Heater Hose Quick Disconnect to Barbed Fitting and Hose Clamp Swap/Fix

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Jared Jackson

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The plastic wears out too, and that's why I replaced mine. It's just a bad design for the owner. They're for quick assembly on the line. The originals are pot metal (I think), the ends of the hose were aluminum, the Dorman replacements seem to be steel. They corrode... I have not had that problem with brass. On top of the fitting itself, they require the expensive heater hose with the right fitting, instead of bulk hose.

Never a thing wrong with doing some cheap factory fixes and getting some tinker time in... Engineers do things for ease of assembly, cost benefits, whatever... It's always cool when we can point out a weakness and provide a cheap fix that would be easier to repair if it ever failed in BFE.
 

Jared Jackson

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Much ado about nothing; and some very real danger. If you guys are burning through these heater fittings on a frequent basis, you've got something wrong and you're not fixing the right thing. Sure, the fitting corrodes, and you need to replace the fitting. But WHY did it corrode?

1. Coolant used beyond it's service life becomes acidic and will then cause corrosion. It can also create "radiator voltage" due to the electrical action of dis-similar metals--the iron, aluminum, brass, and copper sharing the same electrolyte (coolant) become a giant low-power battery. The stray electricity can cause corrosion. Solution is to flush and replace the coolant as needed, and use a proper concentration of anti-freeze which contains corrosion inhibitors.

2. FAILURE TO PROVIDE PROPER ELECTRICAL GROUNDS can "electrify" the coolant, causing electrolysis corrosion.

Original fitting on my K1500 went about 200,000 miles. Replacement (Dorman, I think) fitting has about 100,000 miles, 18 years, and is leak-free and corrosion-free. I pulled it out of the original TBI intake manifold, and screwed it onto the replacement (ZZ4-style) manifold using a brass elbow and close nipple about four weeks ago.

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^^^ That "crappy design" fitting is not bad looking, considering it's old enough to vote.

For the record...with outside temperature at -1F, the cab gets so friggin' hot in-town I have to turn the heater fan speed or temperature down. On the highway, I have to turn the fan speed AND the temperature down.


DANGER:

The original fitting is HEAVILY RESTRICTED INTERNALLY, which your hardware-store barbed fittings are NOT. There's a reason GM engineered a restriction into the fitting--high engine speed (fast water-pump speed) can over-pressurize the heater core, leading to leakage. This isn't new or TBI-specific. GM has been restricting the water supply to the heater core for decades, to reduce the likelyhood of popping the heater core.

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Note restriction in heater fitting, lower left corner of photo.


Well... I'll be damned. You may be onto something what the restriction! That never occurred to me.

I am not going to go back to that stupid fitting... But I may look for a 3/4 hose splice with a built in restriction...

Random google search talked about putting a socket into the heater hose with a 1/4 drive opening.
 

letitsnow

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I replaced mine with a barbed fitting too. If the heater core ends up leaking because of it, the heater core probably needed to be replaced anyways.
 

big_mike

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Yea, I have never seen a over pressured heater core that wasn't corroded to all hell. If that happens the core is probably not flowing efficiently and that's causing the pressure. Those should flow so freely if you stick a water hose on the inlet it should freely flow out. It's basically a small radiator.

Simply changing this fitting should have zero negative effect on the cooling system if it's in good operating condition to begin with.
 

Moparmat2000

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Much ado about nothing; and some very real danger. If you guys are burning through these heater fittings on a frequent basis, you've got something wrong and you're not fixing the right thing. Sure, the fitting corrodes, and you need to replace the fitting. But WHY did it corrode?

1. Coolant used beyond it's service life becomes acidic and will then cause corrosion. It can also create "radiator voltage" due to the electrical action of dis-similar metals--the iron, aluminum, brass, and copper sharing the same electrolyte (coolant) become a giant low-power battery. The stray electricity can cause corrosion. Solution is to flush and replace the coolant as needed, and use a proper concentration of anti-freeze which contains corrosion inhibitors.

2. FAILURE TO PROVIDE PROPER ELECTRICAL GROUNDS can "electrify" the coolant, causing electrolysis corrosion.

Original fitting on my K1500 went about 200,000 miles. Replacement (Dorman, I think) fitting has about 100,000 miles, 18 years, and is leak-free and corrosion-free. I pulled it out of the original TBI intake manifold, and screwed it onto the replacement (ZZ4-style) manifold using a brass elbow and close nipple about four weeks ago.

You must be registered for see images


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^^^ That "crappy design" fitting is not bad looking, considering it's old enough to vote.

