Possible rebuild?

Need a few more specifics. You say it pulls down on hills under a load, how much of a load? How big of hills. What is your oil consumption? Coolant consumption? How does it start from cold? Warmed up? What is the mpg?

 

"I have excessive blowby" Based on what, observing the tube? Did your mechanic take a reading?
"when I start it I see white smoke coming out of the stack" This is normal for a diesel in cool/cold weather.

 

White smoke is fuel that isn’t burnt. It has 3 normal causes.
1. A small amount of coolant on top a cylinder
2. Low compression in a cylinder
3. A bad injector that is pissing fuel instead of spraying.


On a CAT 1 is most common doesn’t mean that’s your problem. But at a million I can assure you the liners are low and it needs uppers for sure most likely lowers.

The smoke out the blow by tube as well as oil is a sure sign it’s wore ### out

 

Also normal when you have low compression.

I think maybe a byproduct of something that causes low compression could cause white smoke and excessive blowby.

But, I'm just a driver. I'd run it till you're losing a gallon every 2k miles.

 

‘At about 2 months, oil psi drops when pulling up a hill’.
Approximately how many miles are on the oil at that time?
Do you use the same brand/weight of oil at every oil change? Have you tried a different brand/weight of engine oil?
What does ‘pulling down’ on hills mean to you? Does the engine drop 100 rpm? 200? 1000?
Do you drop a gear? 2? 4? Years ago downshifting on hills was considered ‘normal’, nowadays it’s looked upon as a ‘burden’, ‘horrible’ ‘my god I have to do that?’