Rawze.com: Rawze's ISX Technical Discussion and more

Hi all.
I am having a problem with engine brakes of my truck, they work better when its engine is cold, but they do not work when engine warms up.
cummins guy changed rocker arms, shafts and couple of engine brake rocker arms, as they said, oil was leaking thru the wear on shafts and arms,
i changed sensors and wiring harness for sensors (under the rocker cover). Oil pressure on the dash shows little over 30 with at operating temp.
still engine brake doesnt hold or slow down speed of truck even with empty trailer.
pls suggest if some one have same problem or have any solution,

engine warm up, oil warm up and get thinner. - maybe excess clearance between rocker and shaft.

can test by put 1 gallon of 85-140 gear lube in engine to thicken oil and see if engine brake gets better warmed up.

Yes there was excessive clearances in rocker arma and shaft, but cummins tech changed shaft and most of the arms. ( Rest of them they said meet the specs). And I also use lucas in oil.

I turbo has to do any thing with engine brakes?
Or the Tractor Abs light?

Thanx for the reply though

I would run my own overhead and double check their work...

make sure the wiring harness is still ok.

Which model engine do you have? Cm870 or cm871?

Do you have fuel in your oil? And has anyone operated the engine brakes manually with the valve cover off and the engine warm? Also check for air bubbles between the rockers- This would suggest your oil pump is aerating.

Harness is fine.
I dnt think there is fuel in the oil. I will check the bubbles for airation but if thats the case my oil pressure guage should fluctuate .
Cummins guy checked the brakes with brake out harness. And they think its fine. After they replace the rockers and shafts, brakes do get louder. But they dont hold the speed of truck on hill even with empty trailer.

(03-21-2019 )manny87 Wrote: [ -> ]...
guage should fluctuate .
...

that is an incorrect assumption. Those gauges in the dash, tied to the engine data have as much as a 3 seconds delay in them.