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ZF 5HP24 teardown
- Thread starter Bemble
- Start date
I had a guy drop off a 5HP24 with me just before Christmas because his '05 Range Rover wouldn't engage reverse – otherwise it worked normally. He'd been managing with it like this for some while and said that he'd got used to being very careful when choosing a parking space!
Although the 'classic' cause of this in early 5HP24s was the deterioration of the bonded F-brake piston seal (this applied to BMWs & Jaguars from the late 90's) I'd never seen this problem with an L322 transmission so I assumed ZF had fixed it. Anyway once I had the transmission stripped I could see that the F-brake piston was, in fact, fine.
In reverse both the C-clutch and F-brake are engaged and I then found what was causing the problem. The C-clutch was failing to engage because of leakage in its hydraulic feed line due to two failed static O-Ring seals on the support bush. These seals are included in the overhaul kit so it will be a simple & relatively cheap repair.
Although the 'classic' cause of this in early 5HP24s was the deterioration of the bonded F-brake piston seal (this applied to BMWs & Jaguars from the late 90's) I'd never seen this problem with an L322 transmission so I assumed ZF had fixed it. Anyway once I had the transmission stripped I could see that the F-brake piston was, in fact, fine.
In reverse both the C-clutch and F-brake are engaged and I then found what was causing the problem. The C-clutch was failing to engage because of leakage in its hydraulic feed line due to two failed static O-Ring seals on the support bush. These seals are included in the overhaul kit so it will be a simple & relatively cheap repair.
Hiya- seems mine has just gone too
Is there anyway I could email you?
I've found a few cases where people have replaced/recon gearbox and no difference
How would one determine the actual problem?
I had my gearbox oil and filter changed about 4-5000miles ago....and had a few very heavy clonks/bangs....only got Reverse and 4/5 gear
Is there anyway I could email you?
I've found a few cases where people have replaced/recon gearbox and no difference
How would one determine the actual problem?
I had my gearbox oil and filter changed about 4-5000miles ago....and had a few very heavy clonks/bangs....only got Reverse and 4/5 gear
"Is there anyway I could email you?" - I'll send you a PM
"I've found a few cases where people have replaced/recon gearbox and no difference" - probably because it was the transfer box shift motor potentiometer causing the issue
"How would one determine the actual problem?" - you could get the DTCs read using Testbook/T4. Note, however, that Autologic (diagnostic kit used by independent workshops) doesn't appear to be able to diagnose the potentiometer issue
"I've found a few cases where people have replaced/recon gearbox and no difference" - probably because it was the transfer box shift motor potentiometer causing the issue
"How would one determine the actual problem?" - you could get the DTCs read using Testbook/T4. Note, however, that Autologic (diagnostic kit used by independent workshops) doesn't appear to be able to diagnose the potentiometer issue
Hello Bemble, you seem to be the expert around here. I own a 99' Jaguar XJ8 which has also has got the ZF5HP24 transmission, and I've encountered the same exact problem as 1610rash. As you recommended I removed the pump flow regulator valve, and it looks just like the one you posted pictures of. However, i went ahead and measured the spring, and the free length turned out to be 81mm. Do you have any ideas as what could be wrong?
That's a very accurate discription of the symptomes. Usually the transmission feels smoother when cold. When the car is stationary and you put it into`D´or `R´ it feels a bit more gentle. I.e it gets worse after the transmission has reached it's operational temperature.
If I put it into either `D´or `R´ while stationary and then release the brakes it starts to move slowly in the reverse or forward direction. However, if I apply the gas to harsh (very gentle), it revs up 350rpm or so and then slams into gear with a bang. I have learned to drive in a way to avoid this from happening, my technique is to apply the accelerator with absolute care.
Before you ask, I did change the oil and filter about a week ago, but the problem still persists. I have also disconnected the battery to reset the system. Indeed it did, it took about 10 minutes of driving to get it to shift perfectly at higher gears again.
I have never had any fault-messages anouncing on the dash. However my Jag-friend in Sweden have offered me to read the hidden fault codes with a OBD-reader.
