1999 deville noise problem

[maeng9981]

Hi. I own a 99 deville with 4.6 northstar. I have been having this noise problem since 2008. It makes some rattling(like grinding something, grrrrr..., hard to describe in words) noise only near 1400rpm. Idling and cruising with high rpm is fine.
I got the head gasket changed 6 month ago. I did the code check yesterday and got no codes.
The auto shop near my house tried to catch the noise. Every time they try to fix it, the noise was gone for just a day. After failing several attempts, they refused to try it again because their last solution is over $2000, and it gives me 50% chance.
So I tried to find the origin of the noise by myself. I couldn't hear noise outside of the vehicle, but guessing that it is made near EGR valve.
Oh also I could feel the vibration on the gas pedal through my foot when it makes noise.
ANY possible reasons will be appreciated.

Thank you
Harry

[Pat Appleson]

Hi,
I've got a LF wheel bearing that's bad. It does the same thing. But if you turn to the right the noise clears up.

pat

[submariner409]

Remove the stamped metal cover over the water pump drive pulley and tensioner arm (At the driver's end of the front cam cover, intake cam). Use a socket wrench handle or breaker bar in the square hole in the tensioner arm and relieve the tension and slip the drive belt off the water pump and tensioner pulleys. Spin each by hand. Any roughness or noise is cause for concern.

The vibration in the gas pedal may also take your search to a missing or broken exhaust system hanger cookie. There are two in front, near the catalytic converter, and two in back, at each muffler outlet. A missing/broken hanger allows the exhaust system to contact body metal and vibrate at odd frequencies.

[maeng9981]

Thank you. I'll check and try all of those.

[Blainers]

Maybe I'm retarded bit im new to cadillac forums.. just registered today, and i have some questions about my 99 cadillac. Can anyone tell me how to post a question in the forums.. i cannot find a link to it

[Chadillac182]

Have you checked the valve itself? I had a weird grinding, rattling issue with mine... It was the valve itself making the sound. Right at the back right side of the motor - behind the coils.

[Chadillac182]

OH and Blainers - I'm a noob too... you might be a bit retarded not sure, but, check the top left corner of the main page - It says New Thread - click on it and away you go.

-Chad.

[Ranger]

Just be sure to post your question in the proper forum.

[maeng9981]

Originally Posted by Chadillac182

Have you checked the valve itself? I had a weird grinding, rattling issue with mine... It was the valve itself making the sound. Right at the back right side of the motor - behind the coils.

I once tried to remove the valve but I couldn't make the fuel line out of the way. Maybe there are some other ways.

[Ranger]

Nope, you have to lift the fuel rail.

[maeng9981]

Is it safe to drive without EGR valve for a while? (like 5 minutes)

I want to make sure that the valve is making noise, before buy a new one.

[Ranger]

No. Start the engine with the valve off and you'll see why. You will essentially have a BIG hole in the exhaust manifold (or very close to it).

[maeng9981]

wow, doesn't even run without an EGR valve. Now how can I check if the EGR valve is making noise?

[maeng9981]

Oh wait, I found a new fact. While idling with the a/c on, the a/c compressor starts to work, with making the same noise continuously. This time the noise is not that noisy like when accelerating. When the compressor goes off, the noise disappears.

I just found it because today's weather was hot enough to turn on the a/c.
the a/c works fine.

[maeng9981]

Oh also, it makes noise while acclerating whether the a/c is turned on or not.