Detroit blow by

If it's just coming out the bottom through the breather tube, nothing much to worry about. Some of those Detroits did it lots and ran for years.

 

What?

When idling or when under a heavy load?

Blowby is only measured under a heavy load and at a high engine speed like 1800.

What you see is water vapor heating up and escaping the engine.

 

I blow by Detroit whenever possible.

 

Original DD series 60 in the truck to the left started with more and more serious blowby at about 700,000 miles. Putting out lots at idle when I took it to Detroit and they measured it. Nothing unusual. Dropped reman in at 1 million. It now has about 700,000 and here we go again. Don't worry if it isn't using oil.

 

I had a similar issue with my CAT, and I changed brand of oil. Blow by disappeared.

 

It's strange how that works, Iv'e seen that same kind of thing with my cat. Loves Rotella but put moble one in it and start getting blow by.

 

I switch to Guardol ECT 15-40. It's a synthetic blend. I ran Delo for many years.
But both chevron and shell have changed there formula for the newer emission stuff. A buddy of mine was a firm with rotella on his b model and started having the same issue like I did, blow by, he switched to Guardol, and blow by went away.