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'80 924 Blew Out All Its Coolant

 
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Mitragorz  



Joined: 30 Jun 2014
Posts: 12
Location: Manorville, NY

PostPosted: Wed May 08, 2019 10:59 am    Post subject: '80 924 Blew Out All Its Coolant Reply with quote

I was firing up my 1980 924 non-turbo to take it up to the guy I'm going to have re-seal the rear hatch. Between yard work, real work, the wife, and two kiddos under 3, I just don't have the time to do it myself.

I was letting it warm up after having to jump it with one of my work trucks, which isn't a big deal since it was sitting under a cover in the driveway all winter. I pulled the truck into the backyard, walked back to the driveway, and saw some smoke coming out from under the hood. The car is known to leak a little oil, and since it was sitting all winter I figured it was just some dust burning off. Well I opened up the hood and this is what greeted me. A geyser:

Link to video: https://youtu.be/kgwcDQpPFDo



What's neat about the picture above is that you can se the individual coolant droplets. Awesome!

The coolant was squirting out of the nipple below. If there was ever a tube attached to that, it was blown into oblivion. I'm guessing that the pressure got too great






It was also spewing vertically up out of this dimple.That's the geysey in the video and photo above. I don't know if that's a function of the tank, as over-temp/over-press protection, or if the tank is actually cracked down there and requires replacement (I'm guessing it's the latter). Hopefully that's an answer that you guys can give. I'm thinking it's cracked, bc from what I understand (well, assume I guess) is that the buildup of pressure would compress the spring on the overflow cap, and that would cause the pressure to release through that nipple. I can't imagine that the geyser is a built-in design.





So what do we think? Stuck thermostat? The first thing that came to mind was that the thermostat is stuck closed, the coolant in the block got too hot and back-fed into the overflow, causing the eruption.
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Paul  



Joined: 02 Nov 2002
Posts: 9380
Location: Southeast Wisconsin

PostPosted: Thu May 09, 2019 6:32 am    Post subject: Reply with quote

Or your radiator fans did not activate. Tank is toast.
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Mitragorz  



Joined: 30 Jun 2014
Posts: 12
Location: Manorville, NY

PostPosted: Thu May 09, 2019 7:05 am    Post subject: Reply with quote

Paul wrote:
Or your radiator fans did not activate. Tank is toast.


Hmm... Any easy way to test the fans and/or temp switch?

I already have a used tank and new thermostat on order.

In the event that I need a new thermo switch, I see a few options on Pelican:

Aux Fan: 75C, 92C
Cooling Fan: 70C, 77C, 87C

First off, what's the aux fan vs cooling fan? Secondly, which temp switch is stock, or recommended?
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Mitragorz  



Joined: 30 Jun 2014
Posts: 12
Location: Manorville, NY

PostPosted: Fri May 10, 2019 8:15 am    Post subject: Reply with quote

Anyone?
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Paul  



Joined: 02 Nov 2002
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Location: Southeast Wisconsin

PostPosted: Sat May 11, 2019 6:24 am    Post subject: Reply with quote

All the fan switch does is to provide a ground. Grounding the leads should start the fans. If they run, also touch the leads together, if they don't run, you have a bad ground on the second wire.

Stick with the stock temps for the thermostat and switch.
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Silver 98 986 3.6l 320 HP "Frank N Stein"
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Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
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Ozzie  



Joined: 12 Mar 2005
Posts: 4436
Location: Townsville, Qld. Australia

PostPosted: Sat May 11, 2019 7:56 am    Post subject: Reply with quote

[quote="Mitragorz"]
Paul wrote:

First off, what's the aux fan vs cooling fan? Secondly, which temp switch is stock, or recommended?


Cars with a/c have 2 fans
cooling fan is single
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