1991 MB 350SD Delvac 1300 - 1000 miles

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JHZR2

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Ive discussed in other threads about my recently acquired 1991 Mercedes 350SD with the "rod bender" engine. The head gaskets are known to be weak due to insufficient material in some key places, due to the engine merely being a 3.0L block bored out.

The car had oil in the coolant, just the slightest amount, which could be literally absorbed out of the recovery bottle with a paper towel. But it would readily come back.

In theory, this means that retained coolant pressure would force hot coolant in the oil. In the few thousand miles I drove the car since buying it, it never lost coolant, and the cooling system worked well.

All the same, I pulled a UOA to see if there were signs of coolant in the oil. To my surprise there is not.

[Linked Image]


The soot % is surprising. I do think delvac 1300 has some sodium and potassium in it.

Thoughts?
 
Meaning the leak takes more than the pressure produced by the cooling system to leak but the higher oil pressure will open it up. Lucky break I would say.
 
Originally Posted by JHZR2
The soot % is surprising. I do think delvac 1300 has some sodium and potassium in it.

I wouldn't think so, but without a VOA from the same lab, not much can be said. Besides, even a tiny amount of residual coolant could have you seeing tiny sodium and potassium numbers like that.
 
Originally Posted by Garak
Originally Posted by JHZR2
The soot % is surprising. I do think delvac 1300 has some sodium and potassium in it.

I wouldn't think so, but without a VOA from the same lab, not much can be said. Besides, even a tiny amount of residual coolant could have you seeing tiny sodium and potassium numbers like that.


Perhaps.

PQIA shows Na in it.

http://www.pqiamerica.com/June 2014/ExmoDelvac13001540.htm

Potassium maybe not as much... hmm.
 
Yes, that tiny amount of sodium, on their VOA, not sure either. That's certain not at an ordinary additive level, at least from a sodium additive package like we're used to seeing. At that level right now, I wouldn't sweat it. You already have a good handle on the issue.
 
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