In the midst of replacing the headgasket on a 1979 300SD. Bought the car cheap as the PO overheated it and didn't want to pay the money to find out why it was blowing white smoke. Have a 1980 300SD parts car and the head from that one is getting the once over at present and when complete, being installed on the '79.

Wonder if anyone has any comment on the teardown pics from this weekend. Primarily the moisture & rust under the valve cover and the massive amount of carbon on the frontmost cylinder (#1?).

Thanks!

https://picasaweb.google.com/116318077355015592300/HowISpentMySuperBowlSunday2011#

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"Opportunity is missed by most people because it is dressed in overalls and looks like work" - Thomas Edison-
1979 300SD
1975 450SL
2014 Ram Cummins Megacab (tow rig)

The cylinders / pistons that are clean had water getting into them. Consequently, you had white smoke out the tail.

But it is quite possible that some cylinders remain clean enough to see markings on the piston even before that happened.


The 'carbon' in #1 is from large chunks of gooey intake droppings - a mixture of crankcase gases, oil and EGR excrement.

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If one cylinder has extra buildup you might want to have your injectors check'd out. Might be a good time to head off any problems.

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1996 s10 zr2 with a 6.5 turbo diesel
1996 c2500 suburban with a 6.5 turbo diesel
1981 300sd with a turbo 617
Monte carlo figure 8 car

No coolant got into #1 that's why it was still carboned up. No egr on a 79SD so that doesn't explain it.

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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

But coolant got in the other 4 cylinders?

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1996 s10 zr2 with a 6.5 turbo diesel
1996 c2500 suburban with a 6.5 turbo diesel
1981 300sd with a turbo 617
Monte carlo figure 8 car

oh, thank you.

but it does have a crankcase breather to the intake manifold.

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So, the head gasket went on the rearmost and ironically cleaned the pistons & rings? Not too sure how long it ran in an overheated state but my guess is not long based on what the PO told me. What kind of lower end damage could have occured? After I wiped away the carbon on #1 this is that it looked like: https://picasaweb.google.com/116318077355015592300/HowISpentMySuperBowlSunday2011#5570766748589226514

More a function of bad injector? The "stain" is burned into the top of the piston.

All the rings have about 1/2" of darker area at the top of the cylinder wall, a couple showing material (burnt gook) raised slightly. What can I use to clean the pistons and inner walls? Parts cleaner on a rag ok? (mineral spirits).

Thanks - first time going this deep into a motor.

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"Opportunity is missed by most people because it is dressed in overalls and looks like work" - Thomas Edison-
1979 300SD
1975 450SL
2014 Ram Cummins Megacab (tow rig)

that stain is on all pistons, regardless of failures

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a compression test would have been cool before you pulled it apart, number one could have extra carbon for allot of reasons. A bad injector would be the most desirable. Coolant only cleans the cylinder it is being leaked into but it does do a very good job.

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1996 s10 zr2 with a 6.5 turbo diesel
1996 c2500 suburban with a 6.5 turbo diesel
1981 300sd with a turbo 617
Monte carlo figure 8 car

I'd thought about doing a test but would have had to dink around with a valve adjustment so just decided to assume worst case scenario. I guess I'll rebuild the injectors just because I don't know what the history is.

__________________
"Opportunity is missed by most people because it is dressed in overalls and looks like work" - Thomas Edison-
1979 300SD
1975 450SL
2014 Ram Cummins Megacab (tow rig)

Never a bad idea it is very convenient now and it should run better. When i do stuff like what you are doing i like to use atf to clean off the pistons and cylinder walls, just have to be careful you can never be to clean.

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1996 s10 zr2 with a 6.5 turbo diesel
1996 c2500 suburban with a 6.5 turbo diesel
1981 300sd with a turbo 617
Monte carlo figure 8 car

Thanks Josha. This is actually turning into a fun/expensive project. Lots of "while I'm in there I might as well do..." Had the starter rebuilt, rebuilt the turbo myself, new water pump, rebuilding the vacuum pump (thread here about that also) and now injectors. Not too much left after that except the dreaded ACC! I also need to get a line on the upgraded engine cooling fan (not the electric one) also.

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"Opportunity is missed by most people because it is dressed in overalls and looks like work" - Thomas Edison-
1979 300SD
1975 450SL
2014 Ram Cummins Megacab (tow rig)

Yea the upgraded fan is 4 shorter bolts to remove it and a wiring kit to run the electric one just my .02

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1996 s10 zr2 with a 6.5 turbo diesel
1996 c2500 suburban with a 6.5 turbo diesel
1981 300sd with a turbo 617
Monte carlo figure 8 car

Happen to have a link?

__________________
"Opportunity is missed by most people because it is dressed in overalls and looks like work" - Thomas Edison-
1979 300SD
1975 450SL
2014 Ram Cummins Megacab (tow rig)

I would clean the corroded cam lobes with 800 grit sand paper, clean/oil, wrap it in oiled paper in a plastic bag for later need/sale.



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