Vac Lines?

[Darin]

I recently installed Adam's vac line kit in truck. Pretty easy, followed the directions, all I had was the basic kit plus cruise line. An interesting thing happens now, when under boost I can feel air on my legs. Sounds odd to me... Could the check valve possibly have been put in backwards, pressurizing the air system somehow and blowing open a vent?

It's too dark to take a look right now, but I think there are usually arrows on the valves, and I would think that the arrow should point to the vac nipple located under the front of the throttle body (the pressure source), correct? Not backwards?

Just making sure before I go try and swap it around.

 

[Gimpster]

Re: Vac Lines?

Does your truck still have the vacuum ball?

 

[Ian Turgeon]

Re: Vac Lines?

If you get a chance in the light, take a look at the check valves. They have one side that is tapered, the other side is flat. The tapered side should be on the side of the vacuum source.

Maybe its a bad valve, maybe its in backwards (unlikely its backwards, the valves we use are not the same size on both sides)

 

[SYO237]

Re: Vac Lines?

What Ian said Darin.... take a look at the valves, they are pretty hard to put in backwards cause of the different end sizings...just wont allow it without some force.

Throw me a PM or get with Ian when you get a chance to look and tell us what you find.

If you get a chance in the light, take a look at the check valves. They have one side that is tapered, the other side is flat. The tapered side should be on the side of the vacuum source.

Maybe its a bad valve, maybe its in backwards (unlikely its backwards, the valves we use are not the same size on both sides)

 

[Darin]

Re: Vac Lines?

Well, the check valve is installed properly and functioning as it should.

What else could this be from? The only pressure source under the dash would be my boost gauge line, and that is installed brand new and in perfect shape. Ideas?

 

[bmwtech]

Re: Vac Lines?

I would bet on the vacuum ball . default for the heating vents is the floor vents when it looses vacuum ie you hit the the throttle it opens the floor vents

 

[Don W.]

Re: Vac Lines?

Where the vac line connects to the HVAC near the dist, pull it with engine running and see if you have vac. That would eliminate a functional valve installed backwards, but not a purely bad valve. Look around above your legs. I think there's a diaphragm nearby. See if its vac line has disconnected. You'll need to fix that regardless.

 

[Darin]

Re: Vac Lines?

Thanks! The heater does work and you can change the vent settings (ie defrost, legs, etc). I'm willing to bet on the lack of the vacuum ball. But then the question arises, how does it lose vacuum then under boost when the check valve is installed correctly and working fine?

I'll look more closely today, I'll have some time after doing the front pads.

 

[Don W.]

Re: Vac Lines?

But then the question arises, how does it lose vacuum then under boost when the check valve is installed correctly and working fine?

Because a) it's not a perfect system so that, b) under boost, there is no vac to replace what is "lost." (All the vac ball does is delay the inevitable or until you let up on it making vac again.)

 

[Darin]

Re: Vac Lines?

Everything looked good an connected under the dash. I'm gonna go with with the lack of a vac ball in my case. I'm very certain it's just moving the heater flow diverters back to the legs.

Lesson Learned! Don't be so bloody paranoid, Darin

Thanks for all the help!

 

[SCWolverine]

Re: Vac Lines?

Au contraire, that paranoia may someday save you from a rebuild. Always better to stop and investigate if something doesn't seem right.