Exhaust noise on start up goes away after engine warms up
2008 GMC Envoy is only equipped with one of two engines:
4.2L (254") 6-Cylinder SFI
5.3L (325") V-8 SFI
Niether of these engines are equipped with an EGR valve, so I guess the probability of that being the cause of your noise is pretty much zero to none.
If you believe the noise is being caused by the exhaust ststem, then the only way to verify that is to inspect the exhaust system. Leaks are easier to verify with the engine running.
With that said, there is also a Technical Service Bulletin (TSB) that is published by GM that addresses customer complaints about loud noise that is being caused by the electro-viscous engine cooling fan clutch. Some people describe it as exhaust noise and others describe it as the engine "racing" or "roaring".(even though the tachometer (if equipped) will be reading normal)
It basicly says that it can make noise on startup due to high rpm of the fan which goes away once the electric solenoids open and allow the fan to start free-wheeling. GM says this is normal operation. You might want to check to be sure this is not what you are hearing. (it can be pretty loud)
SOURCE: 2002 jeep liberty siren whining noise on start up
I had the same problem at about the same mileage. Replaced the power steering pump and the start up screaming went away! ( The Jeep's and mine!)
SOURCE: horrendous noise seem to be coming from engine
sorted the problem there was a bolt missing out from where the exhaust goes into the manifold and there was a gap have sorted it with some gun gum and bandage
SOURCE: loud rattleling noise from engine comapartment
Thank you for responding to my email regarding my car problem. Your suggestion to replace the timing belt/tensioner had nothing to do with it because they have been replaced recently and infact I may have found the problem and please correct me if I am wrong.
Well, I performed a compresion test on the engine and found out that two of the cylinders are only putting out 150psi compare to the other two which is 180psi. I also found out that these two cylinders are not firing even if they are getting fuel into them and receiving spark from the spark plug wires. You can troubleshoot this easily by pulling the spark plug wires one at a time and you should be able to tell a diffirence on the engine idle. If no change on the idle then that cylinder is not firing. Right now my car is parked and I'm rebuilding the enigine myself.
SOURCE: loud whirring noise at start-up
The first thing to check would be to make sure the power steering reservoir is not running near empty, locate the filler cap for the power steering pump it should be marked and then add the appropriate amount making sure you don't over fill, that may make the sound go away if not we must move on to the next possibility, by the way if the noise gets louder when you turn the steering wheel it is most likely the power steering pump or fluid level is low.
SOURCE: experiencing a
it may need a lifter or valve adjustment when cold they will tick or knock depending on how loose or worn out then when it warms up they swell with heast and noise stops. after adjusting or replacing it will stop making noise
1,908 views
Usually answered in minutes!
This noise is very loud but it goes away after driving a block or so. Could it be some kind of valve? EGR maybe?
×