Needle In A Hay Stack - 7.4L L29 Heater Bypass Hose

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

andy396

GMT400 Enthusiast
Joined
Jan 30, 2014
Messages
538
Reaction score
391
Location
Maryland
I'd love to find the proper hose that connects the heater bypass valve to the intake manifold. I know I could just run a generic piece of hose, but for those of you that frequent pick and pulls that are full of GMT400s nearby maybe you could keep your eyes out for one of these:

I could use the fitting also.

It's most likely going to be found on a 96+ 7.4L Suburban or Crew Cab with A/C.

You must be registered for see images attach
 

JSlezak83

I'm Awesome
Joined
Jan 13, 2019
Messages
334
Reaction score
325
Location
RI
My 7.4L crew cab doesn’t have the bypass. I wonder if it was removed at some point. Any idea what triggers the solenoid? AC pressure switch? I wouldn’t mind a little colder A/C.

I’ve seen a few Suburbans around here wit the bypass, but they were all 5.7Ls.
 

andy396

GMT400 Enthusiast
Joined
Jan 30, 2014
Messages
538
Reaction score
391
Location
Maryland
It’s triggered by the detent on the temperature control knob.
 

andy396

GMT400 Enthusiast
Joined
Jan 30, 2014
Messages
538
Reaction score
391
Location
Maryland
My 7.4L crew cab doesn’t have the bypass. I wonder if it was removed at some point.

Look for the solenoid on the fire wall. I would think it might still be there even if someone removed the bypass valve.

In my case, my donor truck didn’t have it because it was a regular cab, so I need to run the wire all the way from inside the cab, out to the solenoid.
 

JSlezak83

I'm Awesome
Joined
Jan 13, 2019
Messages
334
Reaction score
325
Location
RI
I’ll have to look a little closer, but I don’t believe there is a solenoid there, and I’m nearly positive I don’t have that vacuum line.
 

andy396

GMT400 Enthusiast
Joined
Jan 30, 2014
Messages
538
Reaction score
391
Location
Maryland
It’s a bit hidden behind the A/C accumulator/dryer. You kind of have to be looking for it to see it.
 

b454rat

I'm Awesome
Joined
Jul 25, 2019
Messages
1,729
Reaction score
1,440
Location
Windsor NY
it's been a while since I had my 97, but don't remember seeing that line. It was a ECLB. Had to replace the intake gaskets, and don't remember disconnecting that line.
 
Top