Well when i had to replace my starter on my 05 Colorado i had to remove the manifold to gain access. I did not touch the alternator and serpentine belt to get this done though. You will have to remove the wheel well cover to gain access to the a few of the bolts underneath the manifold. What really helped me out a lot was some swivel sockets like these and some extensions. As for the battery and battery box i removed them just get to a better angle on some of the bolts.

This guide here talks about removing the manifold among a few other things. Look for the section that says Intake Manifold removal, that should give you an idea of some of the steps you will have to follow in order to get the job. Carefull with the plastic clips that hold the wire loom and fuel lines as they tend to be brittle from age and break very easily. Best of luck

 

Thanks. I'll look this over. Doesn't seem like a fun project though.

 

When I messed with my manifold 5 of the 7 or so bolts were loose so that may be your issue. Several members have found there's to be loose as well.

 

Did you red loctite them and retorque?

 

As it turned out, all the bolts were totally loose. Tightened all of them up and truck runs great now. We'll see if that is the final fix.

 

Another member with loose manifold bolts. Im glad the ended up being the issue. Free and doesnt take forever.

 

@1ArmBandit and @zexy majician , I'd recommend you guys check your manifold bolts also so that can be eliminated as a possible cause for those missfires.

 

When I did my valve cover and intake gaskets......... 5 out 9 were finger tight at best.

If you remove the intake manifold.......remove the stupid fucking cover and foam insulation ....... it took me 15 minutes to reinstall the intake manifold with the gained visibility and clearances

 

If your just checking/tightening bolts, should be able to only remove battery and box. Part of the process to remove the intake manifold is to remove driver's tire and wheel well cover, but that's only so you can get to the bottom bolt to remove the alternator. Might be able to get to the first manifold bolt behind the alternator using a universal joint and playing with different lengths of socket extensions.

 

Could the bolts loosening up cause a vibration?

Although mainly when cold, my truck has developed a rather prominent vibration between 1100 and 1500rpm from the drivers side. I've also noticed my idle has dropped lower than usual which is also causing a vibration.

 

@Sync

They could, but if the bolts were that loose, you'd probably have a CEL from a misfire.

I'd also recommend taking a look at the motor mounts

 

There's a metal plate that bolts between the manifold and the engine block, that the oil dipstick and fuel lines attach to, as well as a bunch of the wiring harness. That itself is a PITA to get out of the way to get at the manifold bolts. I removed the plate and never put it back - with the wheel well liner removed, I can almost see all of the manifold bolts. I might be wrong, but there's a bolt behind the alternator that I believe requires unbolting the alternator to get to - I've never tried without removing the alternator.