I have a 81 240D, have two questions on blowby.

1). Does a valve adjustment reduce any blowby?
2). Does timing chain stratch have any effect on blowby? Would replaceing a timing chain reduce any?

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1981 240D
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By blowby I'm assuming you're talking about into the crankcase?

If so, then the answer is no. Blowby, as in excessive pressure into the crankcase is caused by poor ring seal.

Neither of those affect blowby.

As was stated in the post above.

coolerelmo, I have an 80 240D with excessive blowby. I tried the valve adjustment and put a new timing chain in it and neither had an effect on the blowby, as goatman said it's just the piston rings not sealing properly.

What you can try though, is pulling the injectors (after you get new heat sheilds ) and putting an ounce or so of tranny fluid in the cylender and let it sit for an hour or so. If your rings are just sticky it will free them up and you might notice a drop in blow-by.

If you can, do a compression test before and after to see if they do seal better after the cleaning. Do this on a warm engine and crank it over a couple times before reinstalling injectors to purge the ATF out.

Worked for me for the most part, now it's just a ritual when it comes time to do a valve adjustment.


Hope this helps!
-Nick

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Actually, it isn't.

"Excessive pressure into the crankcase" is not what blowby is.

If you don't want to use trans fluid, Marvel Mystery Oil works as well.

yes, it is.

a valve adjustment MAY reduce perceived blowby in the valve cover.

Hanging valves during peak pressure in the cylinder can allow combustion gases past worn valve guides.

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Bandaid on a gun shot. Leak down test is what's needed.

Sure it is, he might not have written the Britannica definition but it's good enough for me.

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He's just trying to start with me again. He's been somewhat of a troll on the MBWorld forums. Thinks he's the only guy in the world that has any knowledge.


INAPPROPRIATE
B.C.

If the car is already owned and it starts/runs well, worrying about blowby is pointless. There is nothing you can do about it except rebuild the engine, which is a waste if it runs well, and even then it will not stop blowby because its a natural part of every engine.

Do the basic maintenance, get it tuned up and enjoy the long life it has left.

Not if the oil contamination is excessive, or if you're pushing gaskets..

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1987 SDL. The best there ever was.

Ok thanks!

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1981 240D
Click Here To See My Mercedes