Quattroporte Rattle on Start Up

[daverichardson]

Sorry for delay in replying - internet gremlins now sorted
Wet sump is the answer
d

 

[Michael]

Thanks Dave - what mileage had it done at the time of the work pls?

 

[daverichardson]

Hi Michael
I believe it was done at JCT 600 in Leeds at 45000 miles approx.
hope this helps??
d

 

[Michael]

Thanks Dave it does - how old was your car when the work was done? Do you know if it was under warranty or did the PO pay pls? Thx. Michael

 

[daverichardson]

Let me see,
It is a 2007 model, the work was done under warranty not sure when the work was done
I think it was 2013 since I bought it in Feb 2014 just after the 50000 mile service etc
d

 

[Michael]

Thanks

 

[jcoyne]

Is this the reason for the rattle on start up ?

I posted this on the maseratiforum a while ago, not sure if it helps

I've just been looking through the collection of the Maserati Academy documents that have just been posted here here One document (the 4200 wet sump engine overhaul training manual) explains how the cam variator is held in place (at rest) by a spring loaded locking pin. here and full document here http://www.scribd.com/doc/201140054/4200-Wet-Sump-Engine-Overhaul (what look like notes from the training course) explains that a rattle on start up can be caused by the pin not engaging https://www.dropbox.com/s/jf640pxmcfrorr5/Dec-11-2014_11.51.47-CapturFiles.png?dl=0 So I guess the explanation on the wet sump (QP & GT autos) is that the spring forcing the locking pin into the cam variator at rest, gets gradually weaker over time and does not always lock the variator into place properly. Then when the engine is started you get the rattle because the variator can move as there is neither the locking pin, nor oil pressure to hold its position. This may explain why the rattle does not start until the cars are 3-4 years old, and why its intermittent as the spring weakens. IF thats correct, then the fix is a new spring - but getting to it is another story!

Has anyone had the noisy cam variators fixed at any of the Independants?

What sort of money/time has it taken? Best Regards, Jason

 

[jcoyne]

My 4.2 Automatic QP has 88K on the Clock and has rattled on startup about 1 morning in 3 since 56,000K - I think its the pin that holds the variator in place at rest that has a weak spring - I'll post my reasoning later.

I'm no expert but my Opinion is that its no problem as the engine speed is so low on start up and the oil is there in 1-2 seconds.

 

[safrane]

Friend had his coupe done at Emblem in Poole just the valve replaced £400 inc VAT.

 

[jcoyne]

Hi Safrane,

I've heard people talk of the valve - but what valve is it ?

I'd always thought that it only rattled on the 4.2 automatic QP & GT's, from mid 2007 until were replaced by the 4.7

 

[Michael]

Hi Safrane,

I've heard people talk of the valve - but what valve is it ?

I'd always thought that it only rattled on the 4.2 automatic QP & GT's, from mid 2007 until were replaced by the 4.7

Thanks Safrane - I'll contact Emblem. Thanks jcoyne - as I'll ask about the spring too. I appreciate that it probably doesn't do the car any harm and there are many high mileage 4.2 engines out there to prove it - but if I can get if fixed that price then I think I will.

 

[rs48635]

So is this rattle at startup confied to wet sump engines?
Seems to be specifically mentioned in the course manual.

Other items of interest;
80% of components differ from the Dry to wet Sump

 

[Michael]

Hi - rs

Yes - confirmed as a wet sump issue on the 4.2 only.

regards

 

[QP4Me]

Mine is 2005 QP 4.2 dry sump, with about 60,000 miles on it. About 1/3 of the time it 'rattles' for about 1-2 seconds when starting from cold. While its not enough time to do any damage, I do start from cold in a certain way. I let the engine turn over a few times, switching off just before it starts, then I turn over again and let it fire. No problem! I have learned to not let it hurt my sensitive ears!

 

[CatmanV2]

I'm not sure that process is going to do anything any good at all, but prepared to be corrected.

C

 

[QP4Me]

I believe it does, as it pressurises the engine and pumps oil up to the head. There is no rattle after i start in this manner.

It could very well just be based in a human/car psychosomatic type of disorder, but the placebo effect makes a real effect on my bank balance.

 

[CatmanV2]

I was more concerned about what it's doing to the bores, dropping unburned petrol in, similarly the cats and what the ECU 'thinks' about it.

C

 

[QP4Me]

Good point. The 'normal' starting procudure involves several turns of the motor without firing, so I would imagine petrol is only introduced after a pre-determined number of 'unfired' turns?

In fact, what is the point of the 'unfired turns' in the first place?

 

[CatmanV2]

There's no 'point'. Fuel needs to get in to the cylinders at the right ratio, temperatures need to raise, sparks need to fly, things need to get up to speed (literally). I suspect the odds of one of your cylinders being right at correct point for the start of a cycle when you stop is just about nil (although the more cylinders you have the greater that chance will be). Even if there *is* it'll be stationary and the ECU will be trying to compensate for slower speeds.

I've never seen *any* engine that does not turn over 'a bit'. Single cylinder two strokes were closest, which make sense.

Having said all of that, I have no evidence that this will do lasting harm, but I wouldn't be in the least surprised. Manuals have a specific starting instructions

C

 

[QP4Me]

No other motor I have has this built-in delay, including straight and v8's, maybe its purely cosmetic.