Intake Heater hose connection?

Tiny
TBURDEN
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  • 1991 CHEVROLET 1500
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 139,000 MILES
Can I use a brass barbed 3/4 x 1/2 fitting to replace the quick connect fitting to avoid leaks. They just don't seem to last. My only worry is the pressure reducer that is in the factory fitting will not be there. Will that be a problem? I see people doing it on 95 and later models but my line goes right from the intake to the heater core. Any suggestions for some type of upgrade would be greatly appreciated.
Wednesday, August 20th, 2025 AT 6:51 AM

3 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,610 POSTS
Yep, this is a common problem and I have done many just as you have described with the brass fitting. When you try to remove the old pot metal connector it will break off leaving you will a problem, you must use a small rotary file on the end of a drill motor to slowly grind away the remaining part, only grind enough until you see the intake manifolds threads then stop and use a pick to fish the rest of the metal from the intake. This needs to be done correctly or you will ruin the intake manifold. You can install a small pipe fitting inside the heater hose to slow the coolant flow down though I have never had to do that. Please upload pictures or videos in your response of any problems so we can see what to help you with.
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Wednesday, August 20th, 2025 AT 1:16 PM
Tiny
TBURDEN
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I hear you. I have already removed the old pot metal connector and replaced it with the brass fitting in the first picture (I went with the one used in the 1Road video on YouTube). My concern is some people say if I don't use a reducer like the one in the pot metal fitting I will be putting too much flow on the cylinders and heater core and cause future problems. My question is: If I hook up just a heater hose of the same size (5/8 or 3/4) from the back of the intake to the right side of the heater core outlets (in second picture) just like it was, am I looking for problems with the cylinders or heater core from too much pressure or coolant?
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Wednesday, August 20th, 2025 AT 2:59 PM
Tiny
KEN L
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Well, they say the flow from the coolant is to fast and can make the heater core leak, so a restriction plug maybe in order.
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Wednesday, August 20th, 2025 AT 5:35 PM

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