If you have a s5 turbo engine with s4 upper and lower intake manifolds, would this cause you to hear a air leak?

 

No. An air leak would cause you to hear an air leak

 

So the 4 and 6 port LIM are the same?

 

No, one has 4 ports, the other 6

 

I know that. I got a 88 with supposedly a 91 motor and s4 intake manifolds on it and there sounds like there is an air leak near the lower intake manifold.

The car runs, idles and drives fine with no smoke on the start up.

When I'm driving the car the "air leak" sound seems to goes away.

 

s4 and s5 turbo manifolds swap,, both cover horizontal acv /egr passage

s4 and s5 NA dont,, s4 has acv/egr on top of centre plate ( vertical type ) ,, s5 NA has it horizontal under the primary ports,, and must have a manifold that covers this,, is is modded to cover this

 

So could this possibly be a turboed s5 N/A engine with turbo s4 intake manifolds?

 

no cause even the s4 t motor had horizontal ACV,, so its manifolds will still cover any s5 middle plate

only the s4 NA manifolds have issues with a block with horizontal ACV

 

 

So could it be a cracked intake manifold or bad gasket? I makes a loud hissing air noise.

 

Sounds like a series four NON turbo engine with series four or five turbo intake manifold.

Turbo intermediate housings have a rectangular ACV passage cut in it. The NON turbo series four has in that same area, a round passage that is blocked off with a "freeze plug" looking plug. Sooooooooooo if you put a turbo intake manifold on the series four engine the ACV air would kinda blow around the intake gasket and make noise. That would happen if you had a airpump/ACV in place.

Your images do not show up for me when I click on 'em.

 

The car is a 88 na with supposedly a 91 TII engine in it with s4 intake manifolds. It still has the s4 electronics and stuff required to make the cross series swap work (givin this is a s5 engine). Hope the pics can help a little.




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It sounds like the air is coming from this area.

 

There are vacuum hoses and nipples back there. Check them. Maybe requires a flashlight and mirror. I'd hold a 2-3' length of vacuum hose to my ear and poke around with the other end.

 

When I test for air leaks I have a little adapter I put on the front of the turbo where I can plug in a shop air hose with REGULATED pressure and check for leaks with soap and water when the motor is not running. It's amazing the leaks you can find you never knew existed.

 

could be a blown intake gasket....

 

So do what the fellow mentioned. Get a long piece of vacuum hose. One end in your ear, the other probing around where you think the sound is coming from. Easy peasy.

Not ACV or airpump related after looking at the pictures. UNKINK your brake booster hose, please.

 

+1 intake gasket...also that looks like s5 uim and lim.

 

You can also try spraying all around the intake system with brake clean and listen for a stumble

 

they are s4T
,, s5 has uneven banana bunch ( taller at rear ) and has a dimple in rotot 1 front ( secondary ) runner to clear the top mount