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

[Hoplite]

Has anyone confirmed if a 3/4 barb fits or not? I want to order a fitting tonight but don't know if it'll fit.

 

[east302]

On my 1998, it used a 1/2” NPT x 3/4” hose barb. I used this...

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...but had trouble getting the threads to seal in the intake with red Permatex. Guess I used the wrong thread sealant.






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[454cid]

Has anyone confirmed if a 3/4 barb fits or not? I want to order a fitting tonight but don't know if it'll fit.

1/2" NPT thread, 3/4" barb.

 

[454cid]

...but had trouble getting the threads to seal in the intake with red Permatex. Guess I used the wrong thread sealant.

Use pipe dope from the plumbing department.

 

[east302]

Use pipe dope from the plumbing department.

Thanks.

Any idea how far these fittings are supposed to thread into the intake? Running it about halfway in seemed pretty tight. I never could find a torque spec for the original fitting.


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[454cid]

Thanks.

Any idea how far these fittings are supposed to thread into the intake? Running it about halfway in seemed pretty tight. I never could find a torque spec for the original fitting.

Being NPT thread, I think actual depth depends on how deep the tap was run originally. I guess screw it in as tight as seems reasonable, and if it leaks screw it in a little more?

 

[bplayer405]

Just noticed my 98 5.7 is leaking at this fitting again. Time for an upgrade like this. Thanks for the write up!

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[Schurkey]

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.

 

[Jared Jackson]

Just noticed my 98 5.7 is leaking at this fitting again. Time for an upgrade like this. Thanks for the write up!

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I grabbed a brass 1/2 NPT 3/4 Barb fitting from my hardware store. Ran some teflon tape around it and put it in. My old quick connect fitting wasn't leaking, but I never liked the design of it and always read the stories about them leaking. So, I went ahead and did it. Replaced my heater hose while I was there since they were old and showing age. Also, back flushed the heater core to make sure it was flowing well. My heat is toasty this winter!

 

[454cid]

Much ado about nothing. 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 into the replacement (ZZ4-style) manifold about four weeks ago.

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.