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Discussion Starter #1
Hi all

My L322 has the ZF5HP24 is experiencing problems when engaging reverse, there is prolonged period of wait time before the reverse gear engages. Sometimes the selecting of reverse is smooth and other times is quite rough making the vehicle jolt. Hoping Phil will see this and be able to advise.

Thanks
Matt
 

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Hi Matt,

These things are difficult to diagnose when they’re inconsistent. The C clutch which (together with the F brake) engages reverse, has an accumulator/damper and a series of one-way orifice valves to ensure that engagement from stationary is smooth. The accumulator/damper lives in the lower rear valve block.



If reverse engagement always produced a jolt then this circuit might be at fault, but as it’s inconsistent it might possibly be being caused by a leak somewhere in one of the clutch circuits – especially if it were temperature dependant. I’m assuming that we can rule out low fluid level? Have you noticed if the symptoms are fluid temperature dependant? A leak might be further indicated if the engagement delay could be reduced by raising the engine revs slightly.

Phil
 

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Discussion Starter #3
Hi Phil

Thanks for the reply and sorry my response has been so slow. The engagement is slowly getting worse, although I have noticed on occasion that there is no jolt when going straight from drive at slow speed into reverse but from stationary there is almost always a jolt of some description. I have noticed that if the uptake in reverse is slow at engaging that raising the engine revs produces a much greater jolt and on occasion a bit of a bang sensation but does speed up engagement of reverse. I was under the car last weekend and there was no signs of any transmission fluid leaking from the gasket or fill/drain holes. Could you send the correct procedure to test the level of the fluid without losing too much when doing it? also are you still rebuilding transmissions in your free time as I have a feeling this issue is only going to end in one option and after the less than positive experience I have had from the company that did the last rebuild I would really only want you to do it, then I know its being done correctly this time!

Thanks
Matt
 

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Hi Matt,

The four key items when checking the transmission fluid level, in order of importance, are :

  • The vehicle must be level (horizontal)
  • The engine must be ticking over
  • The transmission fluid temperature should be close to 40°C (note that this is nearer to ‘cold’ than to ‘hot’)
  • The selector lever should be moved from P to R to N to D, and held in each position for a few seconds, before being returned to Park just before the level is checked
The fluid level is correct when a thin thread of oil is coming out of the filler/level plug hole.

If you remove the filler/level plug when the engine isn’t running you should end up with over a litre of oil down your arm (this is ZF’s punishment for not following the correct procedure).

I guess we could try a replacement valve block assembly first, but I agree that it’s looking likely that your transmission will need a rebuild.





Phil
 

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Hello, Phil.
I have a question regarding your instructions from the manual.
Do you have any idea what will happen if the transmission is in NEUTRAL instead of PARK when the level is checked and filled?

Do you think it would make any difference to the fluid level?
Thanks for your help.
 

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Hi,

No, this will have no effect on fluid level. Park and Neutral are identical hydraulically, electrically & electronically i.e. on-off solenoids MV1 & MV3 are applied, as are all the proportional pressure solenoids other than EDS 4 (for the torque converter lock-up clutch). The F brake is applied in both Park & Neutral and this is the only clutch engaged.

The reason Park is specified for setting the final fluid level is simply for safety reasons, with people working under the vehicle with the engine running, as it mechanically locks the output shaft.

Phil
 

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Thank you for your help and clarification, Phil.
Checking my fluid level, I found I was about 1 liter low.
I figure last time I changed to filter & fluid, I may have had a false full, some air that worked out over a little time maybe.

Would such a low fluid level be expected to cause any problems like Mr. Stevens had described?
I have noticed mine hesitates when put in D, then clunk into gear; more so if it has set idle for a couple days.
 

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Discussion Starter #8
Hi Phil

I have checked the fluid levels and all appears ok. Looks like it's going to need a rebuild. What I was wondering was do you still rebuild these transmission? I was thinking about buying one that is listed as faulty from eBay and having that fully serviced and rebuilt while I still can use my car, then swap mine out for the reconditioned unit. Is this something you are still doing? I did try emailing your ZF5 email address but I assume you are no longer using this any longer?

Thanks
Matt
 

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Hi Matt,

Yes, the production line is still running here :D so I’d be happy to re-manufacture a faulty transmission for you if you find one on eBay, etc. Just make sure that you get the torque converter with it. I wouldn’t spend more than £200, though. Let me know if you want a formal quotation. Sorry but I must have missed your earlier email. My old email address should still be working.

Phil
 
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