It's usually straight–forward to pin faults like this down to a particular clutch but, because your problem occurs in both forwards and reverse which use completely different clutches, it doesn't sound like a clutch problem to me. There's clearly a lack of flow at idle which means either there's a problem with the pump or that you have a leak in the hydraulics somewhere because the pump flow at idle isn't sufficient to maintain pressure. Increasing fluid temperature reduces the fluid viscosity causing more fluid to leak and the problem to get worse. In either case, in my view, your transmission will have to come out for repair.
bofabill
Accelerating Away
I read on here somewhere that ye can reset the gearbox 'brains'
maybe worth a try as it costs nothing to do.
press accelerator to floor and hold it ther
put key in ign and turn to position II
(all dash lights up )
leave for one min
ignition off
key oot
pedal up.
this apparently clears driving habbits and eventuly changes to your habbits (good or bad
)
maybe worth a try as it costs nothing to do.
press accelerator to floor and hold it ther
put key in ign and turn to position II
(all dash lights up )
leave for one min
ignition off
key oot
pedal up.
this apparently clears driving habbits and eventuly changes to your habbits (good or bad
)It sounds very likely to be a pressure related problem that I have with my transmission. However, I doubt it is the pump that is worn out, because when i changed the oil and filter (filter dated 1997) there was not very much metalsludge collected on the magnets, I even dissected the filter, just to find very little evidence of wear.
Pumps usually don't go bad without a cause? An overheating gearbox, or even more likely a low oil level (I got ~6L out and ~6L in). None of which I belived to have occured.
I also have a whining sound from the transmission when it's cold and I accelerate hard. It's also clicking while idle if cold.
I belive it might be a problem with the valvehousing after reading this (warning BMW-forum): http://www.bimmerboard.com/forums/posts/615187
Or perhaps the Main regulator valve?: http://www.youtube.com/watch?v=Az0e1fjtFQQ
Maybe a valvebody swap will solve my problems? I really don't wanna remove the transmission, did that last summer on my XJ40 with the 4HP24. It was a nightmare.
Last edited by a moderator:
Well I don't think it is your valve block, and they're pretty expensive to replace, but there's certainly no harm in you stripping yours down to check. They're very easy and straightforward to do and don't require any special tools beyond a Torx T27 driver. You'd just need to buy a new gasket (a few quid).
Thank you very much Bemble for those pictures, and thank you bofabill for the reset advice! The reset did not do any difference, although it was a good idea to try.
Today i removed the valvebody from the transmission. I think I might have discovered the fault! After a breif inspection of the valvebody I found a ~5cm crack. The crack is located in the exact same area as documented on the BMW forum.
Compare this BMW 5HP24; (http://www.bimmerboard.com/forums/posts/615187) with my Jaguar 5HP24;
Perhaps it's possible to weld the crack? Any advice?
The reset did not do any difference, although it was a good idea to try.Today i removed the valvebody from the transmission. I think I might have discovered the fault! After a breif inspection of the valvebody I found a ~5cm crack. The crack is located in the exact same area as documented on the BMW forum.
Compare this BMW 5HP24; (http://www.bimmerboard.com/forums/posts/615187) with my Jaguar 5HP24;
Perhaps it's possible to weld the crack? Any advice?
Wow...... Fortunately they fixed that issue by the time the L322 was launched. You can see two indentations in each block where they test its strength/hardness at exactly that position before passing it off.
If you're stuck I have some spare upper valve blocks knocking about (without cracks in!)
. Fortunately they fixed that issue by the time the L322 was launched. You can see two indentations in each block where they test its strength/hardness at exactly that position before passing it off.If you're stuck I have some spare upper valve blocks knocking about (without cracks in!)
Wow.....
If you're stuck I have some spare upper valve blocks knocking about (without cracks in!)
Wow, well I guess the it's likely the crack that is causing my problems then. Good news since it's an easy part to replace! How much do you want for that upper valveblock?