Where to begin.....

Over the last couple of weeks I have had multiple issues with my Truck. It is an 03 Trailblazer EXT.

All at once there was a rattling noise coming from near the fan. I noticed my fan was a little shaky as well. I heard this noise before about 2 years ago and after having my mechanic replace all kinds of parts with no fix, a friend of mine pointed out it sounded like the waterpump to him. Replaced it and it corrected it but alas it is back again.

Also we have been hearing what appears to be a humming, whispy noise if that makes sense. It almost sounds as if there is air trying to escape but it cant. When you push on the gas it sounds like it is reving up high but the RPMS are not high.

I took it to my friends house today and he took it out with me for a test drive. He said it was a strange noise he has never heard before and felt like it was coming from the middle of the car. As we were pulling into his driveway all of a sudden a loud pop and squeal. My car coasted into his driveway. My waterpump exploded and the belt shredded. We replaced the belt, the thermostat, and the waterpump. Hoping just maybe the noise was from the belt! Unfortunately it wasnt. Now that the rattling is gone, the humming whispy sound is still there. He said my truck appears to be running hot as well. While under the truck checking for anything loose he just found it extremely hot. He also said I have some oil leaking from my axle and my caliber is bad on one side. But he doesnt feel this is the issue. He said my hub bearing seems fine too with no play at all. He thought maybe my 4 wheel drive was engaged and stuck and put my car up and pressed the gas. The rear tires moved but the front did not. Now he noticed what appears to be EXTREMELY HOT air coming from my exhaust and it is also sputtering out. So now he is thinking possible a clogged CAT or bad muffler? Any ideas what is happening here? He is going to attempt to take it apart tomorrow to see if it runs better without the CAT. Any other suggestions? It is a little sluggish as well in most gears but mainly from 1st to second.

Over the last couple of weeks I have had multiple issues with my Truck. It is an 03 Trailblazer EXT.

All at once there was a rattling noise coming from near the fan. I noticed my fan was a little shaky as well. I heard this noise before about 2 years ago and after having my mechanic replace all kinds of parts with no fix, a friend of mine pointed out it sounded like the waterpump to him. Replaced it and it corrected it but alas it is back again.

Also we have been hearing what appears to be a humming, whispy noise if that makes sense. It almost sounds as if there is air trying to escape but it cant. When you push on the gas it sounds like it is reving up high but the RPMS are not high.

I took it to my friends house today and he took it out with me for a test drive. He said it was a strange noise he has never heard before and felt like it was coming from the middle of the car. As we were pulling into his driveway all of a sudden a loud pop and squeal. My car coasted into his driveway. My waterpump exploded and the belt shredded. We replaced the belt, the thermostat, and the waterpump. Hoping just maybe the noise was from the belt! Unfortunately it wasnt. Now that the rattling is gone, the humming whispy sound is still there. He said my truck appears to be running hot as well. While under the truck checking for anything loose he just found it extremely hot. He also said I have some oil leaking from my axle and my caliber is bad on one side. But he doesnt feel this is the issue. He said my hub bearing seems fine too with no play at all. He thought maybe my 4 wheel drive was engaged and stuck and put my car up and pressed the gas. The rear tires moved but the front did not. Now he noticed what appears to be EXTREMELY HOT air coming from my exhaust and it is also sputtering out. So now he is thinking possible a clogged CAT or bad muffler? Any ideas what is happening here? He is going to attempt to take it apart tomorrow to see if it runs better without the CAT. Any other suggestions? It is a little sluggish as well in most gears but mainly from 1st to second.

A bad cat or restricted exhaust and many other problems can be checked with a Vacuum gauge reading on engine vacuum.
for more help.
Post back engine vacuum reading at idle and at 2K rpm.

If vacuum is less at 2K rpm than idle you have a restricted exhaust system.

Low vacuum or floping gauge needle tells you other problems.

He is going to get a gauge and check what you have mentioned with the vaccumn.

Now today the engine light came on...new issues! It is on steady and when you get over 25 MPH the light goes from steady to blinking. Took it to the shop and it pulled up codes for Cylinder 1 misfire and coolant fan speed sensor.

Another friend of mine is saying he believes this is the screaming noise we are hearing when driving.

He is going to get a gauge and check what you have mentioned with the vaccumn.

Now today the engine light came on...new issues! It is on steady and when you get over 25 MPH the light goes from steady to blinking. Took it to the shop and it pulled up codes for Cylinder 1 misfire and coolant fan speed sensor.

