Subject: Re: Time to solve things out Author: webhorn4477 : member since November, 2009 : 37 posts Posted on: 2010-03-07 16:31:42

Sorry to destroy your theory a bit, but there´s quite something i´d like to say to this:

Though, after a vanos repair, the valve timing is improved on an engine, i wouldn´t say that the thus induced process of a better working internal egr does improve conditions in a way that is is the only reason for less sludge buildup.
Btw, i do still get sludge (checked yesterday after we had a new cold front rolling in), just not as much as before.


In my oppinion, the main reason for less sludge is simply the better sealing vanos seals. When they leak, a constant flow of rather cold pressurized oil from the sump runs past the vanos pistons and constantly cools down the entire assembly. Especially when the engine has been cold started, is in the process of warming up and the oil has not yet reached operating temperature. As you know, it takes a lot longer for the engine oil to reach operating temp. than the coolant. Condensation can thus form.
When the seals don´t leak, the only time when there is a FLOW (not pressure) of oil from the sump/oil pump to the vanos assembly, is when the vanos pistons move. This is a much lesser amount of cold oil coming in there, as to when the seals leak and allow a constant, uncontrolled flow.

Additionally, when the vanos does not work as designed, valve timing is not THAT much off that it entirely ruins the engine running characteristics and thus preventing the internal egr completely from happening. It does contribute to it, though.


Also, a working vanos does NOT increase engine temperature. The temperature of the coolant, and thus engine block, is only controlled via the thermostat, as Rajaie already pointed out. It might though have an effect on internal engine components whose temperature is difficult to measure, such as pistons- but their temperature will DEcrease, because of the more effective combustion. The fuel is used better, more of the energy of the combustion is transferred into motional energy (moving piston down) instead of thermal energy ("wasted" in a car engine environment). See more after the next "chapter" ;-)


henrikk wrote: "Coolant can never lower the combustion temperature only the surrounding material."
This is not correct. The amount of heat energy that is created by a combustion is always the same, but the absolute temperature that is reached during this combustion is always directly dependent of the temperature of combustives and the surrounding materials. Which thus means: cooler engine equals cooler combustion temperatures.


henrikk wrote: "There is another side. If fuel consumption gets high then the cooling effect is higher in the engine. Many who replaced the seals regain the fuel consumption to normal or even a lower level, this also proves that the cooling effect from fuel is decreased."
That is not correct. The fuel consumption with not working vanos is higher, because the combustion is not as effective due do bad valve timing. That means, less combustion energy is transferred in motional energy and more in heat. This forces the driver to step more on the throttle, which of course additionally increases fuel consumption.

For explanation, imagine the following setup. You have a container, which is closed at the bottom and open at the top. In this container you put a mixture of one part gasoline vapour and 14.7 parts air. This is the combustible mixture used in car engines, and it will combust when a spark is applied to it. (Actually, it will combust a lot easier when pressurized, but leave that aside for this explanational purpose.) You also have a thermometer, with which you can measure the temperature of the combustion while it happens. You then apply a spark, the mixture combusts, and you note the temperature.
The next thing you do: you fill the container again with the same amount of the above described mixture, and then you put a lid on the container. You ignite the mixture and note the temperature. The lid does fly off.
Question: When was the combustion temperature lower, without lid or with lid? Exactly, WITH lid. Reason: Some part of the energy created by the combustion was transferred into motional energy to blow the lid off.
THAT is the reason why the fuel consumption is decreased: the amount of energy (fuel) applied is due to better valve timing more effectively used for motional purposes, and less is wasted as heat.

This effect is also used on cold starts. The Vanos, very late ignition timing and a rich mixture are used to create very uneffective combustion conditions. This produces lots of "waste heat" and is done to get the catalytic converters and the engine quickly up to operating temperature.
It is correct though, that a hot engine (or better, it´s internal parts affected by combustion like pistons or valves), can be cooled by adding more fuel, because more fuel creates a higher amount of vaporisation coldness.



henrikk wrote: "• Its winter here but l got electric radiator jalousie and for the past 3 years they never opened even in the summer. It will be very interesting to se if they open this summer."

Is this retrofit? Can´t find this in the EPC, not even for cold climate versions. Or do you mean the flaps around on the fan shroud, around the electrical fan directly behind the front bumper? These are not electrical, but close by gravity. They are blown open by wind pressure when driving, if not clogged with leaves.

webhorn

• Feedback - henrikk 2010-02-27 13:39:16 (355 views)
  • Re: Feedback - Rajaie 2010-02-27 13:48:46 (217 views)
    • Re: Feedback - henrikk 2010-02-27 15:09:28 (228 views)
      • Re: Feedback - Rajaie 2010-02-27 23:18:20 (216 views)
        • Re: Feedback - henrikk 2010-02-28 03:15:18 (209 views)
          • Re: Feedback - webhorn4477 2010-02-28 17:36:18 (207 views)
            • Re: Feedback - henrikk 2010-03-01 10:10:37 (212 views)
              • Re: Feedback - Rajaie 2010-03-01 20:35:06 (194 views)
                • Re: Feedback - henrikk 2010-03-02 08:52:28 (208 views)
                  • Re: Feedback - Rajaie 2010-03-03 22:41:49 (162 views)
                    • Re: Feedback - henrikk 2010-03-04 14:09:47 (167 views)
                      • Re: Feedback - Rajaie 2010-03-06 22:43:27 (160 views)
                      • Re: Feedback - henrikk 2010-03-06 14:39:12 (152 views)
                        • Re: Feedback - Rajaie 2010-03-06 22:47:07 (163 views)
                          • Time to solve things out - henrikk 2010-03-07 09:27:24 (170 views)
                            • Re: Time to solve things out - webhorn4477 2010-03-07 16:31:42 (180 views)
                              • Re: Time to solve things out - henrikk 2010-03-08 07:11:21 (192 views)
                                • Re: Time to solve things out - henrikk 2010-03-08 16:12:21 (160 views)
                                  • Re: Time to solve things out - webhorn4477 2010-03-09 15:44:33 (168 views)
                                    • Re: Time to solve things out - henrikk 2010-03-09 17:23:18 (154 views)
            • Re: Feedback - Rajaie 2010-02-28 20:02:31 (184 views)
          • Re: Feedback - Rajaie 2010-02-28 17:35:28 (178 views)
            • Re: Feedback - henrikk 2010-03-01 10:22:35 (214 views)