What's the deal?

Greg rubbing off on you? :D

oh, you mean about reserving the stupid spaces? well, actually, I never really thought about it before I saw him do it. In this case though, (and I must admit I struggled with it for a little while before i did it, but only a little) I really would have lost the continuity of the pictures if i didn't. And I want it to be useful, I really do. And Brian, are you accusing me too of running on and on about stuff after i've already made my point, just so i can make sure that everyone that can read a second grade primer will understand every point I'm trying to make, without fully knowing that if i continue to run on and on like this I'll, well I'll just,..........oh, s***! :o

Yep, exactly like that. :D :D

That set of bags is the funniest thing I've seen all day. I was waiting for the explosion! :eek:

Now, the question begs as to why the engine did not shut down.

Either the blowby was leaking out somewhere or you have pressurized the crankcase, correct?

So, if the crankcase was pressurized, the engine should have shut down, based upon the theory that the shut-off diaphragm will be pressurized on the engine side, which is the same as applying vacuum from the outside.

Thoughts???? :confused:

Additionally, there appears to be no baseline for your engine because there cannot be a point in time where the bag becomes "full", agreed?

OK, I'm slow. What does the inflated trash bag tell us exactly?
I think I got it wrong on mine. The bag melted on the exhaust pipe before it filled all the way. :eek:

:D :D :D :D

If the bag inflated to a certain point (full???) in 300 seconds then we would have a baseline on what a rebuilt 617 would do for blowby.

But, in this case, the bag fills up and then stretches itself out and the stops filling. So, we really don't have a proper baseline because the volume is indeterminate.

Pretty funny to watch it, however. :D

Brian, you identified the exact point I want to clarify and improve upon. If you look at the pictures, they were taken at ROUGHLY 1, 2, 3, 4, and 5 minutes after start. IMHO, somewhere between 4 and 5 minutes was when the bag was "full", probably closer to 4 minutes. Just like when you inflate a pool float, there is a point where the thing looks nearly full, and then, in just a few seconds, all the little wrinkles pull tight. It's at this time that I propose to call the bag "full". Not the most rigorous test, for sure, but simple enough to be done in someone's driveway that has the car for sale....maybe a few "telltales" made with cellophane tape or paper clips at the corners could be helpful in defining full. No test is very useful if it's not reproducable, and if it's done by several others, I expect we'll all learn something. I for one would like a decent guideline to check the next MB I buy.

I recently had an opportunity to check out the blowby on a recently rebuilt engine - unfortunately, the owner did not know the mileage covered since rebuild.
When I removed the oil filler cap from the valve cover, there was NO oil smoke!

On my 300D with 295 000 km on the ODO, when I remove the oil filler cap, I get a wispy oil smoke , like if I had removed the lid from a small saucepan of boiling water.
On the 380 000km engine which used to be in Josephine (wife's car), when we were bring home the "new" vehicle, we saw smoke coming from under the hood. After reconnecting the breather hose to the aircleaner housing, the smoke stopped. Removing the filler cap caused a serious visibility problem.
That engine has since been replaced.

I hope that these descriptions are able to be visualised by Forum members.
Tony

"oh, you mean about reserving the stupid spaces? well, actually, I never really thought about it before I saw him do it."

I have been called an innovator...

" would have lost the continuity ..... if i didn't. "

Exactly, I hate it when my answer makes the first post of the second page... I don't think many people go back and see what I was referring to...

"running on and on about stuff after i've already made my point,"

Surely some of the blame should go to those people who will continue to post misstating the physics or misinterpreting what I have said... causing me to think I have not done a good job of description or logical presentation.

So if I got a car with tons of blow by could I inflate pool toys with it? :D

Cool experiment though, I might try that.

Great way to inflate the kiddie pool without passing out from hyperventilating. :D

....................all of the blame should go to those people. :mad: :D

yes, except in my case at least, I really often don't do a very good job communicating - I find myself misunderstood all too often. Some of it has to be me. :( .....Anyway, who wants to do the blowhard, oops, :rolleyes: I mean blowby test?

One of the Cummins turbodiesel forums has the name of the proper instrument for measuring blowby. It even gives instructions on how to make one involving a hose filled the water. There are precise limits for the amount of blowby on a Cummins to determine whether a rebuild was required. I think the blowby was measured in litres.

This test is not too bad but to have a standard one might have to cool bag with water spray. The plastic is going to get weak enough to stretch from the heat contained in the blowby otherwise. Tying a piece of thread of constant length around bag and timing to moment thread breaks might also help eliminate a few variables.At least you have established some indication of how much a tight engine is producing. Good effort. :)