Any way to tell if intake manifold is cracked?

[todd5854]

94 240sx, rough idle, stalls sometimes, runs okay when cold, while driving or stopped and warm if you push the clutch in, the revs stay where they are, then either slowly drop to 500, or immediately drop to 500.

If you floor it (WOT), you hear a loud whining sound.. idling, it sounds cammed. Also I am hearing clicking and popping from my exhaust, so I feel this is throwing the mixture off.

Loud vacuum leak sound heard near injector number 4, but the o-ring is ok.

Sprayed starter fluid around this area and the idle goes to normal momentarily.

Any input?

[Ryanswartout]

so the home depo special $5.02 boost leak tester - SRT Forums - SRT4, SRT6, SRT8, SRT10 & Dodge Forum (http://www.srtforums.com/forums/f169/5-02-boost-leak-tester-622994/) make one of those and just get the coupler the same size as your throttle body and u can even use a bike pump to pressurise your manifold then you will be able to see what psi its at, you will leak a lil air past your valves more than likely bc its a old motor but you will build up pressure and should be able to find the leak =D

[todd5854]

that's actually a good idea! I also heard depending on the type of leak you can hold a cigar to the intake.


Problem solved though, SOMEHOW the gasket got messed up when I put it on. I have NO clue at all how that happens..

all is well now.

[Chaluska]

so the home depo special $5.02 boost leak tester - SRT Forums - SRT4, SRT6, SRT8, SRT10 & Dodge Forum (http://www.srtforums.com/forums/f169/5-02-boost-leak-tester-622994/) make one of those and just get the coupler the same size as your throttle body and u can even use a bike pump to pressurise your manifold then you will be able to see what psi its at, you will leak a lil air past your valves more than likely bc its a old motor but you will build up pressure and should be able to find the leak =D

did this with my previous KA-T setup and found several leaks.. best $6 spent ever

[todd5854]

haha, sweet. I'm gonna keep that in mind, my motor has 147k miles so it might take a few to build up pressure.. but we deleted EGR, PCV and pretty much anything else not necessary so maybe i can make it run even better

[Mikester]

Not sure how you deleted your PCV, but you need to relieve crancase pressure somehow... Hopefully you at least run a catch can to ventilate it. If everything is just plugged; this could be part of the problem.

[todd5854]

The 4 PCV valves on the bottom of the runners have been welded shut, the actual valve on the side of the engines vents to atmosphere.