Intake leak?

Howdy all.

I just got done "rebuilding" my 02 4.0 SOHC and it ran like a ####ing mountain lion for about 100 miles (after troubleshooting a minor antifreeze leak).

Ok so I'm having a small issue now. Not quite sure what could be causing it, but here's my symptoms.

Number one first and foremost, the intake manifold sounds like it's taking a big gasp of air if I just tap the throttle quick. Sounds almost like it's coming right from the center of the intake manifold. I've checked all the vacuum lines and have found nothing. PCV valve is connected but it's not that tight. Time for a new valve cover I guess?

Second thing is it sounds like I have an exhaust leak near the engine, under heavy throttle.

Last, the brake pedal gets tougher to push after driving for a bit (obviously lack of vacuum to the booster.

Other than this, it runs great. No codes to speak of, yet.

Any guess what this could be before I go tearing into this money pit again?

You can usually find a vacuum leak around the intake seals by taking a can of Carburetor \ Throttle Body cleaner and lightly "Misting" around the joints while the engine is running at idle.

The leaking area will cause the RPM to jump up if there is indeed a leak.

If you think the brake booster isn't getting strong vacuum and you have a vacuum leak then check the hose going to the brake booster.
For the exhaust leak, check the hoses going to the DPFE. Those hoses can crack/split and it sounds like a leaky manifold. Hurts performance as well.

colintrax said:

If you think the brake booster isn't getting strong vacuum and you have a vacuum leak then check the hose going to the brake booster.
For the exhaust leak, check the hoses going to the DPFE. Those hoses can crack/split and it sounds like a leaky manifold. Hurts performance as well.

Click to expand...

Checked that already. What's the DPFE?

DeCaff2007 said:

Checked that already. What's the DPFE?

Click to expand...

Differential Pressure Sensor. EGR Tube has a fixed orifice in it. Lines to the sensor has a high and low side. Difference in pressure lets the engine computer figure out how much Exhaust Gas is getting back to the engine to control emissions.

shucker1 said:

... Difference in pressure lets the engine computer figure out how much Exhaust Gas is getting back to the engine to control emissions.

Click to expand...

Funny you should mention that. I found the problem but you were the closest.

I drove the truck to work today and by the time I got home, the symptoms were worse and I could smell exhaust fumes.

Well, look closely and you can see the problem (ignore my fuel line shield)



Yeah that whole flange fell away somehow. Here's why:

https://www.youtube.com/watch?v=XvC-OjLpNm8&feature=youtu.be

So I ended up welding that bolt into place.



I then put the whole thing back together and it runs friggin perfect! Now to do something about that fuel line shield...

Looks like the bolts just came out for the shield or did they break off?

I had actually taken them out because I had to replace that entire fuel line. What fun that was...