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Discussion Starter #1 (Edited)
As indicated in the title of this post, everything I am about to discuss concerns the DRY SUMP SYSTEM ONLY, i.e., 2003-2007 QPV, red head motor.

Many of you "OG" members know I have lead many discussion on the variator issue, mainly due to the fact that I, myself, had the problem. Startup rattle, eventual codes, loss of power. Over the course of 5 years, I have collected lots of interesting data from dealers, owners, techs and spoken to many people in the manufacturing industry to get a better understanding of why this is an issue and whether or not there is a way to prevent it. Finally, I believe it's solved. Please sit down and really think about what I am going to tell you. I think it's very important to everyone who either owns one of these cars or is looking to purchase one to consider what I am about to say as it, for the most part, changes the way many people believe these problems originate.

In the beginning, I purchased my 2005 with the trademark variator rattle. After researching options on getting the repair done by many dealerships and independents, I knew I was in the hole for anywhere from $5K-$10K. The only thing holding me back was not the expense, it was these questions to which I could not get legitimate answers:

1. I didn't understand why my car had failure so early in its life, when other cars had over 100K on the odo with no issues.
2. I didn't understand why the cars that failed (including mine) experienced bilateral failure. Why not just one side, if it was a bad component?
3. Why were the cars that failed so more "prone" to future failure than others? One dealer-serviced car had THREE replacements in 80K miles. Other cars had no failures throughout the car's useful life.

These things don't make any mechanical sense, assuming of course it's a failure in the hardware being replaced. An argument can be made that "both sides were installed at the same time, so they will fail at the same time," but the consistency of the "bilateral and routine" failure of all the examples I've surveyed just didn't make sense. In my mind, SOMETHING WAS CAUSING THE FAILURE OF BOTH BANKS.

So, naturally, the theories started flying. Could it be the way the driver was driving the car? That could be, as the driving habits would impact only the car being driven and have a collective impact on the variators. Could there be a pump failure or some other component in the VVT system that is accelerating the wear on the variators? That make sense too as both are fed by the same series of hydraulic components.

With that in mind, here is a very high-level breakdown of how the system operates:

In a DOHC engine, like the F136, the intake and exhaust valve timing is controlled by two camshafts with lobes that rotate on the camshaft axis pushing each valve open/closed as needed to make the engine run. The VVT system adjusts the timing of either one or both of these camshafts, in relation to the crank, resultantly adjusting the torque output based on the engine's conditions, RPM, etc. On the F430 variant, that occurs on both camshafts using one variator mounted on the front of each camshaft, exhaust and intake; on the Maserati variant, that adjustment only happens on the intake cam.

The variators are helical in design, which rotate like a screw, using engine oil as a hydraulic fluid to propel the variator in one direction or the other. This, in turn, rotates the intake camshaft, changing the timed intake/release of air and exhaust gasses in the combustion chamber, thus allocating torque when the engine needs it most. The variator is wrapped in a copper bushing beneath which there are a series of 3 sealed oil channels separated by a series of o-rings.

The advance and retard action of the variator is electronic, happening when an electrical current is sent to a hydraulic solenoid located between the camshafts. It sends a pulse of high pressure oil into the variator to trigger the advance.

The oil for the VVT system is supplied by a dedicated oil pump creating a constant supply of fluid pressure as the engine runs. There is also a variator accumulator located in the middle of the "V." This component is the SINGLE MOST MISUNDERSTOOD component of this engine and this car. This part is designed to retain consistent amount of HIGH PRESSURE to the variator system during solenoid requests and at startup.

Now for the meat of this discussion:

When deciding on how to approach this repair, I made sure I researched every part of the system so I not only understood the function of each part, but also knew what dependencies existed and how the parts could affect each other should one fail. The only hurdle I hit in my quest for knowledge was, you guessed it, the variator accumulator.

We all know what accumulators are used for and how they work in a hydraulic system. But, for some reason, few people consider this function in the Maserati when investigating variator problems. For those wondering, here is how they work:

The accumulators used in these cars are "piston" type accumulators. These are very similar to the F1 accumulators our cars use to store hydraulic fluid pressure in our F1 system. The accumulator consists of a fluid section (filled with engine oil in this case) and a gas section (filled with nitrogen), separated by a piston. The fluid section is connected to the hydraulic curcuit so the accumulator draws in fluid when the pressure increases which, in turn, compresses the gas on the other side of the piston. When the pressure drops, the compressed gas expands and forces fluid into the system stabilizing the internal pressure of the VVT system.

