Low mount turbo control

[Rawze]

just some related info...

There is an inline air filter on some of those older CM870's going to that turbo air controller. They do clog up as the truck gets old.

Also you should be getting a regulated 90 PSI to the supply hose and it should not drop in pressure. If it does then you have a problem in the air system somewhere.. usually the air-dryer unit going bad. .. or the engine fan is leaking air only when it is engaged. It is on the same circuit as the engine fan for most CM870 trucks.

- Build air up all the way 100% .. ensure the A/C system is switched off.. ensure the engine fan is not engaged (is free-spinning) ,... shut the key off, turn it right back on as soon as the engine stops turning. Get out ans see if the engine fan free-spins (it should).. and check it, and the rest of the truck for air leaks while the pressure is ABOVE 90 psi in the dash gauges.

I.E> Anything pulling that 90-psi line down coming from the air-dryer directly effects that turbo arm. Hence, why the red engine maker made the actuator electronic on the CM871's and newer model engines.


If the air supply is not restricted and is steady 90-psi going TO the controller ... and the arm does not have any spots that have higher resistance during its travel range (testing it with plunger removed) .. then it may be the controller itself.

The controller you are describing is notorious for going bad on the CM870's when they get old. If it is more than 5+ years old, investing in a new one is not a bad idea. If it does not clear up the issue, then clean up and keep the old one as a spare for testing.

If moisture or oil intrusion gets into the controller valve, it will make it go bad... so ensure the air compressor is not worn out and putting oil into the air system.. and ensure the air-dryer desiccant filter is not more than a couple years old + check air tanks for moisture at their relief valves regularly (which everyone should be doing any ways as a trucker and your regular inspections. Its called a 112-pint inspection for a d#m,n reason!).