Another friend of mine is saying he believes this is the screaming noise we are hearing when driving.

What are the code no?

I have no clue what the code numbers were as he has my truck at his place. He said the codes were for the misfire cylinder 1 and the cooler sensor. We replaced the fan clutch and the noise is gone! The coil pack appears to be the culprit for the misfire. He should be replacing those out tomorrow as well as the calipers.

I have no clue what the code numbers were as he has my truck at his place. He said the codes were for the misfire cylinder 1 and the cooler sensor. We replaced the fan clutch and the noise is gone! The coil pack appears to be the culprit for the misfire. He should be replacing those out tomorrow as well as the calipers.
Many different code no.
With out code no we can not help.
Let us know how it goes.

Many different code no.
With out code no we can not help.
Let us know how it goes.

Well after changing the coil pack in cylinder 1 and 5 of the 6 spark plugs ( 1 is stuck and we will have to take it somewhere to see if they can remove it), we disconnected the battery to reset the codes. Started her up and after a couple of minutes the check engine light came back on. Drove it down the road and after we hit 35mph the check engine light blinked again. When we come to a stop it stops blinking and again starts again when we hit 35mph. I am going to take it tomorrow to have the codes read again.

Now I do not hear the LOUD sound like I did before but I can still hear a faint sound similar to the loud sound.

Could a bad CAT cause the engine light to blink? I noticed it hesitates alot when going into 2nd gear.

Well after changing the coil pack in cylinder 1 and 5 of the 6 spark plugs ( 1 is stuck and we will have to take it somewhere to see if they can remove it), we disconnected the battery to reset the codes. Started her up and after a couple of minutes the check engine light came back on. Drove it down the road and after we hit 35mph the check engine light blinked again. When we come to a stop it stops blinking and again starts again when we hit 35mph. I am going to take it tomorrow to have the codes read again.

Now I do not hear the LOUD sound like I did before but I can still hear a faint sound similar to the loud sound.

Could a bad CAT cause the engine light to blink? I noticed it hesitates alot when going into 2nd gear.

Light blinking is a misfire detected.

That needs to be fixed first.

After misfire fixed you can use a vacuum gauge to check engine vacuum for restricted exhaust and other problems.

Less engine vacuum at 2K RPM over idle is restricted exhaust.

Light blinking is a misfire detected.

That needs to be fixed first.

After misfire fixed you can use a vacuum gauge to check engine vacuum for restricted exhaust and other problems.

Less engine vacuum at 2K RPM over idle is restricted exhaust.

The only code showing up now is P0303 which is they said is a misfire on Cylinder 3. We had a misfire on Cylinder 1 which we fixed last night. Why now would cylinder 3 go now? Is it common for them to all start going at once?

The only code showing up now is P0303 which is they said is a misfire on Cylinder 3. We had a misfire on Cylinder 1 which we fixed last night. Why now would cylinder 3 go now? Is it common for them to all start going at once?

Not real common but they are all the same age and out of the same batch and have fires the same no of times.
Check the sapar and.
If no 3 coil is not sparking replace it.
Let us know how that goes.

Thanks. I will be going back over to his house tonight to have him replace the coil pack. What is to say the rest dont follow suit! Ughh I have already put in 1k this week in parts and labor. Not what I expected when I made that last payment online last week!

Well replaced the Coil pack in cylinder 3 and so far so good. I purchased a code reader as well and so far everything has checked out fine. Now that the truck is running better we went for a test ride so I could have him hear the noise. He said it is my tires!?!?! I replaced all the tires about 2 1/2 months ago. This noise started about 1 month ago. He said the tires are off road and the noise is definately coming from them. Now that he mentions it, it does sound like a truck with big offroad tires but why would it only start 1 1/2 months after they were initially installed???? I am doubtful but he swears by it! Your thoughts?

Well replaced the Coil pack in cylinder 3 and so far so good. I purchased a code reader as well and so far everything has checked out fine. Now that the truck is running better we went for a test ride so I could have him hear the noise. He said it is my tires!?!?! I replaced all the tires about 2 1/2 months ago. This noise started about 1 month ago. He said the tires are off road and the noise is definately coming from them. Now that he mentions it, it does sound like a truck with big offroad tires but why would it only start 1 1/2 months after they were initially installed???? I am doubtful but he swears by it! Your thoughts?

Big off the road tires do not do good for highway driving.
And lot of the time hard on supension parts and steering.

Look at the thread and see if any uneven wear.

Big off the road tires do not do good for highway driving.
And lot of the time hard on supension parts and steering.

