2013 Western 4900 DD16 engine brake issues

The engine brake on my log truck is acting up. When the engine is cold it works normally, there is never a high setting cause of the program. Once the engine heats up the medium starts getting weak until it’s non existent, and the low gets really weak and stays weak while the engine is hot. If I’m on a haul rode and keep the engine fan on the medium and low work normally, but once I’m on the highway that trick stops working. We sent it to a mechanic who adjusted the valves, put a whole kit in, and replaced the solenoids, but nothing changed. One of the leading theory’s is at one time the engine got hot enough that we lost some compression between the cylinder wall and the piston. I’m the main driver and I don’t believe I saw the exhaust temperature ever get above 900°F, but other drivers do occasionally drive it for a day or so. Shortly before this happened (about a week or 2) the truck started having power issues, which was going on when the Jake issue started. That ended up being the high pressure fuel pump. This is the first DD engine we have ever had so it’s a learning curve for us.

 

We are using 10-30 blend. We haven’t changed the oil yet, but we have been thinking about it. I forgot to mention the engine was brand new when we got it from auction, and has extremely low miles. Over a year ago it was deleted. The oil pressure is a bit low at idle by about 5psi, but while running I think it is around 55 to 60 something psi once at temp and a bit higher when cold (I haven’t gotten to drive it in about a month as it was passed around between mechanics, so my memory isn’t the best)

 

Thanks, we will probably try this first.