Odd "ticking" sound inside our Trailblazer - any idea's?

[ricoba]

We turned on our 2002 Chev Trailblazer last night and it sounded like a bomb was about ready to go off in the back inside of the vehicle!!!

We snooped around, didn't see anything so drove home. The truck ran fine.

Again this morning the ticking started up again and it goes on then off intermittently.

It's a tick, tick, tick, tick, tick.....it's pretty loud and very noticeable... goes for awhile then stops.

It seems to be coming from the rear inside compartment.

You can't hear it outside and does not appear to be coming from the engine or transmission area.

There's no clock or bomb (or anything else) in the rear compartment at least not one that we can find!

It is one of those really odd things!

Any diagostic service advisors here???

Thanks!

 

[Marvin]

Possible cause

The electric fuel pump may be causing the sound you described. It is not supposed to make a ticking sound, but it is located towards the rear and on the frame of most vehicles.

 

[Topeka Tom]

First Guess! OK, Second Guess

Sounds like perhaps your muffler, or more likely, your catalytic converter, is resting against its heat shield. As they heat up they expand, usually at different rates, so they move over one another in a series of little clicks.

Alternatively, your tailpipe may have shifted so that it clicks as it expands, too, although I would expect a loose tailpipe to make at least a few knocking sounds, too.

I hope you find the bomb before it goes off

 

[ricoba]

Both of those answers make sense and thanks for the help.

The only thing is that you hear it inside the vehicle and only muffled on the exterior????

It is really wierd!!! And if you don't hear from me again, you'll know it detonated

Rick

 

[rsonc]

you might want to look at these 2 sites. I think I remember reading something about that. I also have an 02 trailblazer with 24k miles on it. It has been in the shop a lot in the last several months.

They airbag sensor, 4-wheel drive computer, AB computer, the main computer of the car (I am not sure what it's called but they called it the "brain", the fuel tank had to all be replaced. I am now hearing a whining noise from the instrument panel and I think that will also need to be replaced according to one of the bullents that I read on one of the sites. My check engine light keeps comming on and now my airbag light is comming on and off again. I was lucky so far everything has been covered under the warrenty but since it just ran out I might have to start paying for it. I think when we get it fix we will get rid of it. We had purchased it used last December with 20k miles on it.

I would check out both of these sites.

Susan

http://forums.trailvoy.com/forumdisplay.php?f=7

http://www.autosite.com/content/research/forums/index.cfm/action/Posts/fid/4761

 

[T_R_Oglodyte]

It might be the internal clock that keeps track of how much longer it is until the various new car warranties expire.

From personal experience, I am convinced that every car made by a Detroit automaker has one of those things in it. Of course, sometimes that clock fails as well, and the car starts falling apart before the warranty expires.

 

[Keitht]

The only thing is that you hear it inside the vehicle and only muffled on the exterior????


Rick

That really isn't a great surprise. The vehicle itself acts as a sounding board if anything is touching / knocking and amplifies the sound.
I don't know if you have ever used a tuning fork, but the effect is exactly the same. Strike the fork and you can hear the note, but press the end of the fork onto a wooden surface and you hear it much louder.

 

[NTHC]

I recently experienced the ticking sound in my van. It turns out to be the fan for the heater.....which has decided to blow only cold air. When I move the heat control the ticking sound will get louder or quieter. I can't hear it outside and the rear heat still works.

Just a thought.
cindy

 

[ricoba]

I recently experienced the ticking sound in my van. It turns out to be the fan for the heater.....which has decided to blow only cold air. When I move the heat control the ticking sound will get louder or quieter. I can't hear it outside and the rear heat still works.

Just a thought.
cindy

We probably will take it to the dealer tomorrow, but are starting to think it's the rear fan....at least that's the area the noise seems to be coming from.