Heater hose neck elbow - Restricted

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Heater hose neck elbow - Restricted

Postby Morsel » Tue May 23, 2017 11:19 am

So I wanted to bring back this discussion in this area instead of the wrong area I posted last time so maybe I would get more views.

I noticed when I was re-doing my engine details, that my heater hose neck elbow was painted blue, which it was supposed to be Gold Zinc from everything I read. Well I took it off, blasted it and notice that it was restricted and not like the normal ones you see from all the suppliers. It was beyond usable even if I re zinc plated it, really pitted and just not very clean at all.

Jim was kind enough to respond with the part number of a replacement (C6AZ-18599-B) but this was not the restricted version, it was just the standard version. So I figured well, I'll try it out since it seems everyone else is using these. I installed it and ever since then my car has been getting too close to over heating in slow traffic or when idling. So I'm really thinking I want to go back to the restricted version since that's the only change that occurred.

There's one on eBay right now that I'm thinking of getting, but the guy zinc plated it silver and not gold, but I can't seem to find these anywhere, does anyone have a source for these or a decent original laying around they'd like to sell?

http://www.ebay.com/itm/Ford-Mustang-Hi ... Ciid%253A1

Thanks,

Jason
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Re: Heater hose neck elbow - Restricted

Postby 289kford » Tue May 23, 2017 2:15 pm

Though I would not think the full flow hose would create overheating issues, I found some background info hijacked from another site. allfordmustangs from Feb 09 note PN C6AZ-18599-A

Newly discovered info from Ford Small Block V8 by Bob Mannel, page J-58

History:
Heater cores in '62 Fairlanes with 221/260 V8s were being damaged by excessive water pump pressure when operated at high RPMs before the thermostat opened. (A dumb thing to be doing, but...)

Quick Fix:
Drill a 1/4" hole in the flat end of a 5/8" copper pipe cap and tack weld it on the outlet of the water elbow (inside the attached hose).

Real Fix:
New water elbow, C3OZ-18599-A, was produced with a restriction built in the end. This eliminated the problem from the 'highly efficient water pump' of the 221/260/289 engines. Mercury, and one would presume Ford, incorporated that elbow in all engines after late 1962. Even later Ford TSBs in 1968 expanded the application of the restricted elbow to 'all 1966/68 engines prior to December 15, 1967' using a new part number of C6AZ-18599-A.

The kicker (using Ford's own words):
"The new elbow can be identified by a dichromate finish which is gold-colored versus the old silver-colored one."

So, to be truly authentic, all those 'correct gold color' elbows being sold by everybody should also have a flow restriction in them. Unless you want to race your engine before the thermostat opens it probably doesn't make any difference, but its a nit to pick for those so inclined.
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Re: Heater hose neck elbow - Restricted

Postby Morsel » Tue May 23, 2017 3:01 pm

That is some good and interesting information. All I know is my temp was absolutely fine before switching to this unrestricted type of neck, so I think I'm going to either buy that one off eBay and replace it to gold or try to find one somewhere else.

Or does anyone out there have one of these available that they'd like to sell ;)

Thanks,

Jason
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Re: Heater hose neck elbow - Restricted

Postby C6ZZKGT » Tue May 23, 2017 10:59 pm

289kford wrote:Though I would not think the full flow hose would create overheating issues, I found some background info hijacked from another site. allfordmustangs from Feb 09 note PN C6AZ-18599-A

Newly discovered info from Ford Small Block V8 by Bob Mannel, page J-58

History:
Heater cores in '62 Fairlanes with 221/260 V8s were being damaged by excessive water pump pressure when operated at high RPMs before the thermostat opened. (A dumb thing to be doing, but...)

Quick Fix:
Drill a 1/4" hole in the flat end of a 5/8" copper pipe cap and tack weld it on the outlet of the water elbow (inside the attached hose).

Real Fix:
New water elbow, C3OZ-18599-A, was produced with a restriction built in the end. This eliminated the problem from the 'highly efficient water pump' of the 221/260/289 engines. Mercury, and one would presume Ford, incorporated that elbow in all engines after late 1962. Even later Ford TSBs in 1968 expanded the application of the restricted elbow to 'all 1966/68 engines prior to December 15, 1967' using a new part number of C6AZ-18599-A.

