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1982 Honda CX500TC Turbo
1983 Honda CX650TD Turbo


Sticking Turbocharger Wastegate

Wheeee!! This is not unheard of, and one of my CX650 Turbo's has a stuck wastegate. It is also my most powerful CXT, so says my seat-o'-the-pants dynamometer! I have read how other owners have freed their seized wastegate shafts and valves. Yet, after coming down from an especially wide-eyed ride on my "broken" CXT, I wonder why anyone would want to "fix" this "problem"! Hey, the more grins, the better! So how does one know if the wastegate is stuck? While boosting heavily at or near full throttle, especially in higher gears, the boost pressure gauge will illuminate the two red LED "overboost" segments at the extreme ends of the display, and the "TURBO" logo will flash rapidly. This will all cease as you let off the throttle a little. Note that the P2 sensor, which serves the boost gauge, could theoretically cause this symptom also, but this is less likely. So now you are convinced that your wastegate is stuck, and you are demented enough to want to fix it. Now what?

It is nice to have an air compressor for this next section. With it, you can verify with 100% certainty that the wastegate is indeed stuck, and you can observe the valve coming unstuck as you work it free. You will need to remove: fairing, entire exhaust system, radiator, and heat shields covering the turbocharger. You will need to fabricate a simple pressure tester. Using about a 30 psi dial gauge, attach a T-block. At one end of this attach a suitable fitting to mate up with whatever fitting you have coming off your compressor hose. To the other side of the block, attach a barbed connector which you will later press the wastegate hose onto. Locate the wastegate shaft. Wrap a 1" piece of electrical or masking tape around the shaft, pinching the ends of the tape together to form a protruding pointer. The edge of this tape should be JUST BARELY TOUCHING against the metal arm which secures the wastegate actuator. This will allow the measurement of the distance between the edge of the tape and the actuator arm as we apply increasing pressure. Locate the 5" black rubber hose leading into the wastegate actuator and disconnect it at the upper clamp. BEGINNING WITH THE REGULATOR ON YOUR COMPRESSOR SET TO ZERO PSI, attach the compressor hose to your pressure tester. Attach the wastegate actuator rubber hose to the barbed connector on the pressure tester. IGNORING THE MANIFOLD PRESSURE READING ON YOUR COMPRESSOR, rely only upon the 30 psi dial gauge of your fabricated pressure testing apparatus. SLOWLY increase the regulator until the gauge reads about 10-12 psi. At this point you should begin to see a gap opening up between the tape and the actuator arm. Increase pressure to 18-19 psi. Normal movement of the actuator rod at this pressure should be 2-3 mm. DO NOT EXCEED 19 PSI. If you go through this test and find that the rod moves little or not at all, you have just confirmed a sticking wastegate.

A wastegate can be caused to stick in two areas. The shaft enters the exhaust housing, the other end of which is attached to the actual valve. The shaft can become stuck inside the housing. Remedies include doses of Liquid Wrench or penetrating oils while GENTLY tapping around the area. Use common sense so as not to tap so hard as to crack the housing! Do this while pressure is applied with your pressure tester, and you may actually be able to see the rod "pop" free as it becomes unstuck. Also common is a wastegate becoming stuck due to carbon build-up on or beside the valve seat. If this is the case, shame on you, since regular heavy boosting will usually prevent this from happening! Again, applying penetrating fluids to the valve seat while GENTLY, GINGERLY tapping about the area will often free the valve. You may want to try a light tap on the valve itself to break the carbon build-up.



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