Help on Coolant Sensor Sender & Port

[Dyn Blin]

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!

[Gary Lewis]

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.

[Steve83]

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:

[Gary Lewis]

That's pretty neat, Steve.  

[Dyn Blin]

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.

[Dyn Blin]

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

[Gary Lewis]

Mark - You said is "this" but there's no pic.  Did I miss something?

[Dyn Blin]

Yes, phone splices the page so I can't access the buttons. I'll edit and include the photo from my laptop shortly.

(fixed)

[Gary Lewis]

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.

[Dyn Blin]

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.

[Gary Lewis]

Yes, that's a vacuum port.  But, closer to the distributor there's a water passage that goes between the heads.  And at the very back of the intake there's another water passage.  If either of those have a plug in them pull it and see what comes out.

[Steve83]

Dyn Blin wrote

My brazing technique...

IDK how to braze - that's just plumbing solder:



But, yes: it's robust.  That pic shows the original configuration; the first one I posted shows that I added another bung for another switch.  Later, I added a hose barb.