Pop top self correction

[ColinLBlr]

Hi
We have a Nov 2022 VW cali ocean 4 motion. Since we bought it we noticed the roof sagging. Following lots of threads we measured the drop over 24 hours as 20mm both sides. We thought the self correction only was on earlier models as ours never kicked in. Suddenly last night we were wakened with the roof self correcting, this happened at 4am then repeated at 7am. This morning it happened again at midday. Question is why it’s suddenly happening. We did a van software update a few days ago? Any thoughts welcome.

 

[RockinNRollin]

I have a feeling the first 24 hours or something it doesn't self correct, then after that it does? Maybe it's just not sagged enough for long enough before?

FWIW mine sags a bit after a few days in hotter weather and it hasn't yet autocorrected itself (at all).

 

[ColinLBlr]

We have had the van from new and in hot weather it always sagged. This year we decided to measure the sag over 24 hours as it was happening every day. We have tried lowering/ raising 5 times but only marginal if any improvement. But the change now is we have never had it automatically correct itself, now every 5 hours it is happening. That’s 4 times today already. No idea why it’s suddenly started the drop is no worse than before?

 

[dspuk]

Afraid to say this has to be a dealer warranty issue which means you need all the luck you can get.

 

[TripleBee]

I have never experienced any self correction in the 15 years of ownership, and sometimes a week without moving the van.
Every 2 - 3 days I have to correct myself.
I guess they all have a mind of their own, and just like with women, you can never get a hold on it.

 

[CaliforniaCylus]

The manual states a check happens at 10 hours and then every 5 hours. Once a check shows no need for inflation, no more checks are done.

Ours does this precisely, but I've a feeling that messing with the ignition or manually adjusting the roof interferes with this timer.

The drop has to be 200mm over 72 hours for the issue to be addressed.

 

[KevH]

Hi
We have a Nov 2022 VW cali ocean 4 motion. Since we bought it we noticed the roof sagging. Following lots of threads we measured the drop over 24 hours as 20mm both sides. We thought the self correction only was on earlier models as ours never kicked in. Suddenly last night we were wakened with the roof self correcting, this happened at 4am then repeated at 7am. This morning it happened again at midday. Question is why it’s suddenly happening. We did a van software update a few days ago? Any thoughts welcome.

Do you mean 20mm or 20cm?
The official VW tolerance is the latter, so at 20mm you don’t have a hope of a warranty claim it seems.
BTW which software update did you obtain?

 

[Benham]

The manual states a check happens at 10 hours and then every 5 hours. Once a check shows no need for inflation, no more checks are done.

Ours does this precisely, but I've a feeling that messing with the ignition or manually adjusting the roof interferes with this timer.

The drop has to be 200mm over 72 hours for the issue to be addressed.

Just before I go to bed I drop my roof slightly, then raise it to full height. That way if the vehicles checks after 10 hours, then I’ve had a good night’s sleep. I do this every night when the roof is showing a tendency to drop. My Cali has been to the dealer half a dozen times to “fix” the issue, but without success. It’s regretfully something that I have having to live with.

 

[andyinluton]

Afraid to say this has to be a dealer warranty issue which means you need all the luck you can get.

Why is it a warranty issue? the self correction is working exactly as described in the handbook.

 

[ColinLBlr]

Do you mean 20mm or 20cm?
The official VW tolerance is the latter, so at 20mm you don’t have a hope of a warranty claim it seems.
BTW which software update did you obtain?

From where I measure inside it’s 20mm. Is there a spec for the measurement ie where it’s taken 20 cm is a huge drop picture shows how flappy ours is after 5 hours.
Not sure what the s/w ref no. Is I’ll check once we move as camped just now.

View attachment IMG_5413.jpeg

 

[dspuk]

Why is it a warranty issue? the self correction is working exactly as described in the handbook.

I guess it depends if the OP means 20mm or 20cm. If it's the latter, even if in "VW Tollerance" I'd be hunting for a fix. Luckily ours has never done it apart from once in raging heat.

IMHO, and industry warranty experience, the handbook addition/modification is more of a we'll mark this flaw as expected behaviour and chuck a software fix in rather than replace everyones/some rams/pumps because some of our batch tolerances were not very good.

Happy to be schooled though - my understanding is there are two main reasons it happens - a heat related viscosity challenge, where the software self correction makes sense, or poor seals (due to various reasons) on the pumps, meaning over time the fluid leaks back, causing the roof to sag.

My problem with the dealers is they mark the latter issue as fixed by the former solution, when the two are not the same thing.

