1997 gmc truck

[winford hackworth]

was wondering about the hose that goes from the left exhaust manifold to the intake. is it just for cold start up to help the motor warm up? whats the pros and cons of it if removed? reason asking was wanting to put some headers on my truck. thanks for any info given

 

[jkeaton]

IIRC, that's a leftover from the old thermac (thermostatic air cleaner) days when the carb needed controlled air temps. Does nothing on fuel injected engines, but I guess GM had them in the parts bin so they kept installing them. There should be no cons to removing it. I removed mine a long time ago.

 

[skylark]

Your 97 is a vortec engine. That isn't a heat riser tube. That is for the egr system. You can plug it and have the EGR tuned out.

 

[jkeaton]

Oh. I guess my TBI still used it. It's a piece of flexible duct. Pics would help I guess.