Look at the thread and see if any uneven wear.


I dont know alot about trucks, cars, tires, etc but to me it just does not seem like the tires. I purchased the tires from PepBoys and did not ask for any big off road tires, just regular tires. They are Definity and it was to replace the original size that was on there already.

The noise doesnt start until you hit 30mph and you can feel a vibration in the steering wheel. My husband also said it sounds as if the motor is racing and straining if that makes sense. It is shifting well.

I noticed this morning that the Automatic Shifter seemed loose and actually got stuck in neutral? I wiggled it a bit and then it went back into park. I am wondering if this is all tied together.

I dont know alot about trucks, cars, tires, etc but to me it just does not seem like the tires. I purchased the tires from PepBoys and did not ask for any big off road tires, just regular tires. They are Definity and it was to replace the original size that was on there already.

The noise doesnt start until you hit 30mph and you can feel a vibration in the steering wheel. My husband also said it sounds as if the motor is racing and straining if that makes sense. It is shifting well.

I noticed this morning that the Automatic Shifter seemed loose and actually got stuck in neutral? I wiggled it a bit and then it went back into park. I am wondering if this is all tied together.
Does noise increase with mph?
Going straight down the road at 30-40 mph turn the stering a little right or left and see if noise changes.
If so you have a bad wheel bearing.

No we really did not hear a change in the noise when we turned the wheel while driving. How far do we have to turn the wheel?

I took my daughters car to have new tires put on today and asked the tire tech what could be causing that noise 1 1/2 months after having the tires installed. He is saying we could have thrown a radial belt or a bubble in the tires? Gonna hopefully take it tomorrow to Pep Boys to have them look at it. If they cannot determine the noise then it is going to another mechanic on Monday.

No we really did not hear a change in the noise when we turned the wheel while driving. How far do we have to turn the wheel?

I took my daughters car to have new tires put on today and asked the tire tech what could be causing that noise 1 1/2 months after having the tires installed. He is saying we could have thrown a radial belt or a bubble in the tires? Gonna hopefully take it tomorrow to Pep Boys to have them look at it. If they cannot determine the noise then it is going to another mechanic on Monday.

Just a little bit of a turn will change the noise if a wheel bearing.
Good Luck at pep boys.
Also here is a link for checking for rear end noise.
http://www.differentials.com/install.html


Let us know how it goes.

No luck at PepBoys. 3 of their mechanics checked it out and have no clue what the noise is. The hub bearings they said were fine. I really am frustrated with this. so far a total of 5 mechanics have looked at it and have no clue.

I can think of two things, one of which was already suggested.

1) Partially plugged catalytic converter. Too much restriction causes back pressure that the engine has to overcome or simply cannot, leading to the sluggish or strained performance when at speed. This may not necessarily set off the check engine light, but if it did it may be a misfire or indicate a problem with one of the oxygen sensor readings (not necessarily a bad sensor, just an abnormal reading).

2) Something up with the transmission and/or transfer case (if you have the 4wd option). Have the fluids in both been checked or changed recently?

Low fluid or old, burned tranny fluid can really affect performance. Do a quick dipstick test after it is warm. Is it low? Does it look gray or brownish? Is it cloudy? Does it smell burned? Any one of these conditions indicate old fluid. If so, have them do a regular fluid and filter change...DO NOT PERFORM A POWER FLUSH, ESPECIALLY WHEN NEGLECT IS THE REASON. Run it about a hundred miles, then drain & fill again (leave the filter). Repeat once again. After the thrid drain & fill, the fluid should be completely exchanged.

For 4wds, have the transfer case fluid checked also...this requires getting underneath the truck and doing a finger dip into the fill hole. It should be very blue. If not (very pale blue or gray), have it replaced ONLY with GM AutoTrak II fluid. If the shop doesn't have it, go elsewhere or buy some at the dealer and take it with you for them to change...should take 2 qts, but some places have a minimum buy amount. I get 3 qts to be safe in case of spillage.

Hope this helps!

Thanks! I will have my friend definately look at that! Hopefully today or tomorrow.

The Transmission Oil is brown and does have a burnt smell to it. I will be taking it to have it changed asap.

So I just called Pep Boys to see if they would do a transmission oil change and how much. They said they would not recommend it especially since it is brown and burnt smelling? They said it could make it worse?

replaced both Hubs...noise is gone!

FYI...We did the HUB test. There was no play when we rocked the tire and when turning the wheel no change, but replacing them took the roaring noise away.