Adding a second Water temp sensor - Physicaly

[nevtiger]

I am having a little trouble deciding where to put the extra Water Temp sensor on my engine. I have a 1972 hillman Avenger and the standard water temp sender is just under the thremostat in the head. Very similar to where the sender is mounted on a classic mini.

I need to keep this for the dash display/clocks but now have a problem of where to mount the MS sensor.

How have other people got over this?

Cheers

Nev

[nevtiger]

No one ever had this quandry before?

Surely.................

[Matt Cramer]

I'd try to put the second one also upstream of the thermostat. Maybe thread a tee into the existing hole - or you could drill and tap a second one. There's lots of ways to go about this and even some of the ones that you'd think would be less accurate (temp sensor in the radiator) can still work.

[nevtiger]

Would a T work? I supose on reflection its not much different than a capillary fed gauge. I was trying to avoid being 'beyond' the thermostat or having to take the head off!

Cheers

Nev

[nqtraderman]

There's lots of ways to go about this and even some of the ones that you'd think would be less accurate (temp sensor in the radiator) can still work.

I was thinking of putting my Coolant Temp Sensor in the bottom radiator hose - so I guess that will work too.

But being in the radiator circuit rather than behind the thermostat, would it not give a cooler reading and thus over enrichment when the engine is warm and the thermostat is not yet open - or can that be compensated for in the software ?

[66fb]

I'd think the "T" would be best. You might note how your current indicators read for reference after installing a T though.

My reasoning for the T is if the T-stat has a problem or anything happens to stop coolant flow the sensor in the radiator/hose may not report an increasing temperature (most likely decrease?).

[nevtiger]

An alternative i am thinking about now is to have the MS sensor in the normal position and then put the dash sensor into the top hose.

Then the ECU gets info in real time and the dash might lag but in normal operation it should read steady and if it changes there is a problem.

I think that will work.

Nev

[Chips60bug]

Don't change the location of your stock sensor. It doesn't really matter where you put the new sensor for the ms. It does what YOU tell it to do. What you can do is put the sensor somewhere that gets good constant flow over it, then start the car and get it warm based on what the oem temp gauge tells you, then look at megatune and record what the MS temp sensor says then set that as the "warm" temp, its not that big of a deal. Megatune doesn't need to know the Actual temp, it just needs a consistent linear reading. No matter what the actual values are. Correct me if I'm wrong.
Chip

[nevtiger]

Surely if the MS sensor is in the top hose after the thermostat the sensor will not reflec the warm up cycle of the engine and thus the MS will not be getting a linear input of the engine warming?

Nev

[Mike_Robert]

Surely if the MS sensor is in the top hose after the thermostat the sensor will not reflec the warm up cycle of the engine and thus the MS will not be getting a linear input of the engine warming?

Nev

Been there, fixed that! Drill a 0.25" hole in the thermostat plate and all is good for using the upper hose as a suitable place for coolant temp sensing. I've used this scheme for 25K+ miles. YMMV as I do not know if this would significantly increase warmup time in a cold climate. Coldest temps here are 40F or so for a week or two each year.

-Mike

[Chips60bug]

Surely if the MS sensor is in the top hose after the thermostat the sensor will not reflec the warm up cycle of the engine and thus the MS will not be getting a linear input of the engine warming?

Shoot, I have no clue where the best location for it is, I work on air cooled Just make sure it is put somewhere that gets good constant flow, if after the tstat won't work then put it before if possible, or if you don't live in a super cold place like I do, do what Mike_Robert does that sounds like it would work well.
Chip

[nqtraderman]

Been there, fixed that! Drill a 0.25" hole in the thermostat plate and all is good for using the upper hose as a suitable place for coolant temp sensing. I've used this scheme for 25K+ miles. YMMV as I do not know if this would significantly increase warmup time in a cold climate. Coldest temps here are 40F or so for a week or two each year.

-Mike

Nice job. Is that inbetween the radiator and the thermostat ? How did you make a thread for the sensor in the top tube, did you TIG weld a threaded boss to it ?

Would it be OK to put the sensor in the bottom hose instead, the space for the top hose is very limited on my car and I can't see anywhere to put a T after the thermostat all the pipes are far too small and tapping the water jacket isn't an option

[Mike_Robert]

Googling for "water temp sensor adapter" will show you the easiest way to obtain one of the temp sensor adapters. It's after the thermostat, before the radiator. The 1/4" hole drilled in the thermostat plate allows warmup to proceed correctly in my installation. I would imagine that method should work fine elsewhere. It bleeds enough engine temp coolant (with the thermostat completely closed) to give accurate warmup readings without unduly delaying warmup. I'm pretty sure a 1/4" hole at relatively low pressure can't actually move a whole lot of BTUs out of the engine. It is enough, however, to allow the sensor to read accurate temps. I've verified this by means of the stock sensor installed in the thermo housing - the numbers match at all times. As far as space is concerned, allyou have to do is remove 2" or so of the top hose and splice in the adapter. The bottom hose would be a Very Bad Idea in my opinion - that's an entirely variable temp you're reading there depending on the delta between coolant and ambient air, etc.

-Mike