Hello all, I am hoping someone can shed some light on my current issue. 

My 2008 (Mk6) Fiesta 1.4 TDCi has just recently started to, well....not start lol. When I turn the key, the starter motor catches the flywheel but then seems to back off of it before the engine can fully start. I can hear the first two *chugs*, the standard diesel starting up sound, but then it just sounds like the bendix spins freely in the motor. I have already removed, cleaned and replaced the motor and had one of my friends test it whilst it was off to which he said it was okay. There is fuel and fresh oil in the vehicle and it actually runs like dream if you push start it however I do not fancy doing that every morning lol. 

If anyone has had or having the same issue then please let me know how you fixed it. The car is very important for me to get to work especially in these desperate times.

Thank you, stay safe

Arran

 

EDIT: battery has been checked

Edited November 30, 20205 yr by atlangtonxo

Might be stating the obvious, but you have checked the battery right?

6 minutes ago, Luke4efc said:

Might be stating the obvious, but you have checked the battery right?

yes lol, probably should mention that in the post

is the ring gear OK that is the teeth around the fly wheel.  you would need to remove starter motor and then turn engine slowly to check every bit of it whilst looking/ feeling in the hole. 

In the old days of inertia starters it was common for ring gears to need replacing but I think it would be very rare on modern cars with pre-engaged starter motors. 

27 minutes ago, isetta said:

is the ring gear OK that is the teeth around the fly wheel.  you would need to remove starter motor and then turn engine slowly to check every bit of it whilst looking/ feeling in the hole. 

In the old days of inertia starters it was common for ring gears to need replacing but I think it would be very rare on modern cars with pre-engaged starter motors. 

yes, we took off the motor and checked, the ring gears are absolutely fine. Flywheel looks like it's in top shape. it sounds to me like the pinion gears in the bendix aren't catching or are being pulled back prematurely by the relay

If all the external connections and earths are ok then it could be that the high load contacts within the solenoid/plunger assembly have become pitted and not allowing full current flow. If you can dissemble the solenoid then you may be able to clean them up,

It is also worth cleaning the brushes and commutator. I have had success in the past with putting packing behind the brushes and turning the copper shunts the other way round but that was in the old days when starters were much simpler and I'm not sure that you can do that with modern ones.

 

i was thinking about this further. it is a long time since i looked at a starter motor in details. does the cog on the starter have a one way clutch on it?  I think I have seen ones that do, but I am getting old and forgotten much of the knowledge I gained years ago. I am thinking the one way clutch on the cog is slipping when under heavy load.