New truck with Series 50 engine has ton of blow by. Fixes?

They probably idled it a lot, maybe stretched the oil changes. You can do everything right with a Detroit. Still get excessive blow by. It’s a problem on them. My valve stem guides were very worn, along with needing an overhead ran. Don’t know if that contributed to it or not. Blow by was so bad, sometimes looked like the Truck was on fire!! Now it’s been inframed. Just like my last Detroit, 50k miles, and it’s already showing up a bit, rebuild kits/ parts are cheap.

 

Sorry to hear that. What truck is it in?

 

Sounds ideal.

 

It will run many more mi. with that bit of blow/by even the trucks that year had blow/by when new!

 

Look there is a lot of misconceptions about blowby, it isn't a truck idling and fumes are coming out of the crankcase vent tube or exhaust, it is only measured when the truck is on a dyno under a full load and measured by a manometer that gives a reading about the amount of pressure that is produced by ring wear.

 

If you have a motor with a fresh-ish inframe laying around in a junk truck there is no reason not to just swap them.

 

I've found that the brand of oil can greatly effect the amount of blowby, and excessive exhaust smoke (due to burning oil, LOTS of oil). My neighbor has an old Ford F800 with the 7.8L Brazil turbodiesel. He had been using Wal Mart branded (diesel) oil in it. It was misfiring, as much smoke coming out of the road draft tube as the exhaust pipe. I had him change the oil to a name brand, and add a gallon of Lucas. It didn't completely fix the issue, but it reduced it by at least 50%. (I do realize that the 7.8 isn't an HEUI, so oil shouldn't cause or fix a misfire.... I can only say what I witnessed). I had an old Ford F-350 wrecker with the International 6.9L diesel, the exhaust smoke was constantly black, billowing clouds. A guy told me it looked like a rolling tire fire. I changed the oil to Valvoline Blue, and it reduced the smoke greatly (I'm not recommending Valvoline Blue in particular, as the formulation has likely changed greatly in 15 years). You need a good, high quality oil, and a thickener like Lucas.