Im new to diesels and im buying one tomarrow.
So how can I tell if the truck has blow by or not?

 

I think the only true method is to do a compression test.

Many quick look tests say take the oil filler cap off and just set it back in place. Then crank the engine and if you see smoke that's called blow by.

Others remove the dipstick. But I never understood that one because it's on the bottom.

THEN, they say some blow by is expected and valued. So let's see what say the pro's!

 

What year? If it's an 2000- 02 look for codes with the key trick. It wouldn't hurt to check for blow-by, but there's alot of other things to check for also, If we know what year, we could narrow it down.

 

its a 2001

 

Without starting the truck turn the key position from off to on three times leaving it in the on position and watch for codes on the odometer =P Get the vin and call the dodge dealership for service records to see what the history on the lift pump and injection pump looks like.

 

blow by is detected by using an manometer attached to the crankcase breather tube, the engine must be at a specific rpm and load. this info is in the cummins book. there is a spec for acceptable blow by.