Blow-by or lack of blow-by video - PeachParts Mercedes-Benz Forum

funola · #1 07-12-2011, 05:18 PM

I just shot this video of the valve oil filler. Engine was cold and started just a minute before the video was taken. How's it look?

BTW, engine has almost 300K miles with the last 50K on a WVO system of my own design. It starts easily in the dead of CT winters, has good compression and runs great.

CLICK TO PLAY!

scottmcphee · #2 07-12-2011, 09:19 PM

Kinda of hard to tell, but seems OK.

With loose filler cap, pinch off the PCV hose to see if that changes the picture.

kerry · #3 07-12-2011, 09:23 PM

No blowby there.

Joseph_Conrad · #4 07-12-2011, 09:33 PM

Looks good. Just curious, how often do you adjust your valves?

funola · #5 07-13-2011, 12:15 AM

Quote:

Originally Posted by scottmcphee

Kinda of hard to tell, but seems OK.

With loose filler cap, pinch off the PCV hose to see if that changes the picture.

Do you mean the hose from the valve cover to the air cleaner?

funola · #6 07-13-2011, 12:16 AM

Quote:

Originally Posted by Joseph_Conrad

Looks good. Just curious, how often do you adjust your valves?

Every 15 to 20K miles.

otto huber · #7 07-13-2011, 03:58 AM

From what I've read in various posts discussing blowby, you need to get the engine up to normal operating temperature before you pull the cap and take a look.
If your engine runs as well as you say it does, then blowby should be of no concern to you.

funola · #8 07-13-2011, 10:02 AM

Quote:

Originally Posted by otto huber

From what I've read in various posts discussing blowby, you need to get the engine up to normal operating temperature before you pull the cap and take a look.
If your engine runs as well as you say it does, then blowby should be of no concern to you.

I thought blow by would be worse with a cold engine when the rings have not totally seated, but then the oil is thicker when cold so who knows? I'll shoot another vid with a hot engine and the valve cover hose pinched off as a comparison.

scottmcphee · #9 07-13-2011, 10:04 AM

Quote:

Originally Posted by funola

Do you mean the hose from the valve cover to the air cleaner?

yes

funola · #10 07-13-2011, 02:14 PM

This vid is with a hot engine and the valve cover hose pinched off. The cap dances around a little more than the previous video and there is an oil mist that you can't see. It is not smoke but probably from the oil sloshing around and creating the mist.

Does Mercedes have a spec for blow by? I'd be curious to measure mine. How does mine look? Maybe I'll try the garbage bag test and see how long it takes to inflate.

CLICK TO PLAY!

scottmcphee · #11 07-13-2011, 09:35 PM

That looks positively tame compared to some tea kettle vid's

charmalu · #12 07-13-2011, 11:29 PM

Here is the Garbage Bag Blow By test thread. fun read for new members.

http://www.peachparts.com/shopforum/showthread.php?t=193602

Note: has to be a Mercedes Shop approved 30 gallon test bag.

Charlie

funola · #13 07-21-2011, 09:33 AM

I finally got around to trying out the garbage bag blow by test. With a hot engine (after a 40 mile hwy cruise), it tookl 9 min 30 sec of idling @750 rpm to 3/4 inflate the 40 gal bag. I shot a video of the whole episode but was impatient to wait and shut it off before it fully inflated. The video is over 25 MB and not very exciting so I am not going to upload it with my slow internet connection. Maybe I'll shoot another video with a stripper dancing in the background for more excitement.