Inliners International Forums General Discussion Vortec 4200 02 Envoy valvetrain noise

I want to assume this is in the valvetrain....I cannot tell if it's a lash adjuster or maybe a cam phaser.

Sometimes I will get a good loud tap when started cold, but the odd thing is if I shut the motor off and immediately restart it, the noise is gone.

If I plug the top port on the valve cover for about 15 sec, the tapping stops.

Thia noise has been ongoing with varying intensities for over a year, never really has gotten worse. If I shut down one cylinder at a time, no change.

The noise is much quieter after about 10-15 miles of driving, also of I just momentarily tap the gas when idling, the noise goes away at the moment of touching the gas pedal...which is why I thought it could be a cam phaser or maybe even an injector.

All input and criticism appreciated.

I don’t think I’ve ever heard of a Vortec 4200 that didn’t have a little upper end noise. These engine are known to have some sludge issues on higher mileage models. My guess is there’s some sludge in your PCV system. Taking the valve cover off and cleaning may help, again it may not. The tube going to the lower part of the intake gets plugged up too. You may just end up making a mess.

I had a ticking in my 04 that was driving me nuts. I thought it was the fan clutch after replacing, didn’t help. Take 2, it ended up being the water pump had a worn bushing.

Anyhow, sorry for getting off topic, if it’s running good and nothing obviously wrong, I would just drive it.

Chris

Thanks Chris.....I had the valve cover off about 80K miles ago and it was pretty clean. I was using an oil catch can and was working fine until I noticed a reduced amount of oil after 4K miles. Went another oil change and very little was in the can. Turns out there was a small screen in the lid aside from the accumulating mesh and it clogged up.

I managed to clean the vacuum ports and restore PCV operation. The noise in the top has been reduced now but I believe I have something going on with #4.

I used a stethoscope on the #4 coil bolt and could hear a light knock but not that deep sounding. This knock went away when I disabled the #4 coil.

I would like to pull the pan and possibly replace the rod bearings...at least see what's going on.

The motor has 287K miles and really runs smooth and strong, compression is real good for the mileage, Number 4&5 have 190 PSI and the rest have 205-208 psi.

If I go with rod bearings, would OE GM bearings be a good choice or should I look elsewhere?

Sounds like you're well ahead of things. Anyhow, OE bearings? Well, you got 280k out of the first set...

I had a loud top end knock. Change to delo 15w40 diesel oil and it went away. Thats all I run in it now.