Technical 1996 fiat ducato 2.5td gearbox seal failed after only 1500 miles!

[MrkT]

one of my recently replaced gearbox seals has failed after only 1500 miles!
i have replaced both seals and new shafts at the same time.
Traveled to Manchester yesterday and after a 3hr drive pulled up and a few minutes later noticed gearbox oil badly dripping out from the left seal.
i have changed the gearbox oil around 3 times in the last year,and always overfilled to 3.25ltrs to protect fifth gear.(manufacturer states 2.75ltrs which is too little)
Before i replace the seal again......anybody have any idea why it may have failed??
also,when installing,just to be sure,should the seal fit flush with the outer gearbox lip or driven in as far as it will go??
thanks in advance.

 

[Bonefish Blues]

I thought overfilling gear oil was bad, creating problems including, but not limited to putting extra pressure on gearbox seals? Serious observation, based on ignorance of this unit, but an extra half litre seems a lot to me?

 

[MrkT]

I thought overfilling gear oil was bad, creating problems including, but not limited to putting extra pressure on gearbox seals? Serious observation, based on ignorance of this unit, but an extra half litre seems a lot to me?

yes normally i would agree,however it is a well known fact that these gearboxes (especially 5th gear which is splash lubricated) does not get enough oil feed at 2.75ltrs and subsequently fails. 1/2 a ltr more is about right apparently. so it gets filled to 3.25ltrs as recommended elsewhere.
however,i think I've found out why its failed now,and you are right in some ways. when filling we were using a 1/2 ltr jug.......it takes about 10-15mins per half litre to drain into the gearbox through a tube and funnel into the reverse light switch hole........i think we may have lost count when filling,as i have just drained the gearbox oil and despite the fact we have lost some, I've just drained down just under 3.25ltrs!! (and we had lost what looked like a quarter ltr and driven 3 hrs home with a leak!) Thankfully its just the seal that has gone and a valuable lesson learnt! next time we shall measure it out first and then pour it in!

 

[Bonefish Blues]

yes normally i would agree,however it is a well known fact that these gearboxes (especially 5th gear which is splash lubricated) does not get enough oil feed at 2.75ltrs and subsequently fails. 1/2 a ltr more is about right apparently. so it gets filled to 3.25ltrs as recommended elsewhere.
however,i think I've found out why its failed now,and you are right in some ways. when filling we were using a 1/2 ltr jug.......it takes about 10-15mins per half litre to drain into the gearbox through a tube and funnel into the reverse light switch hole........i think we may have lost count when filling,as i have just drained the gearbox oil and despite the fact we have lost some, I've just drained down just under 3.25ltrs!! (and we had lost what looked like a quarter ltr and driven 3 hrs home with a leak!) Thankfully its just the seal that has gone and a valuable lesson learnt! next time we shall measure it out first and then pour it in!

 

[Communicator]

yes normally i would agree,however it is a well known fact that these gearboxes (especially 5th gear which is splash lubricated) does not get enough oil feed at 2.75ltrs and subsequently fails. 1/2 a ltr more is about right apparently. so it gets filled to 3.25ltrs as recommended elsewhere.
however,i think I've found out why its failed now,and you are right in some ways. when filling we were using a 1/2 ltr jug.......it takes about 10-15mins per half litre to drain into the gearbox through a tube and funnel into the reverse light switch hole........i think we may have lost count when filling,as i have just drained the gearbox oil and despite the fact we have lost some, I've just drained down just under 3.25ltrs!! (and we had lost what looked like a quarter ltr and driven 3 hrs home with a leak!) Thankfully its just the seal that has gone and a valuable lesson learnt! next time we shall measure it out first and then pour it in!

The MLGU box on my x244 2.8jtd has a similar capacity and splash lubrication for fifth gear. I have never read of filling with more than 3.0 litres. The advice that I try to follow regarding fifth gear, is not to use it for the first mile, if the vehicle has been standing for longer than overnight.

 

[MrkT]

The MLGU box on my x244 2.8jtd has a similar capacity and splash lubrication for fifth gear. I have never read of filling with more than 3.0 litres. The advice that I try to follow regarding fifth gear, is not to use it for the first mile, if the vehicle has been standing for longer than overnight.

to be honest the internet is full of advice (wrong or right) some say 3ltrs,some say 3.25 litres. i have just had a re-read of some of these,and a gearbox specialist who has just rebuilt someones reckons to fill to 3.25ltrs. i suppose anything a little over 2.75ltrs (3 ltrs-3.25 litres max) should be good.
i reckon we may have mistakenly put 4 litres in.......which is not so good!
The trick with these gearboxes I've read on numerous forums,is overfill slightly as above, don't use 5th until engine is fully warmed,and don't change into 5th until over 50mph.
That's what i do anyway. oh,and don't overfill!!