Amount of blow by...useful or not?

[015point9]

Real close to 100,000 miles.  Wondering if knowing the amount of blow by from slobber tube might be useful as to the health of internal parts at later date.  A bench mark number to refer to.  

Only way I can think of to measure would be to measure amount of blow by raises a water column like a rv propane tester.  (Versus an actual psi gauge, that might mess up a gasket, but not sure. ) 

Any info helpful...thanks.

[dripley]

I have never heard of anyone trying to get measurement of the blow by. You can take the oil cap off and set it upside down on the whole and should not blow it off. Maybe there is way but never heard it discussed. But at 100k I would not expect you to have any issue unless you mistreat the hell out of it. As some would say its just getting broke in. I am 445k and while I probably have a more than I did 345k ago it is nothing I worry about.  The engine is still strong. 

[Mopar1973Man]

2 hours ago, dripley said:

I am 445k and while I probably have a more than I did 345k ago it is nothing I worry about.  The engine is still strong. 

 

Exactly.  This is a summation of all blowby in the engine. Like @jlwelding learned years ago you can have a cracked piston creating a misfire problem but still pass the blowby test even though the cylinder was dumping its compression in the crankcase. This is not a good way of measuring cylinder health.  If you want to know the cylinder health you can do a compression test or leak down test. Most opt for the compression test being its easy to do. A typical engine should be 400-425 PSI in good shape.

[015point9]

Thanks folks

Guess my thinking not good.  

(I was pondering the aspect if i could measure how much by pass now at 100,000 then I would have a bench mark so to speak for later miles. )

 

Won't do any Good now (before you guys blew out of the water?  ???)was going to drill a hole at the end of a plumbing plug and put in slobber tube, then tap in a nipple and then with vinyl tube put in some water (sanitary "S type thing at bottom so water didn't go into crank case) and with vinyl tube marked in inches...to see how much blow by pressure is being created.  Thinking that blow by only gets worse... then i would know at later mileage if there were  meaningful changes in compression... via how much blow by.

 

Ok... any good info or short cuts doing compression tests.  

[Guest 04Mach1]

Blow by can be measured with a special water tube tool... I forget what the tool is called. 

 

The only engine that I've seen fail the test was a DT466 with a bad air compressor. The 07 5.9 I posted about had broken rings on pistons 1 and 4 but still did not present a blow by issue just dead cylinders.

[Guest 04Mach1]

 

 

Edited because I remembered the tool is called a manometer. Blow by testing . Every engine is different and has a different spec. No engine has zero blow by.

Edited June 17, 2018 by 04Mach1

[015point9]

15 minutes ago, 04Mach1 said:

 

 

Edited because I remembered the tool is called a manometer. Blow by testing . Every engine is different and has a different spec. No engine has zero blow by.

 

Yes manometer, thanks for remembering.  Had to make one to test propane in rv stove years ago.