the input shaft into the spigot bearing. The difference is there is no spline and you don't need to align the TC bolts until after the bell housing is bolted up.
Steve
Providing the TC stays in place - I would measure just to remove any nagging doubt but there should be no need - you just put the two back together again.
As Steve_D says it's dead easy compared to a manual box & I think you're worrying that it's harder as you've not done one before. The short spigot in the middle of the front of the TC will line itself up without any need for you to do anything.
Once bolted up you just need to fit & tighten the 4 TC to plate bolts & it's job done.
There will be a bit of free fore & aft play on the TC before you fit its bolts & that's normal.
Turn the TC for the first one then the engine for the rest, I use a ring spanner (10mm?) on any of the bolts I can get at to turn the engine & go slowly.
I use a couple of beheaded bolts screwed into the back of the engine to help line the gearbox up on. (Makes refitting manual boxes easier & safer.)
Remove them after you've fitted a couple of the bolts & fit the rest of the bolts.
As Steve_D says it's dead easy compared to a manual box & I think you're worrying that it's harder as you've not done one before. The short spigot in the middle of the front of the TC will line itself up without any need for you to do anything.
Once bolted up you just need to fit & tighten the 4 TC to plate bolts & it's job done.
There will be a bit of free fore & aft play on the TC before you fit its bolts & that's normal.
Turn the TC for the first one then the engine for the rest, I use a ring spanner (10mm?) on any of the bolts I can get at to turn the engine & go slowly.
I use a couple of beheaded bolts screwed into the back of the engine to help line the gearbox up on. (Makes refitting manual boxes easier & safer.)
Remove them after you've fitted a couple of the bolts & fit the rest of the bolts.
Edited by paintman on Wednesday 29th August 08:46
Small update: Got the box and the engine split successfully, without losing the TC. However, about an hour later, in a fit of utter stupidity, I decided to check how the TC slides on the gearbox shafts so that I could check the clearance for the re-fit. One little bit of stiction and a slight tug later, and I'm holding a TC in my hands.....
Didn't drop it and no fluid lost, but I now have the enviable task of trying to feed it back onto two separate splined shafts AND get the spigots located. 15 minutes of trying didn't even scratch the surface.
A question for the uninitiated: so is all the drive transmitted via those 4 flex plate bolts? Seems bizarre to me that the only driven connection between the engine and the box is those 4 bolts on a thin sheet of steel?
Didn't drop it and no fluid lost, but I now have the enviable task of trying to feed it back onto two separate splined shafts AND get the spigots located. 15 minutes of trying didn't even scratch the surface.
A question for the uninitiated: so is all the drive transmitted via those 4 flex plate bolts? Seems bizarre to me that the only driven connection between the engine and the box is those 4 bolts on a thin sheet of steel?
Steve_D said:
Give yourself a good slapping as you were told to leave the TC alone.
Yes just the 4 bolts. You do need to inspect the flex plate carefully as they do crack. Crack starts at the bolt holes which is no surprise.
Steve
Duly administered. Is it really just a case of sitting there fiddling it until it magically drops into place?Yes just the 4 bolts. You do need to inspect the flex plate carefully as they do crack. Crack starts at the bolt holes which is no surprise.
Steve
On the bright side, I may as well replace the gearbox oil seal whilst I'm there....
CAPP0 said:
Steve_D said:
Give yourself a good slapping as you were told to leave the TC alone.
Yes just the 4 bolts. You do need to inspect the flex plate carefully as they do crack. Crack starts at the bolt holes which is no surprise.
Steve
Duly administered. Is it really just a case of sitting there fiddling it until it magically drops into place?Yes just the 4 bolts. You do need to inspect the flex plate carefully as they do crack. Crack starts at the bolt holes which is no surprise.
Steve
Yes. Fiddly because you're trying to get two sets of splines to engage & those inside the TC will settle downwards slightly due to their weight.
On my latest removal I eventually got fed up & lifted the box up with my engine crane until it was vertical - suggested in the Ashcroft link. Drained as much out of the TC as I could & fitted it.
Went on so easily I took it off & tried again - with exactly the same result. Little bit of lifting & turning the TC until it sat down indicating the cutouts had engaged which was confirmed by measurement.
Locked in place & back to horizontal for refitting to the car. The only issue with this way is that you will lose a very very small amount of fluid from the TC which will run down inside the bellhousing - providing it cleans up & doesn't keep recurring it's nothing to worry about.
Edited by paintman on Monday 8th October 14:02
paintman said:
On my latest removal I eventually got fed up & lifted the box up with my engine crane until it was vertical - suggested in the Ashcroft link.
Yes, I was thinking of that approach.paintman said:
Drained as much out of the TC as I could & fitted it.
I thought you had to fill the TC before fitting it? Mine hasn't lost any fluid (yet) but I guess turning it horizontal will drain it. How did you re-fill it?
Rotate and push rotate and push from the centre and dont let the TC hang its really not hard to get a TC to engage back in this ZF box , I just hope that when that TC fell out/slid out that the outer spline as not dragged/nicked the pump oil seal lip or you will be doing this job all over again 
bet you wish you hadn't fiddled now 
bet you wish you hadn't fiddled now CAPP0 said:
I thought you had to fill the TC before fitting it?
Mine hasn't lost any fluid (yet) but I guess turning it horizontal will drain it.
How did you re-fill it?
No.Mine hasn't lost any fluid (yet) but I guess turning it horizontal will drain it.
How did you re-fill it?
When you turn it horizontal a fair amount of fluid will come out but due to the way they're built not all of it.
It's filled by the gearbox pump.
I refilled my gearbox after refitting by pouring fluid down the dipstick tube until it registered on the dipstick. Start the engine & the pump will distribute it around the gearbox. Keep adding fluid & checking the dipstick whilst the engine is idling in 'N' until it reappears on the dipstick. Move the gear selector through all gears, pausing slightly in each before returning to 'N'. Check & top-up fluid if necessary. Turn engine off or take for test drive & re-check.
Dipstick on mine is stamped 'CHECK WHEN COLD - IDLING IN NEUTRAL'. The engine will warm up & idle smoothly but this won't affect the box fluid temp.
If the box has no dipstick but a level plug on the front of its sump the procedure is slight different.
If you're doing a gearbox service then it's an idea to measure what comes out as you will then know roughly how much you should expect to get back in. The manual says over 9 litres, but that's basically a totally empty box, cooler & TC. You're likely to get somthing just under 6 litres out.
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