Originally Posted by oldred95

I was going to suggest smoke testing it for a leak but someone beat me to it. Interesting place to find a vacuum leak but its sealed none the less.


Here is what I've found on the 4.8, 5.3,s and 6.0s as far as oil leaks go. The most common leak is the rear of the oil pan gasket. This seems to happen on 05+ engines the most although a handful of early 6 liters have a tendency to leak there too. A rear main leak isn't really all that common unless your bearings are wasted and by that point you'll know something is up. The other leak is the rear engine cover. I've seen some that were porous and the oil just leached through the casting and on some that oil was leaking out around the bolts due to a bad gasket. I put one on a 01 6 liter and got the timing cover, gasket, bolts and rear main already installed as an assembly for 66 bucks. You can't piece it all out for that. Put it on and no more leaks. The last leak is the oil pressure sender. Just because it works doesn't mean it doesn't leak.

Originally Posted by nickleahy23

After talking with justin when he took a look at my logs, he said I have a major intake vacuum leak, since my IAC is pretty much closed the entire time the motor is warmed up..

I checked the TB gasket, both sensors on top of the intake, plug for EGR, and all seemed fine. I couldnt feel anything around the brake booster or back of the motor where the line comes in.

Im thinking my next step is to pull the intake and re seal it. Any tricks to this? basically just unhook everything, 8 bolts that hold the intake down and go from there? Can I get new seals for it, or do I reuse what is on there?

I do have an oil leak from somewhere on the back of the motor, but im guessing that couldnt cause a vacuum leak anywhere right?