The kicker (using Ford's own words):
"The new elbow can be identified by a dichromate finish which is gold-colored versus the old silver-colored one."

So, to be truly authentic, all those 'correct gold color' elbows being sold by everybody should also have a flow restriction in them. Unless you want to race your engine before the thermostat opens it probably doesn't make any difference, but its a nit to pick for those so inclined.


Interestingly, my early FORD MPC lists the C6AZ 18599 A for a 66/67 full size Ford with a 428 PI engine. It does not specifically mention anything about a reduced flow for the heater core. The C6AZ 18599 B is listed as used for reduced flow through the heater core although that is not how they actually are as Jason has one of these and I have several NOS ones myself. There is certainly a possibility that the Ford MPC is in error however the listing never changed all the way up to the May 1975 final issue.

Keep in mind that this restrictor is only doing its job before the thermostat opens. After that, there should be no difference in flow.

GM had a similar problem on early Chevelles where the heater core would moan until the thermostat opened. They solved it with a restrictor for their heater hose connection similar to Fords.

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Re: Heater hose neck elbow - Restricted

Postby 289kford » Wed May 24, 2017 7:07 am

My PDF copy lists the 428 PI as C9ZZ-A
C6AZ-A is not listed at all, for anything. C6AZ-B is listed as restricted flow. The C3OZ-A number is not listed either. Also May 1975 final issue.

I could see the 'A' as being a service bulletin part, which some of those TSB parts did not make it to the catalog. The 'B' description, as you indicate, appears to be in error based on the info I copied and the parts you have in hand.
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Re: Heater hose neck elbow - Restricted

Postby C6ZZKGT » Wed May 24, 2017 9:35 am

289kford wrote:My PDF copy lists the 428 PI as C9ZZ-A
C6AZ-A is not listed at all, for anything. C6AZ-B is listed as restricted flow. The C3OZ-A number is not listed either. Also May 1975 final issue.

I could see the 'A' as being a service bulletin part, which some of those TSB parts did not make it to the catalog. The 'B' description, as you indicate, appears to be in error based on the info I copied and the parts you have in hand.


You are correct as far as the May 1975 issue however I also have several earlier issues and one has purposely not been updated since 1970 which leaves a lot of part numbers in the book that disappear as updates are issued. The book is very specific on the C6AZ 18599 A being for 66/67 full size Ford with PI engine. You are correct on the C9ZZ 18599 A in the May 1975 issue as it is the replacement for the C6AZ 18599 A. However since that time the C9ZZ 18599 A has been replaced with a D0AZ 18599 A. which I have in stock, and it is way different from the C6AZ 18599 B and it too does not have the restrictor.

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Re: Heater hose neck elbow - Restricted

Postby jwc66k » Sat May 27, 2017 12:21 pm

I have a NOS elbow, C6AZ-18599-B (still with ID tag, dated 011199) that has a "restriction" of 0.297 inch (a 19/64 drill slides thru easily, a 5/16 does not) at the inside top of the vertical section. The vertical section pickup has an ID of 0.409 inch, the horizontal section output has an ID of 0.540 inch. This is approximately a 50 percent reduction in cross section area of the 0.409 inch to the 0.297 inch sections.
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Re: Heater hose neck elbow - Restricted

Postby C6ZZKGT » Sat May 27, 2017 10:26 pm

jwc66k wrote:I have a NOS elbow, C6AZ-18599-B (still with ID tag, dated 011199) that has a "restriction" of 0.297 inch (a 19/64 drill slides thru easily, a 5/16 does not) at the inside top of the vertical section. The vertical section pickup has an ID of 0.409 inch, the horizontal section output has an ID of 0.540 inch. This is approximately a 50 percent reduction in cross section area of the 0.409 inch to the 0.297 inch sections.
Jim


It is good to hear that someone has the earlier production type with an actual restrictor. Ford must have felt that the restrictor was not an issue and eliminated it on the later replacement pieces with the same part number. It is also possible that Ford just made an error on the later production pieces. It would not be the first time that I have seen this type of error from Ford. :x

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