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Discussion Starter · #1 ·
Hello to all GMT enthusiasts out there! I have a 2009 GMC Envoy SLT model I have had for about 6 months now. The truck was great until the water pump pulley started the wobble on me so I went ahead and replaced it no problem. Literally 2 days later the Transmission started slipping on me! I’m pretty handy mechanically inclined no problem but this was out of my league. So, I had it rebuilt and a few days after getting it back I noticed a ticking noise in the driveway. I can only really hear it in the cabin like it’s coming from the firewall center area. After I start it anytime it doesn’t tick until either I touch the gas or start driving. ONLY HEARD AT IDLE INSIDE THE VEHICLE! And not all the time! Transmission shop looked at it twice and said it was not transmission related. All pulleys and fan/ belt are totally quiet up front! I’m losing my mind here I swear it wasn’t making this noise before the trans was rebuilt! Everything runs 100% no leaks no lights on dash it’s just that damn ticking!! Any thoughts please I have searched online everywhere and nothing like this.Thanks to all much appreciated!
 

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2002 chevy trailblazer_lt
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Just for kicks..... fully test out your heater and cooling system.

Check that you can succesfully direct the air to all the optional modes.


You just might have an actuator that broke its plastic gears when it tried to recalibrate as they will whenever they have had their power removed and then reconnected as might happen when someone is removing something like a transmission.

There are 5 actuators in the dash, 3 by the drivers side footwell, o e near then passenger footwell and one more buried way up in the center of the dash.
 

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Discussion Starter · #4 ·
Just for kicks..... fully test out your heater and cooling system.

Check that you can succesfully direct the air to all the optional modes.


You just might have an actuator that broke its plastic gears when it tried to recalibrate as they will whenever they have had their power removed and then reconnected as might happen when someone is removing something like a transmission.

There are 5 actuators in the dash, 3 by the drivers side footwell, o e near then passenger footwell and one more buried way up in the center of the dash.
Just for kicks..... fully test out your heater and cooling system.

Check that you can succesfully direct the air to all the optional modes.


You just might have an actuator that broke its plastic gears when it tried to recalibrate as they will whenever they have had their power removed and then reconnected as might happen when someone is removing something like a transmission.

There are 5 actuators in the dash, 3 by the drivers side footwell, o e near then passenger footwell and one more buried way up in the center of the dash.
[/QUOTE
Just for kicks..... fully test out your heater and cooling system.

Check that you can succesfully direct the air to all the optional modes.


You just might have an actuator that broke its plastic gears when it tried to recalibrate as they will whenever they have had their power removed and then reconnected as might happen when someone is removing something like a transmission.

There are 5 actuators in the dash, 3 by the drivers side footwell, o e near then passenger footwell and one more buried way up in the center of the dash.
Sorry for the confusion it’s difficult to describe the situation and I felt I was a little long winded as it was. I’ll get the Envoy into the garage soon and investigate the actuators and see if I can find any faults. Thanks again
 

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Reporting back on the actuator findings I cycled all the selections and I could clearly hear the actuators cycling to each place. This noise unfortunately isn’t the actuators. Everything worked just fine with the hvac system. The ticking is heard the best from in the cabin but the issue is not inside the vehicle. Possible injector tick??? I have noticed a slump in fuel economy as of lately.
 

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Reporting back on the actuator findings I cycled all the selections and I could clearly hear the actuators cycling to each place. This noise unfortunately isn’t the actuators. Everything worked just fine with the hvac system. The ticking is heard the best from in the cabin but the issue is not inside the vehicle. Possible injector tick??? I have noticed a slump in fuel economy as of lately.
You ain't NEVER gonna hear any of those injectors "click". Move away from that idea now.

Ticking has to be something created, not as a result, really.

A bad cabin air control module is usually the obvious problem. Just FTR --- don't disconnect the battery ever. Never.

"Clicks" should be things like:
Blower fan has something in it
Loose convertor bolt(s)
Too long of a bolt/stud that hits something that is spinning/rotating
Leaky exhaust flange mount -- that can happen when the engine is hung down after removing the transmission --- hmmm?
A loose spark plug --- this is really kinda/should be rare --- but it happens.

Here's an oddball thought after I re-read your post --- a loose Oxygen Sensor --- you said you've been experiencing low fuel mileage -- and these are things that get forgotten or never replaced every 40-50K miles as a tune up part.

Imma leaning toward a leaky exhaust flange gasket here --- it's something that might have been disturbed during a transmission R&R.

I'd like to hear it though --- in a LONG video, loaded up on YT just for this purpose --- no 5-second, shaky camera videos, please ... and talking over the sound ist verboten!
 

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Discussion Starter · #7 ·
You ain't NEVER gonna hear any of those injectors "click". Move away from that idea now.

Ticking has to be something created, not as a result, really.

A bad cabin air control module is usually the obvious problem. Just FTR --- don't disconnect the battery ever. Never.

"Clicks" should be things like:
Blower fan has something in it
Loose convertor bolt(s)
Too long of a bolt/stud that hits something that is spinning/rotating
Leaky exhaust flange mount -- that can happen when the engine is hung down after removing the transmission --- hmmm?
A loose spark plug --- this is really kinda/should be rare --- but it happens.

