Modulator vacuum line

[Old60Driver]

Is it possible to swap out the long metal modulator line going from the intake to the modulator with a regular vacuum line? The existing line is pretty gnarly looking (bent to he**), and is a pain in the rear to work around.

I'm a bit worried about heat softening it up over that long of a distance.

Thoughts?

 

[brooksman9]

I believe it would collapse. I would just replace it myself if I were you. I would think Summit or In-line Tube should have them.

 

[squaredeal91]

On my truck I'm using a rubber fuel hose for temporary. The previous rubber hose got so soft that it wouldn't stay on the nipple anymore. I'm planning to run some brake line out of the way and use rubber at each end Like it should be.

 

[Ricko1966]

You shouldn't use rubber as the modulator line it can suck shut in the middle of the run,trapping vacuum and giving false signal to the modulator. You can get a piece of 3=16 ths steel line from the parts store for about 15 bucks and bend up a new one.

 

[brooksman9]

Chevy / GMC Pick up Transmission Vacuum Lines -1981,1982,1983,1984,1985,1986 - Classic Tube

Chevy / GMC Pick up Transmission Vacuum Lines -1981,1982,1983,1984,1985,1986 - Classic Tube

classictube.com

 

[squaredeal91]

I was just at Napa and got a 3/16 line lol

 

[CheemsK1500]

I’ve had a hard enough time keeping the little rubber boot at the end of the hard line attached to the modulator. I am not even going to entertain the idea of making the whole line out of rubber. Get a cheap harbor freight tubing bender and some new metal line and just do it correctly now to save yourself misery later.

 

[Matt69olds]

Steel line with a couple inches of rubber hose on the ends for the connection.

Todays useless bit of tech: ever wonder why GM put that loop in the modulator line? It’s to prevent condensation from collecting in the modulator. Let me explain.

Imagine a bunch of short trips in cold damp weather. The engine never runs long enough to boil off the condensation that naturally collects in a line. No imagine that water pooling in the modulator, and then freezing. That will lock the modulator valve solid in the case.

Next morning, the driver starts the car. Naturally, the choke is set and the engine is on fast idle. Cold thick trans fluid, fast idle, and a transmission that can no long control line pressure due to the locked valve. You put the transmission in reverse, normal line pressure of 250-300 is now 2 or 3 times that amount. Something has to give. If you’re lucky, it just breaks the piston. If your unlucky, it will break the case.

The little loop is designed to catch condensation before it gets to the modulator. As much as we like to bitch and complain about engineers, there is usually a reason why something is designed the way it is.

 

[Snoots]

I’ve had a hard enough time keeping the little rubber boot at the end of the hard line attached to the modulator.

A Zip-tie can be your friend.

 

[squaredeal91]

A Zip-tie can be your friend.

I love zip ties. I saw a bumper sticker on a car once. Said
"don't worry, I zip tied it " lol

 

[Turbo4whl]

A Zip-tie can be your friend.

I have a sticker, Says something like, "Zip-tie Certified Mechanic"

 

[CheemsK1500]

A Zip-tie can be your friend.

I’ve been running with a worm gear clamp snugged on it. It’s held up so far for the year or two.

 

[squaredeal91]

Was at the Napa again and scored this fir $9.29
There phasing out all there evercraft.

 

[84GMCSierra]

I did the same thing once. Now I'm just trying to figure out where I had the engine end connected after my engine install, lol

 

[PrairieDrifter]

I did the same thing once. Now I'm just trying to figure out where I had the engine end connected after my engine install, lol

Behind the carb. Usually it's the port on the intake that either has a vacuum tree or just a barb or two.