Water Temp sender in water pump - 351C

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Hey guys, this seems like a dumb question, but I've wasted a bunch of time on this little thing so figured I'd try and waste your time as well.

I'm trying to add a second temp sender on my 351C. The first one in the stock location is currently being used for the electric fan. So I need a 2nd location for the actual gauge. There is an inlet is currently capped on the water pump itself just below the heater connection. Seems like a logical choice but the sender doesn't fit in that spot. Bought a bunch of adapters locally and online and they are all the wrong size. Does someone know what adapter I need to use to get the stock sender in that location? 

Sorry to waste time on such a little thing, but been screwing around with this for a couple weeks now and just want to get this done as it's holding up a bunch of other stuff for me so thought I'd ask. 

Thanks
What doesn't fit? The sender into the adapters or the adapters into the water pump?

 
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Thanks Don. I do have the bypass hose, it's just very short and mostly curved so not sure this adapter will fit in that spot very cleanly. That and it's $40+.

Tony, interesting idea, I'll think about that.

Going back to my original question, if the heater hose is OK, what about the DVCV port I looking at on the water pump? Not sure about the water flow, but if I'm not mistaken that should get engine temp water all the time regardless of the thermostat or am I mistaken? While not right at the block, it's very close and it seems like it should show pretty close to engine temp. I am hooking this to the stock engine temp gauge which doesn't actually have numbers on it. Seems like if it's close to engine temp and will let me know if I am getting a big increase that it might be fine.
You are not mistaken. Your heater core bypass hose will provide a good source of engine temperature coolant from the block at the same area as the stock sander location, as it is always flowing, unlike if it were connected to the heater core and you had the heat turned off.

 
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TheDude

Going back to my original question, if the heater hose is OK, what about the DVCV port I looking at on the water pump? Not sure about the water flow, but if I'm not mistaken that should get engine temp water all the time regardless of the thermostat or am I mistaken? While not right at the block, it's very close and it seems like it should show pretty close to engine temp. I am hooking this to the stock engine temp gauge which doesn't actually have numbers on it. Seems like if it's close to engine temp and will let me know if I am getting a big increase that it might be fine.
The hot side of the heater hose comes out of the block below the thermostat, so it is providing the same temperature as the stock temperature sender location.

The water pump pulls coolant out of the radiator and the return heater hose and pumps it through the engine, so a temperature sensor at that location will give you the cooled coolant temperature, not the engine temperature.

Our cars that don't have air conditioning don't have a valve in the hose and flow coolant through the heater all the time. A/C cars do have a valve and don't flow coolant through the hoses and heater core when the heater is turned off, so would require an "H" pipe or a bypass heater control valve.

 
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Interesting topic this as I have an issue with both my idiot light and gauge senders

Not knowing any better I put my gauge sender into the water pump and the light sender in the usual spot

Although I know for sure my engine is not getting too hot the light comes on way too early when the gauge is reading only about 140F!

I realise the gauge could be inaccurate due to where I fitted the sender but considering the light shouldn't come on at 245F something is not right with the light sender which is new

As an exercise to check the gauge I will swap the senders around and see if I get a different reading on the gauge which is currently reading about 180F when warmed up

I suspect a faulty light sender but not being able to buy another one locally will just disconnect it for now

Would be interesting to note the temp reading difference by using the water pump location which many people still use so will post results soon

 
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Interesting topic this as I have an issue with both my idiot light and gauge senders

Not knowing any better I put my gauge sender into the water pump and the light sender in the usual spot

Although I know for sure my engine is not getting too hot the light comes on way too early when the gauge is reading only about 140F!

I realise the gauge could be inaccurate due to where I fitted the sender but considering the light shouldn't come on at 245F something is not right with the light sender which is new

As an exercise to check the gauge I will swap the senders around and see if I get a different reading on the gauge which is currently reading about 180F when warmed up

I suspect a faulty light sender but not being able to buy another one locally will just disconnect it for now

Would be interesting to note the temp reading difference by using the water pump location which many people still use so will post results soon
Is your coolant flowing through your heater core? Do you have a mechanical valve stopping flow through your heater core when not in use?

 
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Interesting topic this as I have an issue with both my idiot light and gauge senders

Not knowing any better I put my gauge sender into the water pump and the light sender in the usual spot

Although I know for sure my engine is not getting too hot the light comes on way too early when the gauge is reading only about 140F!

I realise the gauge could be inaccurate due to where I fitted the sender but considering the light shouldn't come on at 245F something is not right with the light sender which is new

As an exercise to check the gauge I will swap the senders around and see if I get a different reading on the gauge which is currently reading about 180F when warmed up

I suspect a faulty light sender but not being able to buy another one locally will just disconnect it for now

Would be interesting to note the temp reading difference by using the water pump location which many people still use so will post results soon
Is your coolant flowing through your heater core? Do you have a mechanical valve stopping flow through your heater core when not in use?
Good point. I believe the valve is only used on cars with A/C. I have not seen it on 351C or 302 engines without A/C.

 
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Interesting topic this as I have an issue with both my idiot light and gauge senders

Not knowing any better I put my gauge sender into the water pump and the light sender in the usual spot

Although I know for sure my engine is not getting too hot the light comes on way too early when the gauge is reading only about 140F!

