Timing adjustment methods - Page 6 - PeachParts Mercedes-Benz Forum

leathermang · #76 01-21-2011, 01:32 PM

I would like to throw some carbon into this discussion...
one of the main reasons glowplugs burn out is a direct short produced by the build up of carbon.. thus the recommendation in the FSM about reaming the glowplug hole before putting a new one in..
What would be the result in these measurements of the voltage going to these plugs if one were shorted out ?..

AND isn't it more important the amount of CURRENT going to the plugs ?

funola · #77 01-21-2011, 01:46 PM

Quote:

Originally Posted by leathermang

I would like to throw some carbon into this discussion...
one of the main reasons glowplugs burn out is a direct short produced by the build up of carbon.. thus the recommendation in the FSM about reaming the glowplug hole before putting a new one in..
What would be the result in these measurements of the voltage going to these plugs if one were shorted out ?..

AND isn't it more important the amount of CURRENT going to the plugs ?

Carbon build-up is a thermal issue. It cannot electricly short out a glow plug! Isn't that obvious just looking at the glow plug electrode?

leathermang · #78 01-21-2011, 01:56 PM

LOL,
Carbon as a bridge wetted by fuel can not transmit electricity ?

I do understand that carbon is a thermal issue...

but I am pretty sure the FSM also describes it as a ' ground fault' problem with regards to glowplugs...

funola · #79 01-21-2011, 02:01 PM

Quote:

Originally Posted by leathermang

LOL,
Carbon as a bridge wetted by fuel can not transmit electricity ?

I do understand that carbon is a thermal issue...

but I am pretty sure the FSM also describes it as a ' ground fault' problem with regards to glowplugs...

The resistance heating element is encapsulated by a sheath and potted in a high temp compound (magnesium dioxide?). Carbon and fuel cannot get past the sheath unless it's reptured! LOL

Stevo · #80 01-21-2011, 02:04 PM

Quote:

Originally Posted by leathermang

I am sure you are going to be surprised that that IS in the Factory Shop Manual... the 1982 version page 32 ,4th paragraph... subtitled ' age of Aquarius'.

Harump, your saying his method is in there and mine's not?

leathermang · #81 01-21-2011, 02:08 PM

Quote:

Originally Posted by funola

The resistance heating element is encapsulated by a sheath and potted in a high temp compound (magnesium dioxide?). Carbon and fuel cannot get past the sheath unless it's reptured! LOL

I can see that you are going to force me to search my paper manuals manually.. the only downside to paper...

leathermang · #82 01-21-2011, 02:13 PM

Quote:

Originally Posted by Stevo

Harump, your saying his method is in there and mine's not?

I am very sorry Stevo, but it is a ' Cosmic ' thing...
However, the reports lately are that the dates for Aquarius have changed and one new constellation has been added... that may change things completely....
will keep checking that paper manual to see if your method shows up anytime soon...retroactive cosmic printing cloud font they call it...

http://emerize.com/a-change-in-the-zodiac-ophiuchus-the-new-sign.html

ForcedInduction · #83 01-21-2011, 05:44 PM

Infraction bait, ignored.

paddo · #84 01-21-2011, 08:20 PM

I wonder if it's one of those things where an experienced mechanic can adjust the IP timing just by feel/ear - maybe even finer than the recommended methods?

leathermang · #85 01-21-2011, 09:29 PM

Quote:

Originally Posted by paddo

I wonder if it's one of those things where an experienced mechanic can adjust the IP timing just by feel/ear - maybe even finer than the recommended methods?

No.

layback40 · #86 01-22-2011, 08:14 AM

Quote:

Originally Posted by RichC

How many of these cars have you guys ever timed ?
Be honest !

Now go use the search function and look up milli volt method.

Here is a link for you to read.

Setting pump primary timing by milli volt method.

Rich,
This method looks as though it has been well thought out & debated on here plenty. There is a major flaw in the basis of the whole idea. Achieving max combustion temp as indicated by a noisy voltage from a GP that may be caused by the junction of 2 dissimilar metals is far from accurate.
First of all this notion of max combustion temp being the optimum injection criteria is at best questionable, more likely totally wrong for an internal combustion motor. Maximum combustion temperature corresponds with maximum heat production rather than the maximum conversion to mechanical work. What is being achieved is like with a gasser when it pings.
The optimal injection timing is so that the fuel burns rather than exploding & completes is burning just before the bottom of the stroke. This must be realized, it is not a gas turbine or jet engine.
Given that the injection pump is designed to advance the injection with increasing rpm, it is foolish to set the idle injection timing at anything but what is recommended by the manufacturer. To do so could cause the running rpm injection timing to be out. The robust design of these motors allow them to still run well when these "hair brain" miss informed ideas are tried.
If using the claimed apparent thermocouple properties of a GP was reliable, motor manufacturers would be using it as part of their computer engine management systems.

RichC · #87 01-22-2011, 12:44 PM

Most modern engines do use this method.

Mass air flow sensors, and other sensors that tell a computer what is going on.

The milli volt method works well, and many people have used it.

I personally have used it, and know many others that have used it on several cars, and they are all still running quite well.

As grandmother always said " the proof is in the pudding "

Can you prove anything that you have said ?, do you have any experience ???

Can you show us one of these engines that has been harmed by this method ?

ForcedInduction · #88 01-22-2011, 06:47 PM

Quote:

Originally Posted by RichC

Most modern engines do use this method.

No modern engine measures anything but voltage applied to the glowplugs.

RichC · #89 01-23-2011, 07:46 AM

Quote:

Originally Posted by ForcedInduction

No modern engine measures anything but voltage applied to the glowplugs.

did I say anything different.

modern engines have many sensors.

What do you think these sensors are made of ?

Do you think a lot of sensors could be considered thermocouples ?

Will a glowplug act like a thermocouple ?

ForcedInduction · #90 01-23-2011, 08:34 AM

Quote:

Originally Posted by RichC

did I say anything different.

Yes, you suggested modern engines use the glowplugs as sensors.

Quote:

What do you think these sensors are made of ?

Materials manufactured to set specifications and can produce accurate information.

Quote:

Will a glowplug act like a thermocouple ?

Not accurately.
My finger can be used as a thermometer, is it an accurate sensor? Are all my fingers calibrated the same? Do your fingers feel temperature at the same sensitivity as mine?

FYI, a MAF sensor is not a thermocouple.