Slight hesitations in 3rd gear at approx 40 - 60 KPH

SANDYERIC

MEMBER
1940 CHEVROLET ASTRO

My Astro Van (1998, 195,000 Km) has had a slight miss (transmission I think) when I drive it in third gear at 40 to 60 KPH. It clears up in the drive gear (4th or overdrive?)
It has been this way for about 4 or 5 years now and hasn't presented a problem 'cause I just make sure I drive in "D" or overdrive. However, it seems to be starting to do it in drive now as well!
I know that at one time transmissions had a 'modulator valve' that used to get dirty. This was one of the vacuum connections between the motor and the tranny I think. I would be very thankful for some input regarding a possible cause and if some cleaning or adjustment might repair the problem.
I have had the tranny oil & filter changed about 30,000Km ago.

Thanks,

Sandy

1 Reply

SANDYERIC

MEMBER
2 POSTS

Sandy, you're a Dandy. Does this miss occur when it shifts into overdrive or when it is in overdrive and you are driving along? Is it a kick when it shifts, or a slip where you give it gas and the engine speeds up, but the van does not?

Todays transmissions are mostly electronically shifted as in this Astro and vacuum operated modulator valves are a thing of the past.

Give me more specific information to help you,

Ken[/quote:3093a0f269]

No problems with a shift. Quite frankly I never notice the shift from 3 to "D"rive It's only at higher speeds and if I have it in 3. It acts like a miss on a plug! Little stutters or hesitations. I;m surte it isn't actually the motor as it runs fine in Drive!

Thanks for your reply Ken.

Sandy E