gear box modulator

sic 40t · 19-07-2010, 08:31 PM

hi i have a 85 kb lazer about to get it rego. If you leave it running 10-15 min then rev it it blows smoke i thought it was valve stem seals put a brick on the gas pedal and rev it 3000rpm for a one hour all good now. Left it for a whole day then started it sweet but no gear box oil no leaks they told me it the modulater on the gear box sucking the oil into manifold and burning it sound right?. What does a modulator do???????

Peter B - CV8 · 10-08-2010, 11:27 AM

The modulator is a round unit (like a sender unit) attached to the auto transmission - with a rubber hose connection (for vacuum). There is an internal seal to prevent transmission fluid being sucked up into the inlet area & blowing lots of white smoke. You can do a quick check to see if the seal has perished - just pull the rubber hose out of the modulator. If there is fluid inside of the hose then the seal has gone. If it's dry then its ok.
Replacement modulators are around the $40- mark, but make sure you get the correct one for your vehicle year etc - as there are a few different varieties. It's an easy DIY to change - just unscrew the old one & screw in the new one.