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#1
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Bewildering Crankshaft Discoloration...pictures included
I have here two pictures of my crankshaft during my recent oil pan replacement. Notice that the discoloration is only on the crank and not on the caps. Do you guys have any idea as to why this might be? For the past couple years my car has had the oil cooler bypassed, could this be a result? The PO had it done, not me. Right now I'm trying to find the $100 for a used cooler and hoses. In the mean time however, this has to do.
Thanks David
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_____________________________________________ 2000 Honda Accord V6 137k miles 1972 300SEL 4.5 98k miles _____________________________________________ |
#2
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does look
like heat discoloration. i dont really know if that is normal or not. i am guessing not. by all means reconnect the oil cooler. it is one of the many keys to longivity.
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. |
#3
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That's what my uncle thought but he said the wierdest thing about it was that it was limited to the crank and not at all on the caps. Why wouldn't it also be on the caps? Is there some reason that the main bearing would have heated up more than the rod bearings?
Thanks David
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_____________________________________________ 2000 Honda Accord V6 137k miles 1972 300SEL 4.5 98k miles _____________________________________________ |
#4
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Unless they welded up that journal and reground it in the past? thats very odd, it takes a LOT of heat to get like that.
__________________
Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche |
#5
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I have the PO's service records and nothing indicates any major engine work. Just the usual monovalve every 3 years and pesky electronic things.
Thanks David
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_____________________________________________ 2000 Honda Accord V6 137k miles 1972 300SEL 4.5 98k miles _____________________________________________ |
#6
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You should pull a rod cap off and examine the bearing shell and the bearing journal of the crank. Look for streaks and gouges where foreign material could have gone through the system. Next take a micrometer and "mike" the crank journal. Make sure you "mike" it twice 90 degrees apart so you can check for out of round. Go and no-go tolerances are listed in the engine manual.
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1983 300-D turbo 1985 300-D turbo 1959 Harley Panhead chopper 1929 Ford coupe restored I hang out with Boneheaddoctor at Schuman Automotive OBK#5 All liberals are mattoids but not all mattoids are liberal. Last edited by J. R. B.; 07-05-2005 at 11:43 PM. Reason: confusing grammar |
#7
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Well now I have the pan back on and it would take some major persuasion to get me to redo that job. That was a nightmare!
Thanks David
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_____________________________________________ 2000 Honda Accord V6 137k miles 1972 300SEL 4.5 98k miles _____________________________________________ |
#8
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I'm guessing that discoloration is not from engine heat, but rather from manufacturing process heat.
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The Golden Rule 1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later) |
#9
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Quote:
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Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche |
#10
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Quote:
Dark yellow--480 Light purple--530 Dark purple--550 Dark blue--570 Red heat visible in the dark--752 Red heat visible in daylight--975 Dark red--1292 Cherry red--1652 Bright cherry red--1832 Orange yellow--2192 White welding heat--2552 Brilliant white--2732 Dazzling white--2912 One must realize though that this is inacurate as one person will percieve colors differently than the next. Also the temps I have given are from an older edition of the book. By looking at his pictures I would say that the crank was rather hot in localized areas that is why I suggested pulling a rod cap off and miking the journal.
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1983 300-D turbo 1985 300-D turbo 1959 Harley Panhead chopper 1929 Ford coupe restored I hang out with Boneheaddoctor at Schuman Automotive OBK#5 All liberals are mattoids but not all mattoids are liberal. |
#11
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Quote:
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1983 300-D turbo 1985 300-D turbo 1959 Harley Panhead chopper 1929 Ford coupe restored I hang out with Boneheaddoctor at Schuman Automotive OBK#5 All liberals are mattoids but not all mattoids are liberal. |
#12
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Mercedes used to heat treat the cranks by gas flame...they now do it with induction.
The 'blueing you see here is the result of factory hardening ...the bearings would be shot by now if the had reached the temperature needed to make the 'blue'. Mecedes has a fische about this on the 6 cylinder turbo 300SDL engine to explain which components are interchangable. The connecting rods where hardened too. .
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[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ] "A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money." |
#13
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Quote:
__________________
Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche Last edited by boneheaddoctor; 07-06-2005 at 11:58 AM. |
#14
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The reason I'm up to speed on the 300SDL motor is that I have fully overhauled one last January..new liners/pistons, used crank/used rod set......and it returned last week for it's oil service and hood pad.
During the build, ( which was due to the oil pump eating a piece of metal at 70 mph on I-35..)..I had a lot of different input from other sources about the construction and fitting of the early and late crankshafts and the use of re-sized conrods......I got hold of the factory fische, and it explained in detail the engine numbers and crank id's to allow using later made components. Mercedes changed the width of the journals and the rod, to increase the strength of the crank......they changed the hardening process too, to electric induction from flame hardening with information on the Rockwell of the metal, so information was required to allow rebuilds with compatable components along with increase in head deck thickness.. They also changed the rifle drilling and a few other discrete parts... All in all, it told me that next time I get a blown 1987 and up 300SDL, find another engine and swap it out......but do not rebuild the siezed motor. .
__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ] "A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money." |
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