Grand Scenic 1.6 sammuu kylmänä

Kylmäkäynnistyksessä kuuluu parin sekunnin ajan naputus moottorista. Lienee sama vika. Velipojalla Megane samalla moottorilla ja sama vika. Autosalpassa olivat selitelleet, että johtuu nappikäynnistyksestä. Tuo vvt-yksin korjaus kuulostaa pahalta. Auto GS 1.6 vm 2005 ja ajettu 35 tkm. Rellusta voinee sanoa, että auto hyvä mutta tehty huonoista ja kalliista osista...kele!

Delphin valmistama osa viallinen. Kts viesti (megane II ownersforumista lainattu, vaati rekisteröitymisen)

http://www.meganeownersclub.co.uk/forum/viewtopic.php?f=2&t=8033&p=53990&sid=97ce93cdc990a5edc39ca179179ec320

Exploded view is here:
http://www.renaultbiler.no/forum/showim ... pulley.jpg
http://img486.imageshack.us/img486/7945/vvt12349we.jpg

This is the description by the manufacturer -- Delphi:
http://delphi.com/manufacturers/auto/po ... train/vcp/

These are photographs of the dephaser:
http://f.foto.radikal.ru/0609/d5468e8b41b0.jpg
http://c.foto.radikal.ru/0609/4224d00a7e49.jpg
http://photofile.name/photo/romanlk/321 ... 679894.jpg
http://photofile.name/photo/romanlk/321 ... 679937.jpg

This is the faulty dephaser taken apart.
http://photofile.ru/photo/megamike/2180 ... 436198.jpg
http://photofile.ru/photo/megamike/2180 ... 436443.jpg
http://photofile.ru/photo/megamike/2180 ... 436449.jpg
http://photofile.ru/photo/megamike/2180 ... 436445.jpg
http://photofile.ru/photo/megamike/2180 ... 437432.jpg
http://photofile.ru/photo/megamike/2180 ... 437433.jpg
It rattles as the locking pin stops doing its job. One can also see wear of the components.

This is the intermediate edition of dephaser -- no return valves here:
http://photofile.name/users/south27/3500248/75608005/

These come from this source:
http://www.renault-club.kiev.ua/forum/i ... topic=7022

One 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. MegaMike is convinced that this mechanism can be easily repaired by machining the parts and making the spring stronger. It is probably pointless now, as a new dephaser unit is in production since 2006 or 2007. In fact, there were several 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:
http://www.renault-club.kiev.ua/forum/i ... ntry118155
To 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:
http://www.pmgsinter.com/downloads/orlando2002_wied.pdf

Renault 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 http://www.opieoils.co.uk), or ester-based racing lubricants (e.g. Motul 300V, Silkolene Pro, Redline) as a "patch" to the problem, and someone reported using Mobil 1 5w-50 oil with a great deal of success.

A funny bit of information: Delphi also reduced weight of this part by 30% by using aluminium. Was it a good idea?
http://www.prnewswire.com/cgi-bin/stori ... 961&EDATE=

The latest version of dephaser includes an additional valve, which stops oil from escaping. This is by rumours only -- the intermediate model was very similar to the first one. There is no data so far about any modifications to the lock pin and the return spring.

Meillä oli se letku murtunut. Sammuili kylmänä ja oikealle kääntäessä. Koneen lämmetessä kaikki ok.

Tämä on jo vanha viestiketju, mutta unohdin kertoa mikä se lopullinen vika sitten oli. Eli noin 5-6 Auto-Salpassa vietetyn huoltokerran ja kaikkien mahdollisten osien vaihdon jälkeen (jakohihna, vvt-pyörä jne.) syypääksi osoittautui viallinen solenoidi. Sen jälkeen on 40 000km mennyt ilman suurempia ongelmia. Autohan oli Grand Scenic 1.6

Nyt kun auto täyttää 5 vuotta niin se on vaihtumassa uuteen Grand Sceniciin.