Most of the techs I talked to told me "they don't go bad." Or, "I've never had to replace one." However, it is well understood in the F1 community that the same device can cause huge problems in the F1 system if it is not changed at a certain interval. Why is there a maintenance requirement in the F1 system and not the engine? I'll tell you. The F1 system is not only a well-balanced system, but also is covered in pressure sensors used to detect problems using a SD scan tool. With that information, we can detect F1 pump problems, calculate pressure delivery to the slave, look at internal bleed rates and all kinds of stuff. With this access to data, we can also see when the accumulator is beginning to fail. With the VVT accumulator, we simply don't have that level of visibility. All we know is when we hear rattling, we replace the variators. Sad, isn't it?

So, do they really wear out? You bet they do. Hydac manufactures the VVT accumulators for the Maserati and Ferrari cars. According to Hydac, they are totally a maintenance item, especially when exposed to wear accelerating conditions. What are those conditions? Well, are you sitting down? Here goes:

1. When they are installed laterally, rather than vertically. THIS IS HOW THEY ARE INSTALLED IN OUR CARS. The reason is that when the device is on its side, the piston seals are always exposed to the oil in uneven distribution, thus accelerating the wear on the seals. It is the same reason why the fluid contact with the cork helps preserve wine in bottles stored on their side, as apposed to being stored upright.

2. When they are exposed to high amounts of heat. Call me crazy, but in the middle of the "V" of our V8 engines is the hottest place in the car. In fact, it's the hottest place on the planet. It certainly is hotter there than on the top of our transmission, where our well maintained F1 accumulators live!

3. When the wrong oil is used. This is the kicker! In our F1 systems, we use a specific viscosity hydraulic fluid with a bulk modulus tailored to hydraulic use. In our VVT system, however, we not only utilize an ENGINE OIL for hydraulics, but also one with a VARIABLE VISCOSITY! Don't tell me that 5W40 engine oil has the same hydraulic characteristics at high temp as Pentosin does at 100 degree lower temp! In fact, we don't even know how the stiffness of engine oil changes with the high temperatures that the location of our VVT accumulator subjects it to.

These three factors play so much of a role in the wear of these devices that HYDAC SELLS PISTON SEAL REBUILD KITS for them on a regular basis.

So, with this in mind, I needed new variators at this point, so I went ahead with the service. Jason at Enzo's did it and did a GREAT JOB by the way, sending me progress updates with pictures and addressing anything else he found that needed attention along the way. I ordered this service exactly as delivered, so please don't interpret any issues with their level of work. It was top notch. However, proceeding with this service, I elected to replace everything EXCEPT THE ACCUMULATOR just so I can either isolate and identify the issue with the problem returning, or eliminate it with the problem going away, and hold the variators and only the variators responsible for their own failure.

I suspected, that if only the variators, variator bushings, seals and all the parts were replaced, but the accumulator was to blame for their accelerated wear and failure, then the rattle should return shortly thereafter. However, if I replaced the accumulator at the same time, THERE WOULD BE NO WAY TO ISOLATE THE SOURCE OF THE PROBLEM. The fact that so many dry sump engines have a recurring problem, coupled with the information I learned about the only device I didn't replace at the time of service, prompted me to do it this way.

I replaced all the timing components at 115K miles. At 117K miles THE RATTLING RETURNED! Not only did it return, but it is behaving EXACTLY AS I EXPECTED, which is slightly different than before the replacement. Let me explain using 75% fact and 25% of my own theory to fill in the unknowns.

When the variators were disassembled, the inner lining of the copper bushings had three worn channels in them. These channels were cut into the copper by the lack of oil pressure causing the rattling. So, when they say the rattling causes no damage, well, not to the valves, but it is certainly causing wear to the bushing. The longer you wait, the deeper the channels. In fact, I find it likely that the variators may not even need replacement. Replace those bushings and viola! Sound disappears. However, what causes them to wear? If the accumulator fails to hold pressure and chambers begin to leak from one side of the piston to the other, not enough pressure will be available, at times, to power the variators properly. This is not the case during idling, however at the advance point (around 3K RPM or at startup) it makes a huge difference. This lack of pressure and lack of startup oil will cause the rattling you hear until the pressure builds up organically from the pump supplied oil, stabilizing the bushing and resuming functionality of the variator. However, with time, the rattling continues, wear to the bushing persists and even more pressure is not only lost at the accumulator, but also via the channels cut into the bushing as they grow deeper. This is when timing codes are thrown as advancement and retardation becomes limited.

With this in mind, if my 2005 QP initially had a failing VVT circuit caused by a failing variator accumulator, and only my variators, variator solenoids, bushings, seals and o-rings were replaced, then I should only have temporary relief. After which, the rattling will return, amplified by heated ambient conditions, as the variable viscosity oil will cause serious problems when heated in a faulty accumulator.

