So I paid to have my thermostat housing replaced since I didn't have time and my garage isn't usable right now. I get it back and had to take it back the next morning due it missing badly. At least it had a CEL so the mechanic tracked it down to the plug for #3 injector. I got it back and it seems to run ok but now there's a weird rattle/harmonic around 2300 RPMs when its cold and under a load. Next is now it seems to have a surging vibration when its idling which i think is a low idle speed. It was usually around 1000-1100 but now is down around 900. Not sure what would change that.

I don't want to take it back since there's nothing I can really put a finger on and I'm not paying for them poke at it anymore. I guess I'll be going over it all again anyway. I'd at least like to get rid of the rattle. Truck has run perfect up until this point. I guess I'm just bitching right now.

I might try a video to see if anyone has a suggestion on the rattle. I'll be checking heat shields first and anything on the top of the motor they may have touched. Or looked at wrong.

 

that rattle is probably just the serpentine belt tensioner pulley that is worn out

time for a replacement pulley

 

I sure freaking hope so. It randomly went away yesterday. Starting again this morning and then immediately went away. RonD suggested I pull the accessory belt. I just haven't had time. I meant to do it last weekend when I changed the oil but I simply ran out of time. Plus I can't hear it when its in park. So hopefully I'll be able to tell when spinning everything by hand.

It's been driving me mad.

Thanks for the suggestion.

 

i replace belt tensioner pulleys every time i replace serpentine belts

 

That sounds expensive but I haven't priced them.

 

Something else the poor running... maybe the wrong t-stat !
Check out any wiring in the area of the t-stat.

Just thinking out loud.

 

actually , the factory belt tensioner pulley was not that expensive

i prefer peace of mind when i replace both parts, saves me going back in sometime soon after i replace just the belt