Hey everyone, looking for some ideas, as to if I screwed up, or if it's normal and I'm being a vehicular hypochondriac. It's a 2005 V8.

It's always had a bit of a lumpy idle for a few years, not a huge deal. But one oil change, I discovered white foam on the filler cap. PCV was toast. No huge deal, I replaced the PCV, and all was well for a while, but it was still a little lumpy (appx 690RPM).

Recently, it has been running a little hotter than usual, especially at idle. Nothing crazy, only just at the halfway point on the gauge, but since I have a 180 t-stat, and it has always had lower temps in the past, I figured something was breaking. Last week, I heard some hissing from the engine. I discovered a bunch of gunk around the hose for the crankcase breather on the drivers side. It was nasty, and the hose had also cracked. I also looked into the breather elements.... alllll kinds of nastiness in there, and drivers side hole was practically plugged with sludge. New hoses, new breathers installed. There was some carbon chunks around the breather nipple inlets, so I blew them off before I put the new hoses on.

Test ride was a huge improvement. No more hissing, temperature stays put, engine idles smoother (710RPM), and even the brakes are smoother. Long term fuel trims were at -8%, but now are at +1.2%. So it used to be rich, and now runs a bit leaner.

... my only issue is that now, I cant feel the vacuum that's described on page 5222 of the FSM. PCV valve checks out okay, but I have no vacuum on the hose that runs to the resonator box. When I take off the breather hoses at the cylinders, same thing - no vacuum.

No more obvious leaks, no smoke or anything coming out of the exhaust pipe. I am keeping a close eye on oil level incase it indicates a change. Any other ideas? Did I screw something up, or is this normal?

 

let the engine warm up. then squirt a little seafoam through each vacuum line (both directions). i'm not talking about alot as if you were going to do the whole engine, just a squirt of 1 or 2 seconds, but if there is something gunking up the lines seafoam will help loosen it.

I would also following the directions of course, add some of the liquid seafoam to the crankcase before your next oil change. This will help clean out any sludge in the oil. if i remember correctly, you put it in and idle for 15 minutes then do your oil change. do not have it in there too long. Also, what are you using for oil? I had a badly slugged engine in my old chevy and the Castrol GTX High Mileage helped to clean it up and keep it clean.

 

I'll definitely give that a shot. Since the PCV is definitely working, it must be getting air from somewhere... gunna have to play with carb cleaner to figure out where.

I ran Marvel Mystery Oil for the last 2 oil changes. Seem to have better results than with seafoam. I'm out of town for the next 9 days, but then have 10 days off. Plenty of time to diagnose this issue and rebuild the front axle.