3B Crankcase vent help

[Profibus]

Hey, I'm having an issue with my 3B (88 Bj75).


Please keep in mind, I'm no diesel guy here, so my knowledge is lacking.

Coasting downhill I notice an exhaust smell fill the cab. Only when coasting, there is no other time or condition I've noticed the smell. Crawled under the truck and noticed some smoke coming from the crankcase vent hose. I took a video and posted below. Does the amount seem excessive? I've done some reading on here and it could be relatively minor like a stuck ring, or it could be a full rebuild. I'm going to test compression this week to give myself a better picture. What are some easy things I can do that would solve the issue, if it is minor?

Video has sound. Ignore my compressor running in the background. I turned the idle up as well to make the smoke more noticeable.

 

[roscoFJ73]

How many klms on the engine? Looks a bit much to me

 

[Profibus]

257,000km if the odometer is correct. I'd like to soak the rings first before I get carried away. Anything you'd suggest I try as well? I'll be testing compression mid-week

 

[roscoFJ73]

Try and ascertain whether its the rings or valves with a compression test or leak down test. A teaspoon of oil into the cylinder would increase the compression if its ring problem and mke no difference if its the valves.