Restricted fitting to replace heater QD. Udated Delco fitting 15-33220

[jaydee1445]

There are several threads with the pros and cons to using brass fittings to replace the problematic quick disconnect that tends to leak and break. I'm not going to beat that dead horse but share the restricted fitting i have found.

Orginally I used a NAPA fitting but it was 5/8 so I'm going to replace it withAC Delco 15-33220 GM12597484 it is 3/4 x1/2 NPT and has the same 3/8" restriction as the OE QD fitting and is steel.

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I confirmed the OE restriction with a drill index 23/64 was a slip fit.

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I knew the chance of getting the old on out was slim as it was weeping around the base so I needed an extractor. I was able to find the discontinued Lisle/Napa 3 piece set for $14 on fleabay. NAPA 77-4029 ( If you think you are going to do the fitting I would snap one up while the are still available)

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[jaydee1445]

Remove the MAP sensor and bracket and losten the harness retaining nut to get a straight shot with the drill.
Half of the broken off end of the QD was rotted away so I went straight to the step bit.

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One of the old timer ticks I was taught was coat drills and taps with wheel bearing grease to trap the chips and keep them out of the engine. The first step cut right through with drill on forward.

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I tired reversing the drill for the next step and it caught the remaining threads and twisted them out in chunks.

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[jaydee1445]

Coating the tap in grease to trap the chips I was able to clean up the remaining crud with the tap in a socket. With a bit of pipe dope the new fitting screwed right in.

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A couple feet of hose and I was done. The Napa fitting was a bit loose on the gates safety stripe hose so be sure to get quality worm gear clamps to crank down on it. (not the crap sold in blister packs at discount parts stores)

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[454cid]

A couple feet of hose and I was done. The Napa fitting was a bit loose on the gates safety stripe hose so be sure to get quality worm gear clamps to crank down on it.rts stores)

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I'm not so familiar with the small block heater hoses.... is that 5/8" hose, or 3/4"? The barb looks like a 5/8" going by the NAPA website.

https://www.napaonline.com/en/p/BK_6601700

On my truck that would need to be a 3/4" hose barb. I have 3/4" hose running to the heater core, from the intake manifold and 5/8" running from the heater core to the radiator (return line).

Great job, getting that old fitting out.

 

[Schurkey]

Generally, either the two heater hoses are the same size, or the bigger one is on the "core-to-engine (or radiator)" return side. The "engine-to-core" supply hose is the smaller one.

I'm surprised that yours is the opposite.

 

[454cid]

Generally, either the two heater hoses are the same size, or the bigger one is on the "core-to-engine (or radiator)" return side. The "engine-to-core" supply hose is the smaller one.

I'm surprised that yours is the opposite.

5/8th's on the radiator, is the typical topic for plugging that barb on the radiator, when it's unneeded... unless I've just been assuming the size on other peoples trucks. I know mine is 5/8".

I'm pretty sure I have the diameters arranged the same as factory. When I ditched the quick connect, I cut off the aluminum tubing from the original hose and connected it directly to the brass barb I installed.

Here is the Dorman part on Rockauto. It says the inner diameter is 3/4"

More Information for DORMAN 626105

 

[Donald Mitchell]

On mine the hose going to the intake is the large one.

 

[454cid]

I just looked at heater cores.... the TYC calls the 5/8", the inlet, and the 3/4" the outlet. The GM core lists them both as 5/8. The bulk hose listing calls the 5/8" "Heater To Radiator".....so they all kinda contradict.

Oh well, even if I have it installed backwards, it's the only way that doesn't require an adapter. If I replaced my 3/4" barb, with a 5/8" barb, and connected the coolant supply from the engine to the 5/8" side of the heater core, I'd then have to use the 3/4" port to the 5/8" port on the radiator... unless I ran it to the pump, with 3/4" barb, I suppose.

 

[jaydee1445]

The manifold to core is 3/4 hose is and the NAPA fitting is 5/8. That is why a good worm gear clamp is needed to take up the slack. Many times I‘ve by-passed bad heater cores in vehicles like Cherokee’s were the dash has to come out to replace the core by looping the 3/4 hose over to the 5/8 fitting. Haven’t had a failure yet. YMMV.

 

[jaydee1445]

If you are not comfortable with a 3/4” hose on a 5\8 fitting you could always use a fox body Mustang heater hose restrictor.

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The mustang guys cheap fix is to use a stainless nut in the hose. I even thought about getting a 3/4 x 3/8 nylon bushing with the 3/4 barb at Lowes.