Join the Car Talk Community!

Discussion Rules

Welcome to the Car Talk Community!

Want to ask a question or join the discussion? Great! Join now.

Sign In Register

7.3L Powerstroke funny noise

I have a '97 F-350 with a 7.3L Powerstroke Turbo Diesel, I frequently haul a 27ft bumper tow trailer weighing upwards of 6,000 lbs, which by the way it tows beautifully, but if i am pulling up a long hill or have been on the pedal for a while and let off, then there is a grinding sound that sounds like it is coming from the turbo. My dad and i think it may be some sort of exhaust overflow valve from the quick decrease in rpm or maybe an overspeed on the turbo. No noticeable decrease in power. Anyone have any ideas or experienced the same thing?

Comments

  • edited February 2011
    It very well may be your turbo or the turbo dump valve. WHen you let off throttle after being on it (and under boost) for a while when you let off the pedal the turbo system is supposed to "dump" the high pressure so that it doesnt slam shut the throttle valve....if i had boost in the system when you let off the pedal the pressure will slam into the closing throttle door. YOu may not be properly venting this pressure out via the dump valve this will also cause the pressure wave to back up into the turbo....damaging the compressor wheel.....making it slam into the body of the turbo.

    Do this.....Pull off the pressure tube from the turbo to the engine.....then see if you can put your fingers on the compressor wheel.....check for looseness in the turbo shaft. If it is loose enough with side to side play it may be abe to contact the turbo housing if it is contacting the turbo housing and will self destruct violently very soon if continued to be used. CHeck this.....it is very important and will leave you stranded if the turbo seizes up. CHeck it NOW.
  • edited February 2011
    I typed another response but it didnt make it on here....so here goes again.

    That noise you hear is most likely the turbo compressor wheel contacting the housing....this can be caused by oil starvation, normal wear, or a dump valve malfunction..... If the dump valve doesnt vent that pressure wave it will slam into the throttle valve and or the turbo compressor wheel. If you put a new turbo in make CERTAIN the dump valve works or it will destroy the new turbo. Check that tubo shaft for side to side play....it should be VERY minimal...it will have a little but no more than that.....also look for evidence of the wheel grinding into the housing....you will be able to see it. You might find a destroyed compressor wheel. Let us know what you got...
This discussion has been closed.