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#16
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I've got the 617.91 manual and nowhere in there does it say that the glow plug timer varies according to temperature. It says that the light does, but that if the engine is not started, the plugs will continue glowing for up to 90+20 seconds.
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1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13 |
#17
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Considering that the advertised glow period under high temp conditions can be as low as 22 seconds, it is easy to see that a 20 second light duration would be a problem if the entire glow period were not extended in colder conditions.
Last edited by qwerty; 11-10-2012 at 07:55 PM. |
#18
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Quote:
The 617.91 manual is not applicable to your 85TD. |
#19
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I never said it was.
__________________
1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13 |
#20
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Where is this glow period advertised?
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1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13 |
#21
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Quote:
I'm very sure that the glow plug time of 35 seconds is more than sufficient for the coldest expected ambient with an engine that has decent compression. My original question was generated by this statement: Quote:
But, my bad........apparently not. |
#22
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For an '85TD, in the 617.95 Engine Service Manual.
Here is a graph that Google found. (a) is the light duration range; (b) is the total glow period range. Colder temps increase both. http://www.google.com/imgres?q=om617+glow+timer+graph&hl=en&client=safari&sa=X&tbo=d&rls=en&biw=1638&bih=800&tbm=isch&tbnid=t_MSynCopjZypM:&imgrefurl=http://www.mbca.org/forum/diesel-starting-procedure&docid=dF5uPu1zgZt3iM&imgurl=http://www.mbca.org/sites/default/files/7008589_Picture%2525201a.jpg&w=596&h=250&ei=yc6eUJzvJIWO8wSHyYGIDg&zoom=1&iact=hc&vpx=410&vpy=103&dur=302&hovh=131&hovw=313&tx=279&ty=60&sig=106118738943843272756&page=2&tbnh=113&tbnw=270&start=33&ndsp=49&ved=1t:429,r:32,s:20,i:234 |
#23
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Quote:
Safety shut-off = glow duration. Ready-to-start condition = end of light. What is your interpretation of "The safety shut-off is no longer fixed but is the time up to ready-to-start condition (preglow indicator lamp goes out) plus 20-35 seconds?" You have to look at the slope on the graph. See how it's sort of flat above freezing? Last edited by qwerty; 11-10-2012 at 05:49 PM. |
#24
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Thanks for posting that graph. So as I interpret that graph, the 'timer' to shut off is fixed as a certain number of seconds after the light goes out. Since the light stays on for varying amounts of time, the total time energized varies according to temperature.
__________________
1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13 |
#25
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That's the way I see it. Others, obviously, look at the same graph and reach a different conclusion. Perhaps the nearly parallel slope of the lines just doesn't fit their preconceived notions.
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#26
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Quote:
I'm sure that somebody on here will correct me if I am mistaken. |
#27
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On a related issue: Does the motion of the key to the 'start' position override the timer/shut off circuit? In other words, the glow plugs remain energized after the light goes off and the engine is trying to start? There seems to be a consensus that once the key is released from the 'start' position, the plugs stop glowing unless there is an 'afterglow' installed. But if the engine takes a long time to start and the key is held in the 'start' position, does the timer cut off the glowplugs at the end of its cycle regardless of the fact that the engine is trying to start? If so, there's a benefit to starting the timer after the glow light goes out.
__________________
1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13 |
#28
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Yes.
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#29
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Where is there any claim that the glow light remains illuminated for 35 seconds? Kerry's report is reasonably consistent with the data in the 617.95 manual, specifically, a light duration of as little as 23 seconds at -30*C.
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#30
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Here's the FSM on turbo 617 glow plug operation (78-80 and 81 onward)
http://mercedes.thatchermathias.com/w123CD2/Program/Engine/617/15-705.pdf non turbo series type http://mercedes.thatchermathias.com/w123CD2/Program/Engine/615/15-505.pdf It talks about glow plug and indicator duration and safety shutoff of the different model years. Series type non turbo (pre 78) is different than 78-80 turbo, then it changed in 81. I do not see any mention for 85 and assume 85 is the same as 81 through 84.
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85 300D turbo pristine w 157k when purchased 161K now 83 300 D turbo 297K runs great. SOLD! 83 240D 4 spd manual- parted out then junked Last edited by funola; 11-10-2012 at 07:47 PM. |
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