can i bypass the vacuum regulator valve?

[67buickss]

was having problems with vac at the trans and found out that i have 20 vac going into th vacuum regulator valve and around 10 coming out so i cleaned it and nothing changed, i dont have enough right now to buy a new one and was wondering if it will hurt to just bypass the whole thing?

 

[gwag]

I think you can but it will make the trans shift early. I messed with this once but cant really remember it seems like you can swap the lines at the valve & it will accomplish the same thing (bypass) I bet someone who knows for sure will chime in but I know the info can be found here by searching. Thats how I got it before.

 

[SPECIALTYLC]

Sounds like its working if you have 10 psi . Did you try adjusting the valve to change the shifts? If it wasnt needed they wouldnt have put it on.

 

[ida34]

It varies the vacuum based on throttle position. Full vacuum should not be applied until you are at full throttle.

 

[M1009 Fiend]

Yes you can you will shift early but nothing harmful.

The last half my post shows how i did it
lhttp://www.steelsoldiers.com/cucv/44086-need-some-advice.html

 

[gwag]

What is it doing? Mine was shifting late then hard I have replaced the regulator and had it adjusted by an ex gm mechanic with a vac guage and it still shifts late & hard but it seems like when it gets good & warmed up it shifts good I think my next move will be filter & fluid change & then maybe look at the modulator on the trans. Not to hijack the thread but since it could be the same issue any thoughts on this course of action?

 

[notsosanestan]

take it to a trans shop cant cost too much for them to look at it

 

[gwag]

Yea the last time I had that thought it cost me a transmission!

 

[Keith_J]

You have to understand how the transmission is "programmed" to shift using the manifold vacuum of a gasoline engine. And vacuum is inversely proportional to power in normally aspirated gasoline engines.

Most gasoline engines pull 17-19" Hg at idle or when coasting, sometimes more. When the throttle is suddenly depressed, vacuum drops to 0-2" Hg. As engine speed builds, the vacuum increases.

So if you are shifting late, the first thing to check is all the lines for leaks. This includes the big short line off the vacuum pump (rear of engine), the reducing tee and cap (or reducing elbow), then the lines going to the vacuum modulator (by the injection pump) and then the line from the modulator to the steel line on the right cylinder head. Finally, check the rubber line to the transmission.

If you still have late, hard shifting, test the vacuum pump alone, it should pull 22" Hg. The next two are the vacuum modulator by the IP and finally, the transmission modulator.