Trying to Figure Out this Noise before A Cross Country Road Trip

hesterchester

Original poster
Member
Jan 4, 2018
1
Las Cruces, NM
I have a 2002 Trailblazer, LS, 4WD. Been working to keep it in good shape as I really like it and want to keep it as long as possible, even if it becomes a secondary vehicle. I recently replaced all the brakes, inner and outer tie rods, and front and rear sway bar bushings and end-links. In the past year have also replaced motor mounts, thermostat, water pump, fan clutch and ball joints. So I've sank alot of time and money into this car.

It has been making these noises that I'm concerned about for a while. First was a rhythmic ticking that I really only heard when I had my window down at a drive thru where the sound could bounce off the wall. Has been around for a year or two without getting much worse. Just the past couple mornings I've noticed that I am hearing a sound that I believe is different from inside the cab.

On Monday I am driving 1700 miles from New Mexico to North Carolina so I'd love to have some insight on whether or not this is a sound that you would be concerned about. The TB will be following a 22ft moving truck so it shouldn't be going more than 65 or 70.

Here is the link for the sound:
 
Last edited:

Reprise

Lifetime VIP Donor
Supporting Donor
Member
Jul 22, 2015
2,724
The rhythmic ticking (about once every 0.5 seconds, right?) is probably your fan clutch, I'd guess. And it's 'normal' (but very annoying, I'll agree) IIRC, I've heard people say that when you start hearing it, the clutch is on the way out. Mine lasted over a year before I started hearing the 'it's finally gone' noise - most people say it sounds like a jet engine / turbine; to me, it sounded like a commercial truck - like a GMC TopKick, if you're familiar with GM's med. duty commercial trucks.

Anyway, you'll make the trip w/o having to worry about replacing the clutch. Keep an eye on your temp gauge (which isn't a real gauge, but that's another post) If your temp needle stays rock solid, you're fine.

As for the fix, you can go one of two ways.
The 'easy' way is to get a direct replacement (it's an electro-viscous clutch, and it communicates with the PCM.) The problem is that it will eventually fail again.

The better way, IMO (and many others here as well) is to replace it with a thermal clutch, like the pickups use. It's not a 'forever and ever' fix (but it'll easily outlast 2-3 of 'our' E-V clutches, if you get a quality brand, like a Hayden) GM themselves switched to this for the last year or two of the 360s (TB, Envoy, etc)

In order to do this, however, and not throw a trouble code, you have to turn off the fan codes in the PCM. For this, you need someone who has the software (HP Tuners, etc.) There are two members who do this (for a fee) - PCMofNC (sp?), and Lime-Swap (who I used; he only charges $100 for our trucks. If you want to tweak the PCM after that, it's only $25 for the return trip.) Both have 'loaner' PCMs you can rent, if the truck is a daily driver and can't be OOS while your tune is being done.

There are (many) threads on how this is done, other things that will benefit from a tune, etc - you should be able to find them.

As for the other noises, I'll need to let others chime in on those; I have the 5.3, not the 4.2
To my untrained ear, I didn't hear anything 'fatal', etc.

Both engines use the same fan clutch, so I could comment on that at least...



(I can't believe I typed all of this on a smartphone, with a laptop 3ft away...one of my fingers 'went to sleep'...lol)
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
How to test the electro-viscous fan clutch

If it's ticking, it might still be working though. If the ticking went away when you remove the belt. it's likely the clutch. @Reprise 's advice is good. The thermal type you would replace it with is for the 2008-2009 TB. Yeah, this was such a failure, GM dumped the EV clutch, going back to the thermal.
 

Forum Statistics

Threads
23,273
Posts
637,488
Members
18,472
Latest member
MissCrutcher

Members Online