auto transmission prob in 1966 GT350

Hi there - wondering if anybody else has had this problem and has been able to fix it. After my Shelby has been left for a week or two and then driven, on first start up the auto trans seems to pressurise and fluid rises up the dip stick tube, out onto the tri y's and onto the floor. Not alot but enough to be quite noticeable........ maybe the equivalent to 3 or 4 teaspoons full. It's got Automotive Automatics (my local experts) beat!. It's just been serviced (new filters/fluid and pan gasket) and it doesn't appear to have a stuck or blocked vent cap. Where do i look next chaps ????? My Shelby still has the original engine and auto but has had a Paxton added in the mid to late '80's by Craig Conley (when he owned it.) - any help is much apprecaited. thanks.

 

thanks Mike - im pretty sure that the dip stick and tube are
correct for a c4.....any other idea's. ive considered taking it out, dismantling it and checking for any possible blockages but the thing runs so well...... it's
only on first startup that's a problem. thnks for your help anyway. cheers

 

will do Mike. Hot - I check the trans fluid while it's running ......seems to be plenty there on the stick. thanks for your help.

 

It appears that the vent pipe was partially blocked,the seal on the dipstick was not seating properly in the dipstick tube, and there was not enough trans fluid - so thanks to Mike for a few timely tips and problem fixed. Thanks.