Dyn Blin Posted April 16, 2019 Share Posted April 16, 2019 Good evening all. I've been installing some supplemental gauges and have come to the coolant sensor. I'd like to keep the original dash gauge functional, and would prefer not to cut into one of the radiator hoses with one of those aftermarket sender mount kits. The port that houses the sensor on my 351 is conveniently accessible but I've been having trouble finding a "T" at the local ACE to install both the OE sensor and aftermarket sensors. Can anyone confirm the original sensor and port threads of 3/8 NPT? Would a modest "T" cause any issues with air bubbles seeking the high point and leaving the sensor's dry? Is there perhaps another capped port I'm not seeing I might use for the other/new sender? Thank you! Link to comment Share on other sites More sharing options...
Gary Lewis Posted April 16, 2019 Share Posted April 16, 2019 Mark - A tee doesn't work very well on coolant as there's no flow so the senders are sitting in coolant that doesn't represent what is going on in the engine. Instead I'd look for a port on the intake manifold. The passage in the front that goes from one head to the other on a Windsor is coolant and there's usually a port tapped in it with a plug run down in it. Also, there is frequently a port on the water pump with a similar plug. As for thread pitch, most stock senders are 3/8" NPT, but some aftermarket ones are 1/4" NPT. Link to comment Share on other sites More sharing options...
Steve83 Posted April 16, 2019 Share Posted April 16, 2019 I agree - you can't get anything close to an accurate temperature from a backwater. There has to be flow across the sensor/sender/switch. This is what I did: https://supermotors.net/getfile/992199/thumbnail/38hifansw.jpg Link to comment Share on other sites More sharing options...
Gary Lewis Posted April 16, 2019 Share Posted April 16, 2019 I agree - you can't get anything close to an accurate temperature from a backwater. There has to be flow across the sensor/sender/switch. This is what I did: https://supermotors.net/getfile/992199/thumbnail/38hifansw.jpg That's pretty neat, Steve. Link to comment Share on other sites More sharing options...
Dyn Blin Posted April 16, 2019 Author Share Posted April 16, 2019 I agree - you can't get anything close to an accurate temperature from a backwater. There has to be flow across the sensor/sender/switch. This is what I did: https://supermotors.net/getfile/992199/thumbnail/38hifansw.jpg Wow, Steve. That's the kind of robust and innovative solution I've learned to expect as I browse through your portfolio. My brazing technique likely isn't up to scratch for my own endeavor. Link to comment Share on other sites More sharing options...
Dyn Blin Posted April 16, 2019 Author Share Posted April 16, 2019 Mark - A tee doesn't work very well on coolant as there's no flow so the senders are sitting in coolant that doesn't represent what is going on in the engine. Instead I'd look for a port on the intake manifold. The passage in the front that goes from one head to the other on a Windsor is coolant and there's usually a port tapped in it with a plug run down in it. Also, there is frequently a port on the water pump with a similar plug. As for thread pitch, most stock senders are 3/8" NPT, but some aftermarket ones are 1/4" NPT. Gary, is this the water jacket plug on the manifold you mentioned - between the dizzy and the carb? Would it be expected to be 3/8 NPT, too? edit: Insert image Link to comment Share on other sites More sharing options...
Gary Lewis Posted April 16, 2019 Share Posted April 16, 2019 Gary, is this the water jacket plug on the manifold you mentioned - between the dizzy and the carb? Would it be expected to be 3/8 NPT, too? edit: Insert image Mark - You said is "this" but there's no pic. Did I miss something? Link to comment Share on other sites More sharing options...
Dyn Blin Posted April 16, 2019 Author Share Posted April 16, 2019 Mark - You said is "this" but there's no pic. Did I miss something? Yes, phone splices the page so I can't access the buttons. I'll edit and include the photo from my laptop shortly. (fixed) Link to comment Share on other sites More sharing options...
Gary Lewis Posted April 16, 2019 Share Posted April 16, 2019 Gary, is this the water jacket plug on the manifold you mentioned - between the dizzy and the carb? Would it be expected to be 3/8 NPT, too? edit: Insert image Mark - Probably. It looks like it is into that crossover coolant passage. And, I would expect that to be 3/8" NPT. If you break it loose you should see coolant start to seep out, and then you'll have to lower the coolant level. Link to comment Share on other sites More sharing options...
Dyn Blin Posted April 17, 2019 Author Share Posted April 17, 2019 Gary, is this the water jacket plug on the manifold you mentioned - between the dizzy and the carb? Would it be expected to be 3/8 NPT, too? edit: Insert image Thanks Gary. Indeed it is 3/8, but it appears to be something besides a coolant crossover- no coolant, and pushing a cotton bud down there found nothing when pulled back out. My guess is a vacuum port for testing? Back to drawing board- maybe I'll test my plumbing solder technique al-la-Steve83 after all. Link to comment Share on other sites More sharing options...
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