THAT'S EXACTLY WHAT HAPPENED.

Under normal conditions, the rattle is gone. However, if the timing is right (no pun), it rattles. If I start the car cold, the rattle is gone. This is because the new variator bushings are tight against the orings and the cool temps keep the pressure high in the variator. If I start the car and get it hot, shut the car off and restart. Agian, it's silent. The bulk modulus of the oil is at its weakest but the oil still exists in the top end to power the variator circuit. HOWEVER, if I run the car hot and shut it down for 2 or more hours IN THE SUN then restart, the thin oil drains from the system (normal) but the pressure that is expected of the accumulator is no longer there leaving the entire top end starved. YOU WILL GET THE LOUD RATTLE UNTIL PRESSURE IS RESTORED BY THE PUMP.

WHAT THIS MEANS

In summary, the high pressure VVT systems of the dry sump cars have a weak link. It's the accumulator. I highly recommend replacing it at 50K miles, assuming no rattling exists on startup. I am one of the few who not only has driven the car excessively to get the hands on experience to make such evaluations, but also had the opportunity to repair the car using conventional methods and pressure test the results. I have not replaced the accumulator yet, but I will very shortly. I am confident this will work. These findings are also the reason why some have installed auxiliary pumps and oil tanks and resolved the problem (on this forum). I'm not sure they realize that the variator accumulator that comes with the car is designed for the same reason and does the job well when it is working.

In closing, I hope the takeaway from this write up is knowledge about what this variator accumulator does and how much of a role it has on the integrity of the entire VVT system. I think a healthy accumulator coupled with other tips formerly discussed on this forum will greatly extend the life of the dry sump variators (one of those, for example, is minimizing load by keeping revs a bit higher than on typical cars - this is a heavy car). Also, please understand that the WET SUMP CARS HAVE COMPLETELY DIFFERENT COMPONENTS with other well-verified problems relating to the variator itself, so none of the above information applies to the WET SUMP cars.
 

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Discussion Starter #4
Thanks Erik, great explanation. Is the accumulator relatively accessible ?
Compared to the variators, yes. But, it's still a solid 3-4 hour job for someone who is experienced. The variator accumulator is located directly beneath the intake manifold, behind the alternator. The firewall forward cowlings, windshield wiper assembly, drain pan, fuel rails and intake manifold need to be completely removed to access it.
 

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Great info. Should be a sticky.
FYI: variator oil tank (accumulator) part # 190163 is about $720 at scuderia.
Question... what holds the oil in the accumulator until start up? Solenoids? Normally oil flows out of accumulators as soon as pressure drops.
Also the variator oil pump #189541 is only $107 at scuderiacarparts.com. Does this part fail? Has anyone replaced one? Has this part been ruled out?
 

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Discussion Starter #6
Great info. Should be a sticky.
FYI: variator oil tank (accumulator) part # 190163 is about $720 at scuderia.
Question... what holds the oil in the accumulator until start up? Solenoids? Normally oil flows out of accumulators as soon as pressure drops.
Also the variator oil pump #189541 is only $107 at scuderiacarparts.com. Does this part fail? Has anyone replaced one? Has this part been ruled out?
Question 1: In effect, yes. I say "in effect" because when the car is shut down, the balance of residual pressure is shared between the variator seals, the solenoids and the accumulator. When the car is restarted warm and the oil in the top end is thin, it's that pressure that should feed the variators until the adequate pressure is supplied by the pump. From an oil storage perspective, the accumulator the largest storage medium in the VVT system - if there's a leak in the accumulator, it will have the most noticeable effect.

Question 2: I do NOT believe the pump is the problem. The system stays operating due to the pump supplying constant pressure. If the pump went bad, you would see the problem at idle, not only at startup. Technically, if there were no solenoid requests, we wouldn't even need the accumulator because there would not be any sudden variations in pressure. The pump would do all the work, just as if we removed the accumulator from the F1 system and the pump continued to run. We wouldn't have a problem until we started the car or switched gears, as the solenoids, again, make requests for extra stored pressure that is not there.
 

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Discussion Starter #7
Today, I took the Maserati to the office after driving it all weekend with no noise. I arrived at about 9 and parked in the direct sun. Theoretically, the sun should keep the engine bay fairly hot and a few hours is all it should take to drain the oil out of the top end. I restarted it at noon - sure enough, it rattled very loud for about 4-5 seconds!

Under normal driving conditions, I can see where this would slip by someone noticing unless you drive and restart your car every 3 hours in the sun, repeatedly. With the new variators and parts, it only rattles under very specific conditions. This is how the problem starts. If I let it go, the bushings will get warn quickly and the rattling will appear with cooler, thicker oil as well, as in cold starts, etc.
 

