1986 Chevy C10 with 350 turbo trans. it slips at a stop won't hold in place slips until rpms are up and acts like it slips in and out of gear when driving at a steady rpm?

Answer 1

try replacing the modulator it only cost about 15 dollars

The modulator is a hip shot for the most part when the modulator goes bad the tail pipe smokes blue with trans fluid going right out the exhaust and tranny shifts erratic and harsh , that's a sure sign of a bad modulator, I used to race my Chevy turbo 350 with the modulator vacumn line off to give it a more pronounced (harsh)shift when it was floored(WOT) wide open throttle as they say in todays world. This seems to be more of a clogged tranny filter which is located inside the trans pan...drop pan and fluid....when you take down the filter spray out the valve body with a can of "Brake Clean" check for loose bolts in the valve body refer to specs in inche pounds and retorque gently don't forget they are only 1/4 X 20 bolts that snap heads easily...replace the fluid and add some conditioner to the trans at the same time, make sure ya have a clean tight seal on the pan and up it goes....put in two quarts of Dexron and recheck with the engine running at idle warm, keep slowly adding fluid through the trans. dipstick tube until it hits the full mark... put in the trans. ( conditioner with the first 2 quarts of fluid. Good luck hope this bails you out,(by the way the modulator valve is adjustable if it is the large "can" type but don't worry about that until you do the fluid first and if there is no change), work with a Chevy tech if you can team up with an old timer from the 70,s cars.

Peace,

Jay c