I realise the gauge could be inaccurate due to where I fitted the sender but considering the light shouldn't come on at 245F something is not right with the light sender which is new

As an exercise to check the gauge I will swap the senders around and see if I get a different reading on the gauge which is currently reading about 180F when warmed up

I suspect a faulty light sender but not being able to buy another one locally will just disconnect it for now

Would be interesting to note the temp reading difference by using the water pump location which many people still use so will post results soon
Is your coolant flowing through your heater core? Do you have a mechanical valve stopping flow through your heater core when not in use?
For those who may be interested...





 
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Interesting topic this as I have an issue with both my idiot light and gauge senders

Not knowing any better I put my gauge sender into the water pump and the light sender in the usual spot

Although I know for sure my engine is not getting too hot the light comes on way too early when the gauge is reading only about 140F!

I realise the gauge could be inaccurate due to where I fitted the sender but considering the light shouldn't come on at 245F something is not right with the light sender which is new

As an exercise to check the gauge I will swap the senders around and see if I get a different reading on the gauge which is currently reading about 180F when warmed up

I suspect a faulty light sender but not being able to buy another one locally will just disconnect it for now

Would be interesting to note the temp reading difference by using the water pump location which many people still use so will post results soon
Is your coolant flowing through your heater core? Do you have a mechanical valve stopping flow through your heater core when not in use?
Good point. I believe the valve is only used on cars with A/C. I have not seen it on 351C or 302 engines without A/C.
I threaded my heater core supply line's nipple at my block and threaded this valve into the block as a way to positively shut off the hot coolant flow to my heater core in the summer. I have aftermarket "Classic Auto Air" air conditioning system in my Mach 1, which has an electronic temperature control valve in the supply line but they can sometimes decide not to work. (Needed heat in the winter and the valve won't open or needed to use A/C in the summer and the valve wouldn't close) This valve solves that problem. 

https://www.amazon.com/gp/product/B00F34OVQ2/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1



 
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I will check the heater hose set up today and report back.

I have an Old Air a/c unit which has a cable operated heater valve so should be okay.

From memory it wasn't blowing hot air until I put the control into the warm/hot zone

Thanks EBStang for posting the diagrams it will help to understand what's going on

 
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I will check the heater hose set up today and report back.

I have an Old Air a/c unit which has a cable operated heater valve so should be okay.

From memory it wasn't blowing hot air until I put the control into the warm/hot zone

Thanks EBStang for posting the diagrams it will help to understand what's going on
No problem brother Oz...that was the intent!

 
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Thanks for the diagrams. Those are definitely worth a thousand words.

Good idea to drill it out for a 1/2" NPT tap, the walls on the fittings are thicker than the thin wall press-in tube. The inside diameter of the 1/2" fitting will not be restrictive.

 
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Well for what it was worth I swapped the temp senders around today

Virtually no difference in temperature with it running at a steady 85C/185F

The idiot light comes on later perhaps at 82C/180F but may have got previous temp wrong

Probably the only difference noted was previously with the gauge sender in the "wrong" spot at the water pump the temp went to about 92C/198F then dropped which would indicate the thermostat opening and the thermo fan coming on.

Did not get this rise/fall with the gauge sender in the block although only ran it once for this

So although there is a slight difference if anyone else was to use two senders just put the light only sender in the water pump which incidentally is also 3/8 NPT thread - my water pump is a Milodon alloy pump(actually GMB)

 
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Thanks for the diagrams. Those are definitely worth a thousand words.

Good idea to drill it out for a 1/2" NPT tap, the walls on the fittings are thicker than the thin wall press-in tube. The inside diameter of the 1/2" fitting will not be restrictive.
Just trying to help. This site is the best and it's because of contributors like you Don. I know I have personally benefited from your expertise and sometimes I get motivated enough to share some of the things I have learned. It's feels good to help others.

 
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i am also looking at using these two ports as well, so what I did was I baught two identical temp gages and hooked one to each port, there I only 3 degrees difference at all levels of temp, I now have my electric fans on one and temp gage on the other. they both work when suppost to. the fan is set to turn on at 185 and they turn on when my temp gage hits just below 190. works great.

 
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i am also looking at using these two ports as well, so what I did was I baught two identical temp gages and hooked one to each port, there I only 3 degrees difference at all levels of temp, I now have my electric fans on one and temp gage on the other. they both work when suppost to. the fan is set to turn on at 185 and they turn on when my temp gage hits just below 190. works great.
I ended up doing the same thing... sort of. I didn't have a gauge that would show the temp, so switched the sensors around and had the factory gauge in both locations and the fan in both locations. As far as I could tell it worked exactly the same in both places. The gauge showed the same cool and at temp and the fans seemed to turn on at the same time. Took the temp with an IR thermometer around the sensors in both locations and they were about the same. On different days with about the same outside temp the gauge and fans both took almost exactly the same amount of time to respond. Right now I have the fan in the factory location and the temp in the water pump. So for me this seems like it will work fine.

As usual, thanks for all the feedback in this thread. Always great info and discussion.

 
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6573stang

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so what two ports did you guys end up using? I am trying to follow along but am confused as to which two ports were used to check the temperature
 
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I put my second temp sensor/sender in place of the tps which I no long use. I use this for the mechanical temp gauge and the original location for the idiot light.
The water pump temp will be lower than engine temp due to the fact it is returning water from the rad.
 
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