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Discussion Starter #8
I am ordering a couple accumulators. One for the QP and another for the F430. The F430 unit holds a little more oil due to it's obligation to 4 variators in the F430 setup. If it fit's, I am installing the F430 unit in the QP. If it doesn't then I am replacing it with OEM part.
 

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Just thinking out loud... what prevents the oil from back flowing through the variator oil pump when its not running? Check valve somewhere? Or just the design of the pump?
 

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Just thinking out loud... what prevents the oil from back flowing through the variator oil pump when its not running? Check valve somewhere? Or just the design of the pump?
To be honest, I am not sure. However, if that was the problem, then the oil wouldn't be present for cold starts, and in the beginning stages, it is. The problem seems to originate with the system losing pressure under high temp when the engine is not running. I noticed it on other cars and by replacing everything except the accumulator, I proved this with the symptoms I am having. This past weekend, I saw another dry sump with the same variator issue - rattled loud after sitting in the hot sun.

The pressure required for startup comes from the accumulator. It can't be stored in any other place. The accumulators are known to leak with age, by design, just as our F1 units do and just as all piston accumulators do. The difference is that worn accumulator seals will leak far more under high temp and that's why these cars rattle only under certain, heated conditions in the early stages.

I also spoke to a Mercedes tech about the problems they are having with their cam phaser issues in the E350. To completely remedy the issue, they are now installing (you guessed it) an accumulator.
 

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Excellent all this my good friends. Can anyone post pictures of what these accumulators look like? Part numbers obviously too. Second-hand ones are all over ebay. $50 to $70 bux if Im looking that the right thing. That´s Cheap!
Surely it´s a luck thing with second-hand parts. But as stated above some cars go on forever. So if God and his destiny is on your side (well it wouldn't have failed in the first place if he was, but maybe some of us are here to "learn") you can walk off with one of these for sub$100 and done your "Variator Problems" are over.
Im new here Homies. 2nd owner (read: the real owner) of one of these beauties. Mines an 05 Duo Select M139 with only 15k Miles onnit man. Only had it 3 months before it just friggin failed on me. Ragging hard on a slightly inclined road the car nearly cut off and sounded ruined. Had to almost idle home. Nasty misfire now even at home in idle and the car once its back in load wont got past the mid rpm range before cutting off again.
Best regards brothers,
Winston
 

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Yeahman I think you're right Broth. Because now it won't even start man. It turns, it fires but then it turns off. I'm all ears here brother.
Winston
 

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I will not only be posting a DIY on the replacement, but also I have another 2005 donor car with the same variator problem. Here's what I plan on doing:

First, I will document the results of the replacement of my 2005 first, to verify the problem was fixed. This will show that replacing the variator accumulator either was or was not a pivotal issue in my overall variator failure;

Second, I plan on replacing only the accumulator on the donor car. If this solves the variator rattle, then we found the underlying issue with all dry sump variators. If the new accumulator does nothing for the donor car, then we will be replacing only the variator bushings next. It's a risky move, as tearing down the engine to that level is a lot of work, but it will yield good information to all the owners of the dry sump cars, if it indeed fixes the problem without replacing the variators themselves.
 

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Oh, and please, please, please don't replace any hydraulic parts with used ones. Unless it's a rigid hose or hexbolt, I won't touch ANY used mechanical parts. I've learned my lesson.
 

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Fantastic and invaluable this thread Erik my Broh! Any replies here should be just to give you thanks man. I´ll try and start a new one as to why my car won't start, or simply ask separately so as not to deviate us all here. One of the main reasons I bought one of these cars was that it was a Dry Sump one. I loved the thought of the crank spinning wildly and freely without the restriction of oil in an oil pan. And well now I have to deal with that life choice. Carry on that man!
 

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Fantastic and invaluable this thread Erik my Broh! Any replies here should be just to give you thanks man. I´ll try and start a new one as to why my car won't start, or simply ask separately so as not to deviate us all here. One of the main reasons I bought one of these cars was that it was a Dry Sump one. I loved the thought of the crank spinning wildly and freely without the restriction of oil in an oil pan. And well now I have to deal with that life choice. Carry on that man!
I agree 100%. Dry sump, single clutch, four doors. Practical? Nope. Awesome? Yup.
 

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Yeahman I think you're right Broth. Because now it won't even start man. It turns, it fires but then it turns off. I'm all ears here brother.
Winston
You've got a CEL? Get an OBD reader and check the codes, but sounds to me like something is busted inside :(

C
 
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