Heater Hose on 1991 Pontiac 3.1 LE

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- Tom S
  
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posted
17 years ago

Sat, May 6, 2006 10:35 PM

The reducer - coupler - may have been the "restrictor". Anytime you reduce the diameter of a pipe, you speed up the fluid flowing through it and reduce the pressure that the fluid exerts on the wall of the pipe. Going from a 3/4" to a 5/8" hose is about a 30% reduction in cross sectional area (about 0.44sq.in to 0.31 sq.in.). That seems like a relatively significant decrease. the inside of the reducer is probably beveled to give a smoother transition.

I don't know if the reducer is standard/original, but it seems logical that it would be since the pump outlet is obviously 3/4". How did you cram a 5/8" hose onto a 3/4" nipple anyway??

Tom S.

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- John Bailo
  
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posted
17 years ago

Sun, May 7, 2006 1:54 AM

The heater hose ( water pump to heater coil ) blew on my 1991 Pontiac

3.1 LE.

The hose is a 5/8" that runs from the heater coil, and then near the pump, joins a coupler to a short 3/4" hose that connects to the pump.

The connector sheered at one of the joints. The hose difference didn't seem that great so I jammed the 5/8" hose onto the pump.

Is that connector original equipment?

Someone told me that GM puts "restrictors" in the heater hose to reduce pressure on the heater coil. There was nothing inside the coupler -- is that standard equipment or do you think mechanic added that in?

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- John Bailo
  
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posted
17 years ago

Tue, May 9, 2006 2:26 AM

LOL.

My friend brian and I took turns. We pushed it on just less than an inch and clamped the hose on it. Definitely was a work out!

I know that arrangement will not last, however, I've gone over some online manuals from the library and strangely none of them clearly identify the coupler.

The one that is supposedly the "shop manual" has a cutaway diagram, but after the hose leaves the pump, the drawing just ends.

I've also searched Shucks online and the heater hose is an unavailable part.

I've seen some heater hoses that seem to be 5/8" with a 3/4" inch lip at the end.

I found the coupler itself in an autoparts store, but I was reluctant to put it back on because it was plastic and I still can't believe that it was rated for the heat of the coolant. As it stands now, just by touch, the heater hose gets really *hot* !