Exploded view is here:
https://img486.imageshack.us/img486/7945/vvt12349we.jpgThis is the description by the manufacturer -- Delphi:
https://delphi.com/manufacturers/auto/po ... train/vcp/These are photographs of the dephaser:
https://f.foto.radikal.ru/0609/d5468e8b41b0.jpghttps://c.foto.radikal.ru/0609/4224d00a7e49.jpghttps://photofile.name/photo/romanlk/321 ... 679894.jpghttps://photofile.name/photo/romanlk/321 ... 679937.jpgThis is the faulty dephaser taken apart, old model -- P/N 7701474362.
https://photofile.ru/photo/megamike/2180 ... 436198.jpghttps://photofile.ru/photo/megamike/2180 ... 436443.jpghttps://photofile.ru/photo/megamike/2180 ... 436449.jpghttps://photofile.ru/photo/megamike/2180 ... 436445.jpghttps://photofile.ru/photo/megamike/2180 ... 437432.jpghttps://photofile.ru/photo/megamike/2180 ... 437433.jpgIt rattles as the locking pin stops doing its job. One can also see wear of the components.
This is the intermediate edition of dephaser, P/N 7701478079. The same design, metal filings discovered inside the new part...
https://photofile.name/users/south27/3500248/75608005/The third (currently the latest) reincarnation of the same part, P/N 7701478505. The same design, the pin is probably improved.
https://photofile.ru/photo/dvlion/951365 ... 095427.jpghttps://photofile.ru/photo/dvlion/951365 ... 095428.jpghttps://photofile.ru/photo/dvlion/951365 ... 095429.jpghttps://photofile.ru/photo/dvlion/951365 ... 095430.jpghttps://photofile.ru/photo/dvlion/951365 ... 095433.jpghttps://photofile.ru/photo/dvlion/951365 ... 095431.jpgThese came from this source:
https://www.renault-club.kiev.ua/forum/i ... topic=7022One of authors of this research MegaMike from the above forum discovered that the cause of the problem is excessive wear causing increased axial play (more that 0.15mm) and, as a result, oil leaking away from the dephaser back in the sump. However, the other failed dephaser had a small axial play, but the plastic flat seals were faulty... In addition, the locking pin alone appears to be unable to hold the load. It has a conical surface loaded with a side force. A projection of this force pushes the pin out of the hole. A simple calculation shows that the strength of the return spring is insufficient given a very high strength of valve springs (valve springs have to be strong to work at high revs) creating high torque on the camshaft. When a dephaser is not worn and is filled with oil this problem is not noticeable, but when it is dry then a scary rattle appears. There were 3 part numbers released, which is an indication that Renault and Delphi are well aware of the problem!
Here one can find a detailed analysis of the design fault, it is in a wrong language for most of us:
https://www.renault-club.kiev.ua/forum/i ... ntry118155To summarise, the design of conical surface of the locking pin and the return spring is not good, which includes geometry, choice of materials and the strength of the return spring. As a result the locking pin is bound to stop performing its function at some stage. It is a "joint" fault of Delphi, who supplies dephasers, and Renault, who did not test this part sufficiently well. An option is that testing was done on a prototype engine before it was enhanced by using "racing" style hard springs and cams with roller rockers.
This is an overview of dephasers:
https://www.pmgsinter.com/downloads/orlando2002_wied.pdfRenault discusses this problem in their technical note TN4432A.
This is it, I guess. The problem is down to lubrication failure and poor design by Delphi. It makes me think about possible use of special oils having extreme pressure properties, such as VW PD 505.01 (e.g. see Fuchs and Motul range at
https://www.opieoils.co.uk), or ester-based racing lubricants as a "patch" to the problem, and someone reported using Mobil 1 5w-50 oil with a great deal of success. I wonder if the recently introduced RN0700 oil specification will help to keep dephasers alive until the big service...
A funny finding: Delphi reduced weight of this part by 30-40% by using aluminium. Was it a good idea?
https://www.prnewswire.com/cgi-bin/stori ... 961&EDATE=The rumours that the latest version of dephaser includes a return valve are not true (see the photographs above). There are very minor modifications to the lock pin and the return spring.