Hey, I just bought this a few days ago, and I am devoid of any mechanical knowledge outside of oil changes. What is this taped up pipe that is supposed to be hooked to the exhaust manifold? What is it for, and why wouldn't it be hooked up? 89 volvo 240
I would appreciate any help.
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It is there to get warm air from the engine into the air intake instead of 100% cold outside air. It is only needed in cold climates. If you live in a warm climate with no winter than it is not really necessary.

 

if you're in California, or another place with smog inspections, it IS neccessary to be hooked up to pass.

the other end of that silver pipe is into the bottom of the airbox under the air filter, and there's a metal flap in there with a simple mechanical thermostat thats supposed to only open when its really effin cold outside. those often stick open, thus letting the car breathe overly heated air, which reduces your power, and can ruin the "MAF" Mass Air Flow meter (aka AMM, Air Mass Meter). Most folks around here wire that flap closed (smog check doesn't inspect that).

 

thanks a lot guys, you were really helpful. I live in NY, and it's not really cold anymore, so I guess I'll just leave it off.
Take care

 

I got rid of mine years ago and sprung to flap shut. I took the metal thing off the exhaust because it rattled. Cold air is good. When the engine is warm it makes no difference. I haven't noticed any adverse affects. Winter here gets pretty cold, ie negative numbers.