Last night while I was driving, a new noise came up in my '88 GXL. Over 3500 rpm (and very noticable by 4000+), I can hear a hissing noise coming from what sounds like behind the gauge cluster. It sounds like a vacuum leak or air escaping from a hose of sorts; very smooth and non-mechanical. In addition, the warning buzzer for the tach is now going off between 5.5 and 6K instead of at 7K.

Just to clarify, the hiss is entirely not speed related; it becomes audible around 3500 rpms even in neutral. Any ideas?

 

probably a vacuum leak near the back of the motor, do a visual inspection of the vacuum lines.

 

is the little white plastic peice on the back of the engine that has 2 vac hoses off it going down, supposed to hiss? Mine does ...and I never remembered it doing it with my first engine. .... It seems that the little white *** at the end of the white things can turn freely (but never unscrew) so I think this is normal? Or maybe I got some vac hoses on backwards?

 

it could hiss at times but not all of the time, it is a vent and should move semi freely without the cap coming off.

 

hmmm mine hisses 24/7 even idle. Do I got something wrong? What is it?

 

if the lines are on backwards, it will hiss all the time

 

Ok I swithed the lines, and now the hissing is gone, but my exhaust got HELLA quiet, and the car is bucking hard again (like the TPS is set wrong) but it isnt, 1 ohm @ rest 4.55 at WOT.

Arg, I dont know what im going to do with this car.

 

How confident are you that it's coming from the gauge area and not the engine bay? If that's some sort of electrical short going on in the gauge area, Icemark may be of assistance, but I don't know of anything in there that cuts in at 3500. I'll give the wiring diagram a quick look to see if anything pops out at me.

 

What is that white thing and what does it do? what are the two lines connected to?? I feel like I need to make sure the 3 lines coming off the UIM are right.. hehe ... (Scared)

 

Both problems disappeared two days later. The hissing is gone, and the buzzer has returned to where it belongs. I'm fairly confident it was coming from something on the human side of the firewall, as there wasn't any noise from the back of the engine. The source seemed very focused in or behind the cluster as well; if it came from the engine bay, it would have so much dense material to go through and around that it would have been a lot more omnidirectional.

Whatever it was, it didn't sound uneven like an electrical short, or sharp and harsh like a vacuum leak. It was almost exactly like a person making a soft "s" sound between their teeth.

Yeah, how many of you just tried to make the noise? It's like telling you not to visualize a pink horse. Either way, it was like that, and definitely not my imagination. It was loud enough to annoy me over my music. While it's nice things are back to normal, I've never been at ease with problems that fix themselves before being figured out. It means they can always come back, or are still there, just without the symptom.

 

any one?

 

I did.

 

i had the same problem and i brought it in to be looked at... as it turns out it was a vacuum issue... it isnt behind the gauge cluster... trust me. if you think hard about it, what kind of high pressure hose is behind the dash that would produce such a strong hiss? none. it is in the engine bay. it is not a major issue, but it does need tending to....