Help! 307 1.6HDI injectors leaking for the third year in a row!

[fv43576]

I am car mechanical with 12 years experience, one of the most difficult I have ever deal with is my mum Peugeot 307 1.6 HDI 110 year 2005 estate not SW with 161,000 mile on the clock. The 1.6HDI engine design is the one of the most disaster combustion engine I have ever see than the 2.0HDI 110 because of the injectors seal. On June 2013 it start to release black carbon around the injectors neck but it does not pour oil out. I have blank the EGR because the inlet manifold was block by grease carbon which makes her engine jerk and poor MPG and it ruin the turbo because the oil lucubration to turbo was block it by carbon lump then it was fine after engine rebuild but till 2014 one of injector oil start to come out & leak on the floor, I have been replaced all four injectors seal kit include copper washer, then in 2015 start to leaking oil again when I took it out the injector No.3 and No.4 seal was very bad melt rubber has gone deteriorated probably of heated on manifold and I did replaced it again.
Since it has been fix now this is the year 2016 the oil start to coming out again. I am fed up to do it all over again, otherwise I can't tight the torque wrench setting bit more than 6nm then turn 65 degree because I have snap two bolt already where it holds the injector, I have been replace my own new bolts with wide neck.
It is not the rocker cover it has new rubber seal on it, no fumes, no compression leaking test with soap & water I can't see any bubbles come out.
Are this 1.6HDI engine have oil lucubration around the injectors ??? why ain't the rubber seal stop pouring the oil out??? I can see all other 1.6HDI on Peugeot/Citroen and Ford 1.4 same as 1.6 have same problem.
How to solved this problem, I am believe if I will tight it bit more and it will stop the leaking but I can't cos it will snap bolts again. My mum said to me if this car keeps continues have same problem she will buy same 2.0HDI 110 as she used have before because it was so reliable than 1.6.

[Oldpug]

Yes,they are crap,I`ve seen one with so much "coke" around the injectors I had to use a hammer and chisel to decoke it. All you can do is make sure the copper washers (I think I got oversize ones?) have a perfect seat. Last time I did one a Peugeot Dealer mechanic friend gave me the Peugeot special tool that cleans the head where the washer sits making it perfectly flat.

[fv43576]

I agree it is crap! I will see to do same what you said 'Peugeot special tool that cleans the head where the washer sits making it perfectly flat'.
thanks
Fab.

[wheeler]

Last time I did one a Peugeot Dealer mechanic friend gave me the Peugeot special tool that cleans the head where the washer sits making it perfectly flat.

Thats the key to doing this job. If the seat in the cylinder head is not perfectly clean & flat when you replace the washers it doesent normally take long for them to leak again.