 

[secret lemonade drinker]

I saw a California ocean at durness two years ago with a broom handle that was exactly the right length, it is funny that my mandraulic beach never suffered this, that is technology and progress

 

[dspuk]

Did a bit of reading to check my hydraulics - when I was in the Army I used to maintain a fleet of Hysters which were not allowed to have any electrics due to combustion reasons at the ammo dumps so we used to run them on hydraulic starter moters from a air tank fitted to their rear. They were forever failing and we used to secretly swap out the starter motor for one we ran off a battery and get them running at a safe distance away. This was always a winter issue due to the increased viscosity and decreased volume of the fluid in the cold leading to hydraulic starter failures (they turned over less in effect).

For the Cali heat/cold related issues I believe (and was what we had) when it's raging hot and you put the roof up the heat has made the hydraulic oil more less viscous (thinner) and also therefore has more volume.

Over time, usually overnight, as the air cools rapidly, so does the fluid in the rams, causing them to decrease in volume, and therefore "sag". Effectively the rams will come in a little as the volume decreases, but no oil is actually leaking back into the tank. This "a little" it seems VW has deemed needs to be 20cm or more. Which is probably very generous. A 20cm sag is a lot.

My guess (and a massive guess at the moment) is that they also have to cater for the other way around - so if you put it up cold and it gets hotter, the rams will expand and stress, so to relieve that stress there has to be a relief in the system somewhere - either a seal that allows it to escape, or a pressure valve.

If you put it up cold though and it stays the same temperature, there should be no real reason, within a day or two, that the volume should change, unless there is an issue with the seals. So to my liking, if the weather is considenant, and you get sag, it's a fault and likely poor seals. If it's the extreme hot to cold or cold to hot, the system is acting as it should to protect the owners and the van.

Lots of theory and supposition here, but reading the various threads on here, feels right.

Would love someone with actual knowledge of thermodynamics to help explain and straw man the above.

Note - I'm also aware air pressure also causing some effect - so high massive sweeps in high and low air pressure could also cause the viscosity to change. There is of course the air bubbles factor as well.

 

[pchmlk]

Your theory sounds reasonable to me. However, viscosity decreases as temperature rises but I don’t see this changing anything.

 

[dspuk]

Your theory sounds reasonable to me. However, viscosity decreases as temperature rises but I don’t see this changing anything.

Sorry, my error - less viscous = more volume. It's thinner. Will edit.

 

[secret lemonade drinker]

So what you need is a gas filled accumulator in the system to equalise out any changes in oil pressure due to temperature/humidity/air in the system, much like I've seen on 6 axis flight simulators, only problem is they weigh a lot! Remove the hydraulics and go with Gas Struts

 

[TripleBee]

The system of the California roof is wrong.
Where the hydraulic system in a convertible car is regulated with shut off valves, the hydraulic system of the California is only regulated by hydraulic pressure.

A convertible car roof is regulated by shut off valves. The idea for it is because it is more complex. First you have an electric motor, disengaging the hooks that keep the roof fixed to the top of the windscreen frame. Then the rear part of the convertible roof is hydraulically operated so it lifts only the rear part. Then the roof cover is hydraulically operated to open. Then the rear part of the roof is lowered, and then the rest of the roof is hydraulically retracted into the roof box. The last part is lowering the roof cover again.
Every step is controlled separately, and apart from the electric motor with the hydraulic fluid reservoir, you also have a block with shut off valves, electrically operated.
The real difference is that when the roof is completely up or down, the hydraulic pressure is released, or isn't under external weight pressure.
If you open the roof halfway, after a few minutes the pressure will be released, and the roof will drop down.

The hydraulic system in the California is much simpeler. It only operates for the rams to extract or retract. Once the roof is opened/lowered, and you stop the opening/lowering, the roof rests on the hydraulic pressure in the system. With the heat, causing the pressure to rise, and making the fluid more fluidly (?), a miniscule internal leak (not really seals, but more balls closing the internal tube in the aluminium mechanical controller between the hydraulic reservoir and electric motor), or pressure release (mechanical) valve will let the hydraulic fluid return to the reservoir, dropping the pressure on one or the other side.

The first rams exploded due to the threaded end cap. When the temperature got too high, the pressure got too high, and the end caps were pushed outwards, breaking the thread, causing the roof to collapse.
The newer rams don't have the thread anymore, but they are riveted (?) togheter.


So now they don't "explode" anymore, but the pressure gets lost through the pump.

If they would make the roof rest when it's completely open, the roof wouldn't sag anymore, and the hydraulic system wouldn't suffer that much in warm conditions.
Now the roof stays closed and opened only under hydraulic pressure. And there is the faulty design of the system.