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Discussion Starter · #1 ·
Whats the best way to check for a lower intake gasket leak at the lifter valley side? Thanks
 

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It'll be sucking oil into the intake ports.
 

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Use a smoke tester. Block off throttle body, block off line that goes from throttle body to passenger valve cover. Block off PCV line that goes to the intake (vacuum side). Hook up the smoke tester to a vacuum line, most use brake booster line. I’d set the inlet pressure to ~5psi. If you have a leak on the intake gasket, you will see smoke coming out of the nipple on the passenger side valve cover.
 

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How many times did you torque the intake manifold down?
 

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cheapo method that works well with zero cost is to fill a water or soda bottle with water, poke a hole in the cap and spray it along the lower intake with the engine running.

Listen for the water being sucked into the leak, it should also misfire/drop rpm.
 

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Smoke test would do it. There's a few different write-ups floating around on how to build one for less than $50 with lowes parts
 

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Discussion Starter · #7 ·
I have a smoke tester, i'll try the way azmack suggested, thanks.

Would a leaking lower intake gasket on the valley side cause plugs to foul (black) as well?
 

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A vacuum leak would cause a lean condition which would cause over fuel compensation
 

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Discussion Starter · #9 ·
Went out and tested. Thankfully no leak @ the lower intake. I did find a leak at the tb to valve cover fitting (on TB side) I drilled/tapped the tb and ditched that press in 90* fitting that accufab uses. Finally got my idle to drop and idle @ the command in the Holley software (y)

I also noticed a leak at the tps sensor where the throttle shaft is, but according to accufab this is normal.
 
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I have a smoke tester, i'll try the way azmack suggested, thanks.

Would a leaking lower intake gasket on the valley side cause plugs to foul (black) as well?
Check your PCV line for oil. Lower intake leak would tend to foul the plug in the area of the leak, oil from PCV will foul all plugs with the ones closest to the PCV intake vacuum line being the worst.
 

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I'm going thru this currently as well.. fouling plugs and believe it is either a lower intake leak or pcv related
 

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Went out and tested. Thankfully no leak @ the lower intake. I did find a leak at the tb to valve cover fitting (on TB side) I drilled/tapped the tb and ditched that press in 90* fitting that accufab uses. Finally got my idle to drop and idle @ the command in the Holley software (y)

I also noticed a leak at the tps sensor where the throttle shaft is, but according to accufab this is normal.
What made you initially think that you had a vacuum leak?
 

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Discussion Starter · #13 ·
The car was always idling about 100rpm over command in the Holley ecu and I could never get it down where I wanted it. I found 2 small leaks and finally got it down. They weren’t big leaks but I guess enough to keep it 100rpm higher.
 

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You must have an older accufab throttle body.

The newer ones have sealed throttle shafts.

You can't tell me that a vacuum leak "is not an issue". On mine it was pretty sizeable, I sent it in and they put seals (o-rings) on the shaft. Cost me a little but fixed a couple drive-ability issues

on smoke testing. If you put smoke pressure in the intake and it comes out of the valve cover, that doesn't necessarily mean that the intake gasket is leaking. If intake valve(s) are open, you'll get some blowby past the rings and where's it come out? The valve cover....

Another way to do it and this works great if you have a spider style intake. Seal up the PCV hole. Plug it. Then on the fresh air hose at the valve cover filler, that's where you put the smoke in. Then look down the intake. Smoke? Leak. U can use this to identify any oil leaks sources too, and for those of you who use vacuum pumps this is (or should be) SOP.
 
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