Modulator Valves on Automatic Transmissions

[amdforever2]

I've got this Buick that has a transmission issue. When you start it in the morning, it runs fine..........for about a half a mile, then it loses grip of the gear, and you must stop, turn off the car, wait 30 seconds, turn it back on, and you get another half mile, all in first gear. The car never shifts into second.

Now, I've got this crazy neighbor who lives on the first floor and goes out to his car to smoke at 3 am. I just got home and he told me the "modulator valve" is causing pressure issues, and when I turn off the car, that's letting pressure build back up and gaining me my next half mile.

The guy seems nuts the way he acts.......but is could he be right? Is there any such thing as a modulator valve?

 

[Pepsi90919]

yeah, on the front of the 4T60 and early 4T60-E transmissions there's this spherical type device on the front that connects to a vacuum line. that's what the modulator valve is.

doesn't sound like that's the problem. if it went, then your tranny would just shift extra super hard.

 

[amdforever2]

If there is no or miniscule vacuum pressure can it be possible for the transmission to not shift at all?

 

[Pepsi90919]

if there's no vacuum you forgot to start the engine 🙂

i would be looking at transmission fluid and other things like that...

 

[amdforever2]

I put 3 qts of transmission fluid in it tonight.

No change in behavior.

 

[Zenmervolt]

Originally posted by: Pepsi90919
if there's no vacuum you forgot to start the engine 🙂

i would be looking at transmission fluid and other things like that...

I've had zero vacuum to accessories with an engine that was running. All you need is a leak in the lines coming from the vacuum accumulator.

That said, his problem is almost certainly not the modulator valve. Sounds more like a problem with one of the hydraulic shift valves in the transmission.

ZV

 

[Zenmervolt]

Originally posted by: amdforever2
I put 3 qts of transmission fluid in it tonight.

No change in behavior.

Um... If it took 3 quarts to hit the full line and you have been driving it, the damage is already done and you're screwed.

ZV

 

[amdforever2]

So, still looking at transmission rebuild?

No quick fix?