Recently I've been working on a SA6D114 komatsu engine used on a PC300-6. And I noticed that the exhaust wastegate valve lever is not moving, I would like to know if the movement of the lever should be visible or not and by the way if it is visible what should be the amount of the movement? And is there any consequence if the lever is not moving?Thx
the only time the lever will move is under very heavy engine loads , it dumps the exhaust valve into bypass to lower the full boost . You still have boost under full load but it limits how much intake pressure the turbo can build , this keeps the head gaskets under the head and lower engine temps alittle. The older motors ran this style waste gate system for years , newer motors control boost by intake pressure and temp with a electonicly controled dump valves or variable geometry turbo that can change the vane pitch and how tight the body around the wheel is.
I think we should make the difference between maximum torque speed and maximum load speed, maybe you are in the second case because you said that the lever starts to move under very heavy engine loads, am I right or wrong?
The waste gate is controlled by intake air pressure and it is common for that linkage to freeze in position, usually partially open. As the load on the engine is increased the governor in the fuel system senses a drop in engine RPM and opens the throttle enough to maintain speed. That additional amount of fuel burn creates more flow on the turbo charger turbine increasing its speed which also turns the impeller faster thus creating higher intake manifold pressure. The rub comes when the engine is running at very high load for longer periods of time such as found in excavators with load sensing hydraulics. The speed of the turbocharger will over run and lean out the fuel air mixture thus creating those nasty byproducts the leaf lickers insist will kill the world and all humanity. The gate is on the input side of the turbine and lets some of that flow bypass around the turbo thus limiting intake manifold pressure. The big problem with these types of turbos is that the byproducts of fuel burn coat the shafts supporting the gate which eventually freezes it in place. Dirty air filters and leaking fuel injectors only add to the problem and then the stuck waste gate either drops your total amount of horse power available, if stuck partially open, or looses the ability to control lean burn, by being stuck closed. I generally saw head gasket problems and found the stuck waste gate while removing the head. The other side of this that didn't help is that the Cummins engine used in this application didn't have the same torque characteristics as the Komatsu engine the machine was designed around. The engine created peak torque at a lower RPM and fuel which corresponds with boost had to be turned up in order for the machine to get the same production. So while the Komatsu engine worked perfectly fine at around 15 inches of mercury for boost the Cummins engine had to run in the neighborhood of 28 inches of mercury for the same output.
I don't know your machine and what drives the wastegate flap, but same principles apply... what actuator connects to the wastegate rod? spring diaghram ? with a small pipe connected from the intake? pressure (from intake manifold) to the actuator diaghram moves the rod to open the wastegate (exhaust side) to stop it opening too early and allowing required boost pressure to be acheived a spring within the actuator acts against diaghram keeps wastegate closed until the maximum boost pressure is reached So it will appear not to move ( due to the spring tension) until intake pressure can overcome it. if stuck closed no where to dump excessive exhaust gases and slow the turbo to control boost levels. while there may not be a feel of power loss,this is a dangerous situation. this could be a leak to the actuator ( intake pressure being vented to atmosphere) or a jammed actuator, or leaking diaghram. If stuck partially open you should find a lack of power. The other side of the rod could be just seized at the turbo itself other controls like boost control solenoids ( acting on the actuator) can refine the control the main thing with rod length is to make sure it's not keeping the wastegate slightly open
I wanted to know how much should the actuator move at this supercharging pressure, is it around 2 to 3 mm?
That is a real good question. I don't know but I would guess it shouldn't have to much much more than that.