Independent Renault Forums banner
1 - 20 of 31 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
Hi all

My dad has a Grand Scenic. It has only done 30k and is making the most horrible noise on startup.

He has just had oil changed and it is still the same. He is wondering if anyone can help him with what it may be and how much it costs to fix? I assume it may be a common problem? See vid below:


Thanks in advance for any help guys
 
G

·
I'd say the dephaser is broken. Common on the 1.6 VVT engine.

You're looking at getting the cambelt done too while the dephaser is being replaced.

Depending on age, Renault may help with costs here, but you need to ask first, not after the work is done.
 
G

·
I think the dephaser is a Renault only part, so you can't get it cheaper elsewhere. It's about £160.

I paid £324 for a belt change at an independant, not including the water pump as that was deemed to be fine.

So, as noel says, it's going to be around £500.

The dephaser can be hobbled, so the rattle is silenced by the internal bits being fixed in place, there are threads on here about this. You still need to get it off to do that, so not really a cost saver unless you can do all that yourself and it's debatable whether it is a good thing to do.
 
G

·
The dephaser can be hobbled, so the rattle is silenced by the internal bits being fixed in place, there are threads on here about this. You still need to get it off to do that, so not really a cost saver unless you can do all that yourself and it's debatable whether it is a good thing to do.
The 1.6 dephaser pulley isn't the same design as the F4R & F4P dephaser pulleys. The 1.6 ones I've seen have 4 large chambers unlike the larger engines which have 8 chambers which makes them easier to do
 
G

·
I didn't know that RS, but I question the whole idea of messing with the dephaser. These cars don't even like the wind in the wrong direction, let alone having part of the engine hobbled.:d
 
G

·
I didn't know that RS, but I question the whole idea of messing with the dephaser. These cars don't even like the wind in the wrong direction, let alone having part of the engine hobbled.:d
Not all engines have VVT so based on this I make the assumption rightly or wrongly that it's of no detriment to an engine not to have it.

In the photos a 1.4 K4J / 1.6 K4M cylinder head form a 2003 1.4 Scenic and a 2.0 F4R cylinder head circa 1999 I belive. They both use exactly the same pulleys having the same part number. The 2.0 cylinder head is only very slightly wider and longer than the 1.4





I have a 1.4 Scenic as a run and it's pretty gutless, you have to keep the revs up and use the gearbox to keep it moving at a reasonable rate of knots so I wonder why VVT isn't used on the smaller engine which would benefit from a bit more oomph? :confused:

From what I read even after having a dephaser changed they can still eventually start to rattle again and IMO the benefit of it isn't noticable then why bother spending money on new dephaser ?

Though my experince is limited to the MK1 Phase 2 Scenic. Maybe on the MK2 Scenic like yours it is of greater benefit ?

I have recently bought another dead Scenic a 2001 2.0 Monaco on removing the engine cover I found the dephaser pulley was missing and the end of the inlet camshaft snapped off! :eek: I wonder if the cause of this was a badly rattling dephaser pulley?

In the photo the broken inlet cam shaft and at the side of it a non VVT 2.0 inlet cam shaft which has only 2 cross holes through it. The broken cam shaft would have been 6mm longer and have extra oil grooves in it which might mean it's not as strong?

 
G

·
Though my experince is limited to the MK1 Phase 2 Scenic. Maybe on the MK2 Scenic like yours it is of greater benefit ?
I wouldn't say that. I don't notice any oomph at all, in fact I'd say it was less oomphy than my old Scenic F4R.:d That had VVT too, but I didn't know it until I heard about VVT and decided to check. There it was, the dephaser solenoid on the cylinder head.

From what I've read it's no great technical advancement. It's not a gradual increase in valve overlap, rather a switch from one position to another at around the 1400rpm mark. Not exactly variable and kicks in barely above idle.Apparently...
 

·
Premium Member
Joined
·
24,215 Posts
You have to consider on VVTi engines that not only will the valve timing alter but also at the same time when the throttle is opened the ignition timing will also change.
I suspect the ECU mapping would be different on the VVTi engine. In other words the ignition timing advance or retard sequence may be different.
 
G

·
You have to consider on VVTi engines that not only will the valve timing alter but also at the same time when the throttle is opened the ignition timing will also change.
I suspect the ECU mapping would be different on the VVTi engine. In other words the ignition timing advance or retard sequence may be different.
Hmm, is it possible for mapping to be corrupt? I'm just guessing, but in my ongoing fight to get my car running smoothly, I'll consider all options.
Assuming the mechanical advance is working, how would I know if the ignition timing sequence was matching it?
Would an ECU reset override it?
Would it show up any codes at diagnostics?
The car idles fine, starts fine, revs fine at standstill, it just runs bad.:confused:
 

·
Premium Member
Joined
·
24,215 Posts
I'm not suggesting the mapping is corrupt just that the mapping for the VVTi engine may be different to that of the non-VVTi variety.
If that was the case and the dephaser was removed then the mapping may not be compatible.
As the ignition timing is influenced by the map sensor particularly when the engine is under load I would think the mapping would need to be different on engines where the valve timing can be altered.
 
G

·
I didn't think that you suggesting that, but it made me think that if the mapping was not correct, for whatever reason, it could explain why all the mechanics that have looked at my car just scratch their heads, saying that no faults come up so it must be alright.

Regards the MAP sensor, I disconnected it the other day and the car went like a rocket, but still had slight hesitation as before. The cabin resonated more than usual too, on idle.

Still, proved that there is some power there somewhere.:d

I understand that MAP sensors have specific values that can be tested and measured to determine correct operation of the sensor.
No luck googling this though?
 
G

·
With VVT the inlet valve timing gets advanced so the valves open sooner than they would with static valve timing when the engine is set to TDC.

If the valves are opening sooner then I would have thought the injectors have to open sooner too, to deliver fuel sooner ? Otherwise whats the point of the valves opening earlier if no fuel is entering the cylinders?
I see, but what makes the injector fire? How does it know the valve is open?
 
G

·
WTF? The last few posts on this thread have gone. Whats happened?

Mr Lagdti has intervened trying to de-confuse things :)




I see, but what makes the injector fire? How does it know the valve is open?

The injectors don't fire they just deliver fuel on the induction stroke. The spark plugs ignite the mixture on the compression stroke. with static valve timing then the injectors will always open at the same time which is one of the functions of the TDC sensor I would imagine.
 
G

·
So, the fuel is drawn into the chamber by the vacuum?

Before that, is the fuel pumped to the injector rail and the pressure regulator makes sure it doesn't over supply it?
 
1 - 20 of 31 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top