07 870 Jake issues

[Rawze]

What is your oil pressures cold vs. when it is warmed up and weak?. On an old engine, it could be starving if oil up top after it gets warmed up. Also might want to open valve cover and inspect while engine is running to see if there is something bleeding oil badly in the top-end (spun bearing, loose retaining bolts, excess play in rocker bearings, etc.).


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I am sure others have said this too, seems you already know this aas seen in your first post ... Just putting it here for reference for others who may not know ...

With that non-vg series turbo installed, the jake will always be weak (like he mentioned), as the 3rd stage jake on the ISX IS IN FACT mostly reliant on that VG turbo back-pressure for it to function correctly.

Here is how they work...
Stage1 == only one solenoid fires (3 cylinders).

Stage2 == BOTH solenoids fire (all 6 cylinders).

Stage3 == BOTH solenoids fire AND THE VG TURBO is used to generate a severe restriction in the exhaust manifold (+ extra intake boost pressure), forcing exhaust gas to move from one cylinder to the next, and get re-compressed a second time, dramatically increasing the engine breaks strength.

So... Without a VG turbo on it, stage 3 is pretty much 100% defunct, stage 2 suffers greatly in its strength, and stage 1 just about operates normally.