Does the amount of blow-by decrease with higher mileage???

[zman]

I'm curious as to whether the amount of blow-by ever decreases as the engine gets more miles on it. I have about 20,000 miles on my 2001 and it seems to have just as much blow-by as it did when it was brand new - and the amount is very noticible at idle. I have towed several heavy loads since I bought the truck 15 months ago, so I would think that the engine should be somewhat broken in by now.



Any input would be appreciated. Thanks.



Steve

 

[Chad Sheets]

Should start to taper off now. How is your water temp? Oil and water temps go hand in hand on these. If you have excesive blow by, the oil temp will go through the roof and so will the water temp. There is a way to check it. Its called a monometer I think. Basicaly an overgrown air gage that you hook up to your blow by tube and let the truck run. The blow by will show up as an actual number on the psi scale.



If you are worried about this, you can also have a leak down test on the cylinders to see if the rings might be on upside down, or all gapped in the same place, etc.



Have an oil sample pulled also. If you have that much blow by, the fuel is diluting your oil like crazy. That is the easiest way to go.

 

[BV]

blowby

In my experience, blow by will decrease after engine break in then increase with normal wear of engine components.



There seems to be a few folks that have a lot of blow by and others with very little. I have very little and can not see the vapor even after a long hard pull. As Chad suggested - Pull an oil sample and see what you got. Sometimes blow by is mistaken for water vapor (anti-freeze) and needs immediate attention. Other causes of blow by are caused by incorrect oil viscosity from using wrong oil or if it has been diluted.



There is a spec for blow by pressure that you can check with a Manometer. You can build one pretty easy if you wanted. The Manometer can also be used to check vacuum in air boxes and back pressure of exhaust systems.

 

[zman]

Thanks for the replies guys. Water temp and oil pressure seems to be normal. The vapors are very noticible at idle. Any idea where I might find a manometer for a quick test? An oil analysis sounds like a good idea too - I'm due for an oil change soon anyway.



I'd take it to the dealer since it is still under warranty, but I'm not sure they would have any idea what to do...



Steve

 

[Shooter]

You can get a manomiter at W. W. Grangers. they have a good selecton. Call Cummins and find out what the spec's are or take it to any otr truck shop, they will be able to check it for you.

 

[illflem]

Making your own manometer is a piece of cake. Just make a loop of any size piece of clear tubing, fill the loop with water, connect to your blowby, mark the water level then start your engine and measure the number of inches the water rises. Don't ask me how many inches would be considered normal.

 

[BV]

Manometer

To add onto Bill's post:

Tubing should be 4 feet long and approximately 1/8" inside diameter. Bend into a loop, fasten to a board, fill half way with water or mercury and mark the board from 1" to 8" in 1/10" graduations both up and down starting from the water level marked as 0.



Now keep it level and hook it up. Add the 2 values to get a total. In other words, if you have 1. 2" up then you should have 1. 2" down for a total of 2. 4".



Here is the pressure Conversion Chart:

1" Water = . 0735" Mercury

1" Water = . 0361 psi

1" Mercury = . 491 psi

1" Mercury = 13. 6" Water

1 psi = 27. 7" Water

1 psi = 2. 036" Mercury

 

[zman]

Thanks for all of the info guys. After rechecking everything again, I noticed that the coolant overflow bottle is pretty low, so I'm doing an oil analysis to see if I have any unusual levels of water, soot, or fuel in the oil. I found a shop that said they have a manometer for checking the amount of blow-by. I'll keep you posted. Thanks again!



Steve

 

[SLightfoot]

Drive it HARD....

I agree with the other post that said the blow by should stop very soon now.



I was taken by surprise a bit too, since I didn't realize that you had to work the engine so hard to get it truly "seated".

One or two towing trips isn't enough.



You need some more towing hours to break it in. 20K seems to be just a drop in the bucket for this engine. If you are towing semi-frequently, I would expect it to taper off in the next 5K-6K miles. That was my experience.



I know another thing that people told me (that I didn't believe) is that the towing power increases after it seats properly. IT REALLY DOES!



Once you have that thing completely seated, I think you will be surprised how that engine turns into a towing animal. Now I know why this engine is held in such high regard.



Drive it like you are trying to break it.



Shawn

 

[zman]

Analysis is in...

Based on my oil analysis, it doesn't look like my blow-by is excessive. The non-zero numbers in the analysis were:



Iron: 43

Aluminum: 3

Copper: 3

Lead: 2

Silicon: 11

Sodium: 2

Potassium: 1

Antimony: 2 (what is this stuff?)

Boron: 3

Fuel: . 5%

Soot: <. 1%

Water: <. 1%



There was 5,500 miles on the sample & 21,400 miles on the engine. I have been using an Amsoil two stage foam filter and Stratopore oil filters.



According to the instructions that came with the Fleetguard Monitor kit, I was supposed to sample within 30 minutes of engine shutdown and let about half the oil drain out before sampling. Of course I didn't see the last part and only let about 1 quart out before I took the sample. The Iron seemed higher than some of the analysis reports that have be previously posted, so that might be the result of the sampling screw-up.



I just changed to the Moparguy filter at the last change. I'll do another sample again in 5k miles and see what it looks like.



Steve

 

[Cobra]

blow by

Man I know that I am dumb, but can you explain blow by. I think I know but some early threads were saying to connect the gauge to the blow by. Now that confused me as I was thinking blow by had to do with fumes, vapor, or smoke coming from the exhaust.

 

[zman]

Blow-by is caused by exhaust gas getting past the rings and into the crankcase. This is normal, but blow-by can be excessive. You can check the volume of blow-by using a gauge. You can also check to see if high levels of fuel and soot are found in the oil - also a sign of excessive blow-by. I opted for the oil analysis because I was also curious about the level of wear metals in the oil (when it came down to it, the shop I called earlier didn't have a manometer and I was too lazy to build one).



Steve