Vibration at 1500 RPM
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Vibration at 1500 RPM - 3/22/2008 8:15:06 PM
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finall
Posts: 111
Joined: 7/20/2007
Status: offline
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Mystery tech question. What is it? The person who figures this out is a Genius, and I will bow to them and call them a god on this forum.
What: 07 SUV. 11K Miles.
Problem: Having vibration at 1500 RPM, in drive, under light load (eg. on flat highway.).
Resonance (vibration) sounds like engine growl or exhaust resonance. Makes engine sound rough. Resonance transfers to body and floorpan.
Diagnosis: Happens at any speed, so not speed related.
Therefore RPM related to drive train, as long as RPM is 1500-1600. Higher or lower RPM, no resonance, and engine is smooth. No codes set.
Most of my cruising is done at around 1500 RPM range, so the resonance gets very annoying.
Growl gone if rolling with engine at 1500 RPM and in neutral. So guessing problem is in drivetrain behind engine?
Checked another 07, and sound Hz is in same range. 06 Does not do this.
Are all 07s like that? I know they changed the exhaust on the 07's to 3.5" pipes. It sounds terrible. If within design, still not normal. Makes our 07 a bad driving experience.
Took a 07 H2 Shop Manual and tried to diagnose, but do not understand "orders of vibration", and how to pinpoint source.
Anyone out there with an 07 encounter this?
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RE: Vibration at 1500 RPM - 3/22/2008 11:40:51 PM
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finall
Posts: 111
Joined: 7/20/2007
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Thanks for the info Shortbus. No, everything that I can see from underneath seems tight and straight. The vehicle was never offroaded. The sound is a resonance or growl.
Not a tapping or clanging, or anything hitting metal on metal.
It sounds like it is coming from inside the engine or exhaust. still think something is out of balance or vibrating somehow. Or some kind of pressure resonance in the exhaust.
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RE: Vibration at 1500 RPM - 3/23/2008 1:51:13 AM
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TheGunnyRet
Posts: 307
Joined: 11/21/2007
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As I read this, this only happens when you are moving. And the vibration stops after you reach a certain RPM while moving.
Check your CV joints and look for grease spatter behind the brake assembly around the A-Frame suspension. If there is no grease thats good, but you still can have a CV joint starting to go.
You could have a Bad Wheel Bearing, Jack the vehicle up just enough so the wheel is off the ground (Front only) grab the wheel and push and pull if it clunks just a little the wheel bearings might be bad or just not tightened down correctly to the Hub.
Park the Vehicle and chock the wheels so you don't roll and put the Vehicle in neutral and crawl under the vehicle and find the drive shaft, grab it and see if it moves up and down, then put it in park and then go back and turn it till it stops then see if it just turns a little more with a thud sound, could be bad universal joints at the axle pumpkin.
Could have lost a balance weight of one of your wheels.
Check your strut mounts and shock mounts.
Check your pulleys on the serpitine belts.
Check Power steering fluid.
Check lug nuts, see if there loose.
< Message edited by TheGunnyRet -- 3/23/2008 1:59:44 AM >
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H3Black2007.5
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RE: Vibration at 1500 RPM - 3/23/2008 6:24:32 AM
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Muddydawg75
Posts: 9959
Joined: 3/11/2007
From: South Jersey Shore
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I'm going to go out on a limb here for you....
Climb under your truck and see if you have two or 3 metal bands around your fuel tank....
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"I feel sorry for people who don't drink. When they wake up in the morning, that's as good as they're going to feel all day." --Frank Sinatra
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RE: Vibration at 1500 RPM - 3/23/2008 10:05:39 AM
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finall
Posts: 111
Joined: 7/20/2007
Status: offline
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Thanks guys!
Ok, I am going to crawl under the vehicle once it is dry outside, and look at all this stuff! I will report back here as soon as this is all done.
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RE: Vibration at 1500 RPM - 3/23/2008 11:12:27 AM
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finall
Posts: 111
Joined: 7/20/2007
Status: offline
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On an UP-posted (posted above) suggestion of a very clever Hummer guru (Shortbus), I have now crawled under the vehicle and looked at something specific suggested to me.
The crossover exhaust pipe (going from right side to left side collector) is totally pancaked against the UCP (undercarriage protector). GM tried to pancake the exhaust pipe so it would clear, but failed. I had to drop the back of the UCP bolts by 1/2" before the exhaust cleared.
The rub point has filed down the UCP at the contact point and exhaust pipe also. If this was left alone, it would have eventually made a hole in the stock exhaust and UCP!
Lots of loose metal rust filings in the area, so it was easy to spot. I could not even slip 1 piece of paper between the two pieces of metal. Could this be the problem?
I easily removed the UCP (3 bolts) by loosening the front skid plate (5 bolts), and will go for a test drive later today.
I do not know if this problem is related, but it is a problem that needs to be fixed. Off to the dealer to bend the exhaust. If it is the solution, it will be a very easy and fast fix.
< Message edited by finall -- 3/23/2008 7:13:21 PM >
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RE: Vibration at 1500 RPM - 3/23/2008 1:32:02 PM
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TheGunnyRet
Posts: 307
Joined: 11/21/2007
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quote:
ORIGINAL: shortbus
unposted suggestion? damn, glad i could be of absolutely no use to you. good luck getting the exhaust pipe bent, it would be much easier to simply add some washers between the frame and UCP to move the cage down. but what do i know, i'm obviously no help whatsoever.
quote:
ORIGINAL: shortbus
did you check your transmission undercarriage protection to see if it's hitting the exhaust pipe where it crosses over to go into the muffler?
Good Call shortbus, You are a Genius, GURU, The Man. I guess I was completely off base.
_____________________________
H3Black2007.5
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RE: Vibration at 1500 RPM - 3/23/2008 4:40:21 PM
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finall
Posts: 111
Joined: 7/20/2007
Status: offline
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Ok, I officially declare "Shorbus" a Hummer Guru God, and I humbly bow to him here! He got it immediately!
(Oops, Sorry Shorbus about the last post above, I typod it to death, and now edited it to reflect your seriously H2 Genius status. ) Did not mean to offend, jsut a typo. I meant to say up-posted, not unposted. My mistake. Also, I missed the contact point the first time around. Since the vehicle was never offroaded, and the UCP was not bent, the contact point went unnoticed. The problem is solved!!!!! I love my Hummer again~!
The big local Hummer Dealer could not figure this problem out. They said there was nothing wrong.
I was starting to hate my rig because it was vibrating me to death. I could feel it in my teeth.
It was in fact the droning from the exhaust, that transfered to the UCP, and then to the rest of the vehicle. Took the UCP off. Just came back from a 60 mile run, and NO MORE vibrating growl NOISE!
I bet every 2007 H2 has this problem, since my exhaust was 1/2" too low in that spot, and that is a lot. I bet they do not have that much tolerance during production.
So off to the dealer to repair this HUGE defect. I would be surprised if there was not a TSB on it.
In fact, does anyone know about a TSB on this that I could take to the dealer?
The other brand new 07 I took for a spin odd the Dealer's lot to compare definitely has the same problem. I am glad I did not give up and assume that there was no problem, and that they all sounded like that.
Thanks to great help from great guys like "Shortbus", weird problems like this get diagnosed and fixed. And YES, I will suggest to the dealer to shim the UCP and use longer bolts. Since further bending an already pancaked cross-over pipe another 1/2" is just asking for lots of trouble.
I love my Hummer again~!
< Message edited by finall -- 3/23/2008 7:17:18 PM >
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