For the record...with outside temperature at -1F, the cab gets so friggin' hot in-town I have to turn the heater fan speed or temperature down. On the highway, I have to turn the fan speed AND the temperature down.


DANGER:

The original fitting is HEAVILY RESTRICTED INTERNALLY, which your hardware-store barbed fittings are NOT. There's a reason GM engineered a restriction into the fitting--high engine speed (fast water-pump speed) can over-pressurize the heater core, leading to leakage. This isn't new or TBI-specific. GM has been restricting the water supply to the heater core for decades, to reduce the likelyhood of popping the heater core.

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Note restriction in heater fitting, lower left corner of photo.


I put a barbed fitting on my wifes 99 burb we used to own because it was leaking, however i tack welded a fabbed up 1/8 thick circular steel plate over the end and drilled out the center of it to the same diameter as the inside of the original fitting. It is a restricted flow fitting for a reason. Too much flow and pressure, and it will blow out your heater core.

Had a buddy with a 68 mustang that kept popping heater cores after he rebuilt a 351 for it. I looked at his oem 2bbl intake manifold and the stock fitting had a restriction sized hole in it. His aftermarket intake he had put a non restricted chrome fitting. I told him theres your problem. He machined a nice press fit plug with a restricted hole for his fancy new chrome fitting on his engine. Stopped popping heater cores.
 

98 GMC

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Any reason you used the multiple barbed fitting vs the straight barb fitting like this one:

https://www.zoro.com/zoro-select-hose-barb-34-in-barb-12-in-mnpt-brass-6afj1/i/G1413142/
Did mine in 2010, no issues. It's a male adapter. Not much can go wrong with it
Did mine in 2010, no issues. It's a male adapter. Not much can go wrong with it

Going to have to replace mine on my 98 gmc. It is really rusted at the coupler. Doesn't look like it has ever been replaced. I like the idea of doing away with the quick disconnect, and using a brass or metal connector that is barbed or straight nipple. Any suggestions? Thanks
 

aleebee156

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Going to have to replace mine on my 98 gmc. It is really rusted at the coupler. Doesn't look like it has ever been replaced. I like the idea of doing away with the quick disconnect, and using a brass or metal connector that is barbed or straight nipple. Any suggestions? Thanks

FYI I ended up replacing with the OEM quick connect part. Worked great. As you will see in other posts in this forum the OEM part is heavily restricted, flow is highly restricted compared to a brass barbed fitting. I would recommend not using the barb fitting. I know there are guys having success with them, but we don’t have any info on how many miles they have on those fittings, and I’d rather not destroy a heater core. And my original fitting lasted 200,000+ miles, so if I have to replace again in 200,000 miles I’m ok with that.

So, my recommendation is now replace with OEM part, not barbed fitting. Just my opinion.


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454cid

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200k miles would probably be unusual for the factory fitting. Mine started leaking much earlier than that. I replaced it with another OEM part because the dealer had it in stock. I don't recall the specifics of replacing the second one.
 

90halfton

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FYI I ended up replacing with the OEM quick connect part. Worked great. As you will see in other posts in this forum the OEM part is heavily restricted, flow is highly restricted compared to a brass barbed fitting. I would recommend not using the barb fitting. I know there are guys having success with them, but we don’t have any info on how many miles they have on those fittings, and I’d rather not destroy a heater core. And my original fitting lasted 200,000+ miles, so if I have to replace again in 200,000 miles I’m ok with that.

So, my recommendation is now replace with OEM part, not barbed fitting. Just my opinion.


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I went to the parts house to get a new quick disconnect fitting and hose. The old guy that worked there turned me on to the barbed fitting idea and took it into the machine shop in the back and made, and pressed in a brass reducer. To keep flow and noise to the same level the stock setup had. But with an a part that wasnt ****** as ****. Keep in mind this was a real, old school parts house, with a bunch of old school mechanics and race car guys. Dont go expecting this service from the awkward child thingy working at oreillys
 

Schurkey

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^^^ That "crappy design" fitting is not bad looking, considering it's old enough to vote.

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Note restriction in heater fitting, lower left corner of photo.

I went to the parts house to get a new quick disconnect fitting and hose. The old guy that worked there turned me on to the barbed fitting idea and took it into the machine shop in the back and made, and pressed in a brass reducer. To keep flow and noise to the same level the stock setup had. But with an a part that wasnt ****** as ****.
How ****** can an OEM-style fitting be, if it entered service 18 years ago, and still looks perfect enough to re-use on a fresh engine?

At least you had enough sense to get a restriction installed. I hope it's restricted enough--smaller than the ID of 1/4" pipe.
 
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