Strange Noises

[BINNCZ71]

Ok.. Fellas need some ideas. This forum always great advice.

My truck through codes for oxygen sensors -front and low catalyst performance. The truck is a 99 Silverado Z-71 ECSB so it has some age and tough miles. Cats started to rattle. OK ... Bad cat. Replace same.

Now it has another creak while in motion. the sound is not coming from the motor, I replaced the u-joints 6-8 months ago.

Tranny was replaced 2 months ago with FLT Level 5.
Need some ideas on what to look for. The truck was out of service for 6 weeks waiting on tranny, the driveshaft was int he ned of truck the whole time, could u-joints again be bad.

The noise does increase with truck speed, then goes away. Comes back at lower speeds, and reverse.

The front U-joint has grease fitting, I greased it today. The rear was a last minute resort with no grease fitting from Advance Auto..

Any thoughts?

Thanks!!!

[GasGuzzler]

Aftermarket cats will always eventually reset P0420/0430. Pull the driveshaft and check the joints.

[BINNCZ71]

I replaced it with a GM Y pipe with low miles from a reputable Junk Yard.

Newer Model, low miles. Replaces the Oxygen Sensors with OEM GM.

Thanks!!

[GasGuzzler]

Cats are the only cause of those DTC's. Everyone else here will tell you to get rid of them and tune the codes out.

[BINNCZ71]

How bad does gutting the cats hurt low end power. I do a lot of stop and go driving. If it won't hurt low end power, I 'm all for it!!!


What all has to be tuned out. I have Hptuners. Just have not looked to see what all has to be done to tune.

[BINNCZ71]

put it on a lift today .. Looks like the clip or bearing is shot in my transfercase.. U-Joints look good. Rotate the driveshaft and hear the same sound, but can feel it pop in the transfercase.