2003, 3.4L and there is a supply of coolant that goes from to heater bypass into and directly out of the throttle body. It's not really even a supply of coolant but a stagnant contact of coolant.

When I took the hoses off, I could see the tubes in and out of the TB were clogged with muck. I can't see a purpose for this design.

Can someone please enlighten me?

It is the two rubber hoses at the bottom of the TB and the coolant only passes thru a block milled into the TB. No real circulation throughout the actual body.

 

IIRC, it's to prevent the throttle body from freezing up in the winter.

 

Thanks Zipper. I wanted to bypass the TB and loop a short piece of hose on the steel tube but i thought as sure as I do, it will be critical in the smooth operation of the engine. Sounds like I could have gotten by with that instead of replacing the short hoses to the TB.

 

A buddy if mine swapped a 3400 into his Malibu and he bypassed the t/b with a loop similar to what you're saying. He lives in northern Indiana and it gets cold there sometimes and he's always been fine. You shouldn't have any problems bypassing the t/b if you choose to do so.

 

I never bought that theory. I don't know if it's true or not, but I never bought into it.

The 3100 (same basic design) from '94-'95 never had that coolant passage. I believe it was introduced in '96 to the 60* v6 engines. Keep in mind, the exhaust cross over is also directly under the throttle body.
Not to mention, many people don't let the car properly warm up for it to make a difference. And if it was to keep the plate from sticking, despite the heat shield on the exhaust cross over pipe, that would radiate enough heat to stop that.
I drove a '94 Grand Am with a 3100 and no throttle body coolant passage for 9 years (sold with 215K miles) and I drove it in some crazy cold weather (below 0 temps, the regulator on my gas meter froze, but the Grand Am ran faithfully).

The theory I buy into (but still don't know if it's right) is that it has to do with improving MPG by slightly warming incoming air as it enters the throttle body.

Either way, I think bypassing it is a wise idea myself. I did it on the 3800 in my Monte and no issues.