Here's an oddball thought after I re-read your post --- a loose Oxygen Sensor --- you said you've been experiencing low fuel mileage -- and these are things that get forgotten or never replaced every 40-50K miles as a tune up part.

Imma leaning toward a leaky exhaust flange gasket here --- it's something that might have been disturbed during a transmission R&R.

I'd like to hear it though --- in a LONG video, loaded up on YT just for this purpose --- no 5-second, shaky camera videos, please ... and talking over the sound ist verboten!
Thank you for the detailed reply, seriously you raise a lot of excellent points I did check the exhaust and I literally could wiggle it as it was moving at the triangular plate just off the manifold! Is there supposed to be a dounut in there?? Doesn’t look that way but I don’t feel air leaking until I wiggle it white it’s running! Like it’s air tight til I disturb it.I know they had to drop the exhaust to do the transmission and we know they disconnected the battery too. They say it’s not in the transmission I took it there twice. Also had a broke exhaust hanger and the transmission which they fixed but said I may have hit some snow to knock it off but I never drove it til the roads were clear as we had a storm here in Buffalo at the time. I swear they messed it up no way it was heard before the transmission was done! I’m about done as well .
 

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Discussion Starter · #8 ·
Thank you for the detailed reply, seriously you raise a lot of excellent points I did check the exhaust and I literally could wiggle it as it was moving at the triangular plate just off the manifold! Is there supposed to be a dounut in there?? Doesn’t look that way but I don’t feel air leaking until I wiggle it white it’s running! Like it’s air tight til I disturb it.I know they had to drop the exhaust to do the transmission and we know they disconnected the battery too. They say it’s not in the transmission I took it there twice. Also had a broke exhaust hanger and the transmission which they fixed but said I may have hit some snow to knock it off but I never drove it til the roads were clear as we had a storm here in Buffalo at the time. I swear they messed it up no way it was heard before the transmission was done! I’m about done as well .
On another note I hear the ticking clear as day in the driver seat then pop the hood and listen very carefully I also was poking around with a thin metal tube to feel for vibrations the most I can feel is right under the top plastic cover on the top of the motor. Valve cover down I feel literally no vibrations
 

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Discussion Starter · #9 ·
So I also gave it yet another thorough inspection today with a co - worker . I had him feather the gas while I wiggled the exhaust no change. And we also noticed the ticking noise does not change with engine rpm. It is 100% consistent no matter what select every gear in the transmission every selector on the heater no change . Mostly felt on top of intake cover above spark plugs/coil packs 100% sure that’s the area. Vibrations felt on cover not felt anywhere on engine itself from valve cover down its smooth.
 

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On the driver's side of the engine, about midway from the front and about midway down the block is an EVAP system solenoid. Look and listen there. Heck you might even want to put your hand on it (if it's not too hot) to see if you can feel it clicking at the same time you hear it.

If you do isolate the click to this EVAP solenoid, then report back for further diagnostics to determine if the problem is electrical or a bad solenoid.

Good Luck!
 
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Yup ... follow chem_man's instructions --- I think he's on to something.

The reason why we both now go that way (the culprit might be the ECS Solenoid) is because you never said it was a constant rhythm, never changing with the engine RPM.
THAT was IMPORTANT information.​

THIS is why we need details --- and single-lined questions and responses.

When things are monoparagraphic, we (old guys/bad eyes) cannot find the words that are important - sometimes.

So --- Like I broke up MY sentences (so does chem_man), it's nice if everyone does it too.
 

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Thanks guys I’ll check into that solenoid tomorrow. I’m gonna run with it and report my findings. Good looks guys——much appreciated.
We need this sortta feedback --- it bolsters our ability to figure out the cause if we actually know the effects.
 

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Discussion Starter · #15 ·
Ok, so I put my hand on the solenoid while running and —- I can FEEL IT PULSATING.
The TICKING STILL SOUNDS LIKE IT ABOVE THAT IN THE ENGINE.I wiggled the solenoid just to see but no changes in ticking.
ALSO NOTE, at one point I went from park to drive with my foot on the brake NOT ON THE GAS and switched back from park to drive a few times and the TICKING NOISE WAS LOUDER IN PARK THAN IN DRIVE BY FAR.
 

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OK, now for the diagnostics. Unplug the electrical connector to the solenoid and retest. If the ticking goes away, you have identified the culprit.

NOTE - Because the EVAP solenoid is mounted to the engine, the ticking sound can be transferred to the engine block and it can appear to be coming from something else.

Next comes the question of is the EVAP canister purge valve/solenoid bad? Well, is there a corresponding Diagnostic Trouble Code (DTC) that has been set? If no, then it might just be a noisy solenoid that is functioning normally. If you decide that the noise is driving you nuts, a decent replacement will cost you somewhere between $25 - $60 depending on where you purchase the replacement and brand chosen. Also, if you do replace it, please do not purchase the least expensive one found on Amazon/ebay/etc. as it will likely be a white gox, generic, chinesium low quality part. Purchase one from ACDelco/GM Genuine, Delphi, NAPA Echlin, Standard Motor Products (non T series), or BWD (non P series).

Good Luck!
 
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