supercharger clanking

sizemoremk

Registered User
Got a clanking sound at low engine speed with a 93 supercoupe I just got, then when I shut her down there is an "applause" sound comming form the supercharger itself???

I took off the SC belt, and clanking went away, but I do have a very erratic idle..... Would an erratic idle cause SC clanking??

Going to diagnose the idle problem next....

Thanks!
 
bypass valve or nose coupler

@ idle vacume holds the bypass valve open..if the bypass valve doesn't open ...supercharger will make cavitating noise..and will allways be in boost mode :eek: look for a disconnected vacume line to bypass valve ...also may be causing vacume leak ...hence the bad rough idle....nose coupler is a more common problem with age...and 2 different styles of couplers were used ... a soild one and a spring loaded coupler ...I've pulled both of 89-90's ...you need to turn the SC pulley ..back and forth ....and you will beable to tell .....if it is a direct connect [solid coupler].. or if there is a spring.. taking up the load ....before it picks up the rotors.... in the SC.. as you turn the SC pulley ...if it's a solid coupler.... you won't feel the snap [tension] of a spring loaded coupler ..and with a soil coupler ...you shouldn't have any slack turning the SC pulley back and forth..if you do the coupler is shot...and needs to be replaced ...if it's a spring loaded one ...you can bend the end tabs ...of the spring back ...and it will put more tension on the spring...and get rid of the knock knock sound @ idle ...which mine was doing ...and I also think it was setting off the knock sensor ...making idle difficult...at times......lastly check the oil level in the blower...pull the allen key plug out ...and make sure oil ....is just below the threads in the case ...if it's low ...buy GM supercharger fluid .... from a GM dealer...much cheaper than ford....and if low .....check the front seal [unseeable behind the SC pulley] for signs of a leak ..look on the underside of the hood ... on the insulation for being oil soaked and down by the cam sensor on the timming cover/waterpump ..oil ....the front seal maybe blown out ...and there's not enough oil left in there ..causing a rough drive by dry bearings and gears .......ok one more lastly came to mind ....check SC belt ...still within range .....dave

ps: on pulling the allen key plug out ...I've stripped a couple of heads off ..and have found the plug comes out easier if the supercharger is warm...but need to check the oil cold ..it expands as it gets warm and will spill all over the place ..if it's full .... nothing smells as bad as used supercharger fluid ;)
 
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