I'm not the biggest guru when it comes to vacuum lines. This weekend I installed new Samco hoses and a Python hose lock kit. After installing the lock kit, I noticed hissing noises after I shut the engine off. Another thing I noticed was when I'd rev the engine to 3k then let off the accelerator, the car would putter as it returned to idle condition. First thing that came to mind was a vacuum leak in one of the lines.

I remembered when I removed the hose(blue arrow), it was under pressure and I released the pressure when I dettached it. With that being said, to remedy the idle problem I removed it again. Sure enough, there was no pressure in it this time. I refastened the hose and tightened the hose locks with the supplied wrench this time. I had previously only hand tightened them. This fixed the ilde problem.

My 1st question is: What is that hose for and what function does the vacuum provide?

Next problem. The picture with the yellow arrow . The tube I installed the hose lock on is for the PCV. The kit only comes with 1 fitting for this hose. The other side of the hose goes into the plenum, which is under the cover. I figured, why install it on the side of the hose that's under the cover if it's not visible. Instead, I installed it on the other end that attaches directly to the PCV. When I shut the engine off, I hear a high pitched hissing noise coming from this area. I figured that the hose lock needed to be tightened down more, so I did but the noise is still there. BTW, the car runs fine.

Did I install the hose lock on the correct side of this tube?
Is the hissing noise normal or is there some type of vacuum that should be present at the valve?

Thanks guys,
Val

 

Val - those connections look fine. The hose that runs from the plenum to the battery box just draws the vapors out that escape from the battery (hydrogen). Everything connected to the plenum is operating under a vacuum.

 

Gotcha Should I still be hearing a hissing noise from the PCV connection when I shut the engine off? It sounds like air escaping from a balloon if you stretch the ends of the balloon mouth to create a narrow exit, although not as loud but still similar to the high pitched squeal.

 

Are those the OEM hoses or the Samco replacments? I though I had heard/read at one time that the Samco's were a little larger than OEM. It could be that you're not getting a tight seal and that's the leak you're hearing. Normally, I don't think you should be hearing any leaks.

 

I think I know the noise you're talking about. Is it a mix between a hissing and whistle when you turn the car off? I'm thinking I have a vacuum leak too

 

What? Is this for real?

That hose is for the brake booster.

 

Those 2 hoses are OEM.

 

+1..It's hissing and whistling. I don't think it's normal either, but not sure. It's one of those things that you really never pay attention to until you're actually working on the component. I could put the old hose clamp back on, but it would defeat the purpose of buying the hose lock kit. I did notice the hose itself was really hard and not very flexable, compared to the others. The hose clamps pushes into the 90 degree bent part of the hose, making it hard to slide the hose into the hose clamp. I might just go to the autoparts store and pick up some bendable heater hose, to see how it functions.

 

Actually that's the brake booster, make sure that one's not leaking or you may not be stopping so fast!

 

Yeah, I have the same noise and I have no idea where its coming from. My buddy has a stock Z so I may have to meet up with him to see if his makes the same noise.

He's actually the person that pointed the noise out to me a while back

 

Actually the hose on the left is not only the booster hose as Failsafe306 said, it has a check valve in it to keep vacuum on the booster during low vacuum or for one brake push if the engine dies.

Chris

 

The instructions on the hose lock kit identify that some OEM hoses may have a slightly too small diameter for the hose lock. Adjustments should be made by adding tape of some sort to increase the diameter. At 1st, I used aircraft tape, but it was too bulk and not so smooth. As a result, the hose clamp had a hard time sliding over it and ended up peeling back the tape. I guess this made a poor seal. I removed the old aircraft tape and just used plain electrical tape. This made a much smoother evened out surface. Of course using the wrenches this time instead of the old kung-fu, grip to tighten up the hose locks, made a difference also. The only hose I had to hand tighten was the upper heater hose. There is just no way to get one of those wrenches in there to turn it.

 

Let me know what the outcome is.

Last night I took it for a test drive. I don't know if I'm just being optimistic, but the engine seemed to run alot smoother than prior. At idle, sitting in the drive-way, my neighbor even commented on how quiet the engine was. When I shut the car off now, it's completely smooth. Previously it use to have a bit of a murmur/quiver as I shut it down. Honestly I don't see any corilation between coolant/hose upgrades and engine smoothness. But hey, I guess anythings possible

 

westpak is right.....this might be the most important vacuum line on your motor!!!

 

I made sure to tighten that bad boy down real tight...