Is your ZF Ecosplit 3 gearbox losing drive?

If you own an Ecosplit 3 gearbox and you find that it’s losing drive, follow this diagnostic approach to identifying possible causes.

As the name implies you should firstly split the unit into three very distinct modules:

1) Firstly, in the centre of the unit – and dependent upon specification – you will find the main three or four speed section.

2) To the front of the unit you will find the splitter group.

3) To the rear of the unit you can locate the range change group.

To begin, consider the following: when the unit does drop out of gear, does the gear lever itself move in the cab?  If you conduct this test and the gear lever doesn’t, in fact, move when the vehicle loses drive, it may well indicate an issue with either the splitter group, or the range change group.  In this case you need to conduct a further diagnostic in order to get to the bottom of the problem.

Steps to diagnose the fault

Firstly, find out if the splitter group will only change when the vehicle clutch system sends the relevant signal to indicate that the clutch is fully disengaged.  The system depends completely on the clutch and the manufacturer will denote which type of signal will be sent.

In contrast, the range
 group is a 
neutral signal
 system.  The range group should therefore only 
change when
the gear lever
 is in the neutral position.

If, however, the lever does continue to move when the gearbox loses drive, it strongly suggests it’s the main three or four speed section that might be the issue.

As a follow up diagnostic, check whether that happens across all the gears.  if the lever only moves when in one or two particular  gears, it usually means there’s an issue with the relevant synchro, which can be reproduced in both high and low range, this being:

16 speed: 1st/5th, 2nd/6th, 3rd/7th, 4th/8th

12 speed: 1st/4th, 2nd/5th, 3rd/6th

Unfortunately for you and your wallet, this will necessitate specialist investigation to rectify, so you should contact the appropriate engineer.

Possible problems with your ZF gearbox

If the lever actually moves in all the gears when you run this test, it suggests you might have a problem with one of the following:

1) Linkage incorrectly adjusted or worn

Ecosplit linkageTry removing the linkage.  Then conduct the following driving test off any main roads, in a safe driving environment: Drive the 
van in the
 low gear with which you had the problem. If it doesn’t stop the problem with the gears dropping, then you’re almost certainly looking at a gearbox issue.  Conversely, if it does, then you’ll know the issue was indeed to do with the linkage.

2) In gear detent worn

in gear detentThe gear detent helps with holding in the gear that has been selected.
 You’ll usually find it on the shift turret, depending on the model of the vehicle you’re driving.  Remove the item and check for wear and tear.


3)Wear at the shift turret

shift turret ecosplit 3This, we’re afraid, is not good news.  In fact, wear at the shift turret may well be an indicator that other gearbox parts also need replacing.  If you do find wear at the 
shift turret, it’s also something that will require specialist 
investigation and mechanical expertise so in these instances you will need to get the van to a professional mechanic or engineer.

Further considerations and Ecosplit gearbox tests

Try to obtain drive simply by depressing the clutch.  If you are able to put the vehicle into drive in this way, then certainly the splitter group is at fault.  You can then at least narrow your search by trying these three ideas:

  • Check the detent.  You’ll find it located at the bottom within the webbing, at the front of the main case and you’ll know you’ve found it, because oil will come out if it’s removed. See if it’s worn.
  • Try removing the air supplies to the gearbox.  Do the gears still drop out?
  • Check and confirm that the valves are indeed receiving the relevant air supplies.  That could be the issue.

If you check these three things and find that they are all fine, then in all probability the splitter synchro is worn.  Again, this will require further, and specialist, investigation from a fully trained engineer.

Conversely, if you find you have to move the gears into neutral to obtain drive, then you can be assured your problem lies with the range change group.  You can further narrow the search by checking through these points:

  • The detent is located just behind the range change cylinder, at the top of the rear housing.  Is it worn?
  • Does the gearbox still drop out if you remove the air supplies?
  • Again, check and confirm that the valves are indeed receiving the relevant air supplies.

If these three checks come back fine, then the trail leads to a worn down range change synchro. Again, this requires the specialist TLC of a qualified mechanics or engineers.

Ecodrive are ZF specialists. For more repair advice on this, or any other ZF product contact a member of the Ecodrive Technical team on 01204 701 812.