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RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

After my stock coolant pipe was starting to rust out some years ago I made a single pipe reducing adapter from #316 stainless steel, which was merely supported on both ends with the rubber hose, no brackets.

Following Leadfoot and Simsports discussion on the coolant pipe I recalled that the smaller pipe was indeed blocked off and that was why I never made one and had the smaller outlet on the rear housing blocked off with a cap.

From Simsport`s experience with additional cooling it seemed beneficial to have coolant flow from the back of the head and block at all times rather than just when the heater valve was open. Realistically, on a hot day when the heater was off was the time when you needed the flow around #4, especially on a boosted engine.

Now I have modified the pipe with the addition of a 10mm ID open branch at 30 deg to the heater pipe. Essentially similar to the stock one with the hole drilled through. This branch will be connected to the rear flange like it should have been.

Does anyone have any idea if the 931s were also obstructed and why Porsche had the pipe blocked anyway? Was it to circulate more coolant through the head?

Roger

Edit to fix pic links

Oysteinrb · Joined: 21 Oct 2006 Posts: 47 Location: Norway

Scorpio · Posted: Sun Dec 20, 2009 3:43 pm Post subject:

RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

Have a vague recollection of reading in one of Ideola`s posts or compilations that his 931 tubes were also blocked.

Still don`t know why. Possibly something not performance oriented? Like more flow through the heater core so the northerner`s balls don`t fall off in winter.

Scorpio · Posted: Mon Dec 21, 2009 10:18 am Post subject:

RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

Essentially it is the stock system the way it should have been, with the smaller branch pipe open. There`s two parallel circuits. The larger 16mm pipe to the heater valve, then heater core, and to the rear flange. The smaller 12mm pipe (10 ID) is connected direct to the smaller rear flange outlet via the reinforced PVC hose.

The thinner hose always provides flow, regardless of the heater valve. With the correct OE type thermostat (additional lower valve) coolant is recirculated for fast yet even warm up. Once up to temp and thermo is open, constant flow from rear reduces local hot spot at #3 & #4.

With old and partially blocked heater core the heater output was sufficient 99% of the time. Canberra and surrounds on cold winter nights really wanted a little more, or a hotter thermo. Now that the core is a new 944 unit it provides more heat than you would ever want in Oz, even Tassie.

Scorpio · Posted: Mon Dec 21, 2009 5:52 pm Post subject:

so drilling into the coolant tube through the smaller diameter off pipe would be the equivalent...sounds too simple.

p.s my smaller pipe had a small hole in it...rust perhaps
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RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Looking at modding my coolant pipe, and had a question.

Can anyone confirm that the part of the pipe which bypasses the heater core was actually intentionally blocked off by the factory? This seems nuts to me.

TIA

rasta
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WeiBe (1987 924S 2.5t) - 931 S3

leadfoot · Posted: Mon Jun 18, 2012 6:16 pm Post subject:

think it's only on the N/A, my turbo x over wasn't blocked.
P.S you have a PM from me...
Stu
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RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

Interesting thing here is that they all appear to have the same part #. PET 79 & 85, ROW & US all list: 047 121 073 water tube.

Perhaps any holes have developed because of rust? IDK

Let`s try to get to the bottom this guys, please post your tube findings. Can you blow through it?
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Harm · Joined: 02 Apr 2009 Posts: 1376 Location: Holland

Three N/A ones that lay around:
No blockage whatsoever, sir.

…next!
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Porsche 924 NA 1982 LY7A/A3A3 _ Greater driving pleasure never harmed anyone.

RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

Doh! screwed up there.

Failed to scroll down in the PDF to the turbo engine cooling system.

Apparently there ARE 2 different part numbers. The 047 121 073 water tube is the NA unit, #8.

The pet then lists: (#10) 131 106 052 00 water tube as the turbo part.

So which, if any, are blocked or not?

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

My 931 units are not blocked either.
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