sjfehr

Torque is great; it lets you look at raw MAF and O2 sensor data as well, and may help you diagnose what's going on.

ep3_lol

So, the car has continued to run and idle fine and there has been no check engine light. But shortly after I installed the AOS I started to hear a soft whistle on occasion whenever I stepped on the throttle from idle. I checked the AOS connections last night and the lower end of the flexible tube had raised up on the crank case (I think) connector somewhat. There was a trace amount of fresh oil in the area. I cleaned the oil up and readjusted the clamp and hose to the proper position. The sound immediately returned but I haven't been able to check to see if the hose moved again. I've opened and closed the hose clamp several times. While I can't move it at all by hand when it is completely closed, is it possible that it's been weakened and isn't holding the hose down tight enough?

Macster

Having never done an AOS myself I can't help you other than to say maybe.

A hose clamp generally though doesn't weaken, if we're talking about the plain old hose clamps with the screw closure feature unless they are severely overtightened then the screw can strip or the edges in the band openings it works against round off.

What generally happens is the hose clamp is overtightened and damages the material it is clamping.

Often there is a lip on the connection that the hose must extend beyond and the clamp most be positioned behind so the clamp squeezes the hose and forms not only a good seal but in reducing the hose's diameter ensures it can't be pulled (with reasonable pulling force) over the ridge.

Or what the hose connects to (or the hose itself) is not clean and the hose works its way loose or the hose is too short and there's tension and this pulls the hose off over time or the hose develops a crack/split or a tear.

Now a tear/crack or split can be present when the thing is new. It is always a good idea to inspect a new rubber hose or other rubber tube carefully inspected (the fancier the design or the harder the item is to get to and replace the more carefully it needs to be inspected) for any defects before installing it. Just to be sure.

Sorry. Not much help. You are at the car and you will have to go in there again and eliminate the above and any other possible explanations for why the hose comes loose.

Oh, one other thing to consider: Is the AOS the right one for the car?

sjfehr

Check other vacuum tubes in the area; it's possible you knocked something else loose while working on the AOS.

ep3_lol

I'll check other vacuum tubes, didn't think about that. I didn't feel any tears in the hose and didn't see any before it went in. The clamps are the spring type, not the bolt type.

Macster

Those are harder to screw up. But if they are cheap they can lose tension and not clamp with very much pressure. It is like the clamp just has 1 installation in it.

ep3_lol

Just a follow-up as I've gotten a PM regarding this thread. Replacing the AOS resolved the hunting idle and coolant smoke issue completely. Hendrick Porsche confirmed that I got that hose clamped back down right, so that was not the source of the whistling. I still have the whistling noise but have had no other indication that anything is wrong. Woohoo

Macster

Did you leave the oil filler tube cap off?

ep3_lol

Definitely did not. The whistling is very faint and it honestly might just be in my head. Hendrick Porsche actually put the car on one of their lifts and checked the AOS connections and everything checked out.

Macster

That's good. I've done that a time or two though the noise it made was not a whistling but a odd howling/honking noise.

About the whistling noise... does it happen with the car stationary?

Be sure the power steering pump reservoir fluid level is ok.

If the noise appears when the engine is started cold you can remove the serpentine belt and start the engine and confirm if the noise is still present.

Check the belt edges. If one (or both) are sharp this can arise from the belt not tracking properly and this can be from an accessory drive with excessive bearing/shaft play. Then the noise can be from the belt or even the accessory drive.

If the belt edges are ok, then I'm thinking maybe the noise is an early phase of an idler roller bearing failing.

You know, even if the noise only appears when the engine is warmed up you can try to determine say if you leave the engine off an hour and restart it and if the noise is present then you can still remove the belt and start and run the engine a bit, just long enough to confirm the noise is present or not.