Noise from transmission after dyno-test

[Jesper]

Dear forum,
 
After a dynotest with engine adjustment and afterward an output test, i have unfortuately got an ugly noise from the gearbox or converter. The noise is only there, when the engine is pulling (when the car drives). It sounds a bit like a piece of sheetmetal hitting every second spoke in a bicyclewheel...

I did check the flexplate, and there are no cracks or missing parts- or parts hitting each other...

There aren't any other problems, the tranny (th 350 standard gearbox) is, apart from this noise, working perfectly, and the engine is pulling allrigth..

Anyone with a good idea to the cause?

Best regards

Jesper, Denmark

[Rick68]

Make sure the inspection cover is not hitting the flywheel.

[flyingskibiker]

Check around your fan and pulleys/belts.  Maybe the dyno guys knocked something loose???  Could it "just" be a rattle from under the car?  Maybe something was bent driving it on/off the dyno???

[CNorton]

Dear forum,
 
After a dynotest with engine adjustment and afterward an output test, i have unfortuately got an ugly noise from the gearbox or converter. The noise is only there, when the engine is pulling (when the car drives). It sounds a bit like a piece of sheetmetal hitting every second spoke in a bicyclewheel...

I did check the flexplate, and there are no cracks or missing parts- or parts hitting each other...

There aren't any other problems, the tranny (th 350 standard gearbox) is, apart from this noise, working perfectly, and the engine is pulling allrigth..

Anyone with a good idea to the cause?

Best regards

Jesper, Denmark

[CNorton]

Sorry for the double post.  It's still early in the week.

If the problem emerged immediately after a dyno pull and occurs only under load, I'd start by checking the driver's side motor mount.  If it is in the process of giving up, the motor is probably rocking to the right under power and the longest fan blade is hitting the closest point on the fan shroud or something of a similar nature.

good luck,

c

[Jesper]

Dear all,

after some ionvestigations, i have now solved the problem; as described, it ocurred only when accelerating...
I first checked the tranny-oilpan and the filter for debris - nothing. At all...

The i closely checked the flexplate for cracks aso... nothing. By coincidence, i noticed some blank metal marks on some of the tooths on the ring gear. I looked up on the startermotor, and noticed, that the centerbolt of the shift fork had fallen out... this caused the starter drive gear to "slash" back and forth- and of course, when accelerating, the starter drive gear hit the ring gear- causing this very (expensive) noise...   

After mounting a new bolt in the hole, the car now runs smooth again- and i enjoy my 230 brake HP, measured on the wheels, in the beautiful danish summer ! :-)

Best regards, and thx again for all of your inputs to my case

/Jesper