Double Glow? - Page 2 - PeachParts Mercedes-Benz Forum

Jim H · #16 10-31-2005, 06:58 AM

Quote:

Originally Posted by Brian Carlton

...If you turn the key to position III and the plugs remain on (per your scenario), how would the relay know to shut the plugs down when the key is returned to position II??

A fairly simple circuit would do it, far less complicated than the very complex automatic temperature control system...

A 45-second timer, started by moving the key to position II, holds the power contactor and releases it when it times out.

Input from postion III while the timer is running energizes a control relay that stops and resets the timer and holds the contactor itself.

When the key is moved back to position II, position III no longer holds the relay, which then opens and the contactor is released.

Add one more timer, started by release of the holding relay, and you have added an 'after-glow' time function.

Thanks, and let us know what your testing show.

Brian Carlton · #17 10-31-2005, 07:11 AM

Quote:

Originally Posted by Jim H

When the key is moved back to position II, position III no longer holds the relay, which then opens and the contactor is released.

Thanks, and let us know what your testing show.

What would prevent the relay from providing a "new" 45 second time when you return to position II? How would the relay know that you are returning to position II from position III versus going to position II from position I?

I will.

Jim H · #18 10-31-2005, 01:29 PM

Quote:

Originally Posted by Brian Carlton

What would prevent the relay from providing a "new" 45 second time when you return to position II?

You got me!

Of course, the timer is 'smart' enough to time out after 45 seconds and not start over again until you cycle the key from position II to I, and back to II for a second cycle. I don't know how that works, either...

Quote:

Originally Posted by Brian Carlton

How would the relay know that you are returning to position II from position III versus going to position II from position I?

It has to keep track of key position status and history.

Remember, there are two separate inputs, one from II and one from III.

If II occurs and III has not occurred, then start the glow timer.

If II occurs and III has occurred, stop the glow timer and prevent timer from re-starting until all power is interrupted by returning the key to position I and starting over again.

The CD only shows a transistor symbol, meaning "lots of logic in here we are not going to show you."

dlssmith · #19 10-31-2005, 01:35 PM

I often have no access to an outlet to plug the car in, so when it's really cold here, below zero, I cycle the plugs twice. They run about 45 seconds each cycle. Turn the key off and run it again. Boy 90 seconds in a very cold car seems a long time. But, it usually works. You can hear the relay kick off when it's run to the end of the cycle and the interior and dash lights brighten when it shuts off too.

I would like to have the glow plugs running after the engine starts though, it would certainly run better at the beginning of the day.

punkinfair · #20 11-01-2005, 12:54 AM

just wanted to post an update, i left the key in pos. II for about 15 seconds after the idiot light went off, and the engine runs perfectly right away.

for some reason i was always under the impression that the power to the glow plugs went off with the light, so it was a good thing to find out that this is not the case...

PagodaLover · #21 11-01-2005, 01:09 AM

i cast my vote anoother time for those duratherm bosch plugs and relay. however they work, they're better!

Brian Carlton · #22 11-01-2005, 09:09 AM

Quote:

Originally Posted by punkinfair

for some reason i was always under the impression that the power to the glow plugs went off with the light, so it was a good thing to find out that this is not the case...

Don't feel bad. 90% of diesel drivers who don't frequent this board believe exactly the same thing.

Help is what we do here.

300DPETE · #23 11-01-2005, 12:02 PM

I usually hear a "click" about 10-15 seconds after the yellow light goes out. I believe that's the relay shutting off.

Brian Carlton · #24 11-01-2005, 12:07 PM

Quote:

Originally Posted by 300DPETE

I usually hear a "click" about 10-15 seconds after the yellow light goes out. I believe that's the relay shutting off.

Did you time it with a watch? I'll bet it's longer than 15 seconds.

dannym · #25 11-02-2005, 12:02 PM

I've been having a problem on start up and it's driving me crazy. I always have to double glow. If I don't it won't start it will just keep cranking. This is the same hot or cold engine.
It's the same if I wait for the plugs to stop glowing. I did that just a little while ago. I glowed the plugs until the dome light brightened, about 30 seconds, engine temp about 45 deg C, No start. Glowed again for about 15 seconds, started right up. But it ran like crap. No power no acceleration kickdown non functional. Barely able to get to 65 on the highway. I pulled off the highway and shut it off while waiting at the light. Double glowed and it started right up. But this time it ran normal like it never ran like crap just a few seconds before!
This has happened before. It only happens when I glow it once and it cranks without starting. The last time an Italian tune up fixed it.

I checked the plugs and they are all good which puzzles me more. Maybe I'll pull one out and check it.

Anyone have any ideas?

Danny

Brian Carlton · #26 11-02-2005, 12:27 PM

Quote:

Originally Posted by dannym

Anyone have any ideas?

Danny

This does not sound like a glow plug issue. If you have checked the plugs and they are all getting voltage and the resistance is proper, you have ruled them out. The fact that it starts after multiple glows is due to additional heat that is helping to overcome another problem.

It's time to go over the engine, in detail, and check all the basics:

1) valve clearances
2) cam timing
3) injection timing

It's also time to replace the secondary fuel filter.

The symptoms appear to be fuel related and not glow plug related.

dannym · #27 11-02-2005, 01:38 PM

Quote:

Originally Posted by Brian Carlton

This does not sound like a glow plug issue. If you have checked the plugs and they are all getting voltage and the resistance is proper, you have ruled them out. The fact that it starts after multiple glows is due to additional heat that is helping to overcome another problem.

It's time to go over the engine, in detail, and check all the basics:

1) valve clearances
2) cam timing
3) injection timing

These are about due now I'll try to get to them this weekend.
The fuel filters are both brand new, not more than 2 weeks old. It actually runs really well. I get around 24mpg on a consistent basis.
What gets me is the way it runs like crap on one glow and perfect on 2 glows.

I'm gonna pull one of them out. Maybe there carboned up?

Danny

DieselCJ · #28 11-02-2005, 02:55 PM

Quote:

Originally Posted by punkinfair

...for some reason i was always under the impression that the power to the glow plugs went off with the light, so it was a good thing to find out that this is not the case...

Same here.

The light does seem to stay on a bit longer in cold weather.

Anyone have a source for those Bosch faster heating glow plugs?

-John

Jim H · #29 11-02-2005, 04:44 PM

Quote:

Originally Posted by Brian Carlton

This does not sound like a glow plug issue...
...It's time to go over the engine, in detail, and check all the basics:
1) valve clearances
2) cam timing
3) injection timing
It's also time to replace the secondary fuel filter.

The symptoms appear to be fuel related and not glow plug related.

I'll add Primer Pump (air leak?) to the list...

J. R. B. · #30 11-02-2005, 05:09 PM

After reading this I no longer double glow. I start the thing like I did my old D8 Caterpillar--Glow with the second hand on my watch. Smoother idling.