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Jun 14th, 2026
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Joined: Sep 2009
Posts: 7,435 Likes: 122
Talk Morgan Guru
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Talk Morgan Guru
Joined: Sep 2009
Posts: 7,435 Likes: 122 |
I'm having overheating problems. Surprise, surprise. The Roadster has a replacement aluminum radiator and nice SPAL pull fan... however, it doesn't seem to blow the gale that it should, given it's capacity to move air. So, I went under the hood and poked around, only to find a two pin, female connector at the front (top) of the engine. The two wires appear to be Brown with Red trace and Yellow with Light Green trace. Have looked at online wiring diagrams for the "Federal" Roadster (that I presume means - meets federal specifications), but cannot find anything remotely like it. Thoughts?
Is it overheating while standing with the engine running (when the fan is needed) or overheating while driving, which did not happen with the old radiator?
'14 4/4 graphite grey
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Joined: Jan 2022
Posts: 50 Likes: 2
Just Getting Started
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OP
Just Getting Started
Joined: Jan 2022
Posts: 50 Likes: 2 |
I think the overheating situation is resolved. It would overhear when stopped with the engine running, not while driving. I assumed that was because the movement was forcing air over the radiator and providing cooling. As soon as I would stop, the temperature would start to increase. That's when I would expect the fan to come on and keep the engine cool (or at least from running away hot).
Does anyone know what sort of effect the cabin heating / AC cooling system has on engine temp.?
24 Super 3
23 Super 3
21 M3W
15 M3W
05 V6 Roadster
68 MGB GT 3.9L V8
67 MM 1000 Tourer
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Joined: Jul 2007
Posts: 27,809 Likes: 749
Member of the Inner Circle
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Member of the Inner Circle
Joined: Jul 2007
Posts: 27,809 Likes: 749 |
It shouldn't overheat. Check the power connectors to the fan. They flap about in the breeze & on my S1 they shorted out.
JohnV6
2022 CX Plus Four
2025 Renault Scenic Alpine etech "Yvette"
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Joined: Nov 2015
Posts: 8,671 Likes: 489
Just barreling along Needs to Get Out More!
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Just barreling along Needs to Get Out More!
Joined: Nov 2015
Posts: 8,671 Likes: 489 |
Known corrosion point on the early Roadsters are various connections & a small white resistor box usually cable tied to the top crosshead behind the rad, mine was internally non-conductive within the 'crimp' and not easy to see visually, but enough to stop the fan cutting in
Jon M
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Joined: Feb 2016
Posts: 8,667 Likes: 408
Needs to Get Out More!
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Needs to Get Out More!
Joined: Feb 2016
Posts: 8,667 Likes: 408 |
Known corrosion point on the early Roadsters are various connections & a small white resistor box usually cable tied to the top crosshead behind the rad, mine was internally non-conductive within the 'crimp' and not easy to see visually, but enough to stop the fan cutting in Morgan cunningly pre-empted this very fault. The high speed fan relay puts full volts direct to fan when it cuts in at higher temperature, bypassing the resistor fed circuit providing low speed fan. Only difference with your fault Jon would be a higher reading on temperature gauge followed eventually by deafening roar 
Richard
2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone
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Joined: May 2009
Posts: 132
L - Learner Plates On
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L - Learner Plates On
Joined: May 2009
Posts: 132 |
Does anyone know what sort of effect the cabin heating / AC cooling system has on engine temp.?
Yes! Cabin heating will pull heat from the engine cooling system, thus making it cooler. Running the AC will place extra load on the engine, plus dump heat into the AC heat exchanger, usually placed in front of the radiator. This will decrease the engine cooling efficiency. Cheers, Alexander
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