where to add water temp sensors
 

I want to add water temp sensors to each bank.

Attached are photos of the right and left front thermostat housing areas.

On the left front, I see there is a recessed area at the rear of the housing. Would this be a good place to drill and tap to add a sensor?

On the right front, there a two circular flat spots at the top of the housing. Would either or both of those be good places?

Thanks,

John
1987 XJS V12, 62000 miles

"Looks good to me" :)

I don't have any technical reason for saying that. Jaguar used the water rails for temp sensors and I'm not aware of any other convenient possibilities, so..... ?

Others will chime in.

Cheers
DD

@John

I'll be following this post as I've been thinking about doing the same thing.

I'm curious.....on my 92 car the standard temp sensor is just behind the t stat on the left hand bank. I was thinking I just had to add one sensor to the right hand bank somewhere. Are you adding 2 so they will be "matched"?

Sarc,

Yes, I want them to match. Plus, I'm going to do my own electronics on them...they will be very simple (read: "cheap"). I'll leave the stock ones connected, but will just put a small LED display inside so I can see how the banks compare. Plus...my stock meter is so flaky that I really have no idea what the water temp is half the time. I've replaced the sensor, but the meter spends most of it's time sitting at the bottom of the scale. I suspect that an issue with the funky plastic "wiring" behind the dashboard.

Thanks,

John
1987 XJS V12, 62,000 miles

On the water rail manifolds will be fine. It would be a good idea, I think, to put them on the rear manifolds each side, as this is the hottest part of the water jacket.

Greg

You can buy the electronics on ebay for about $25 delivered. Look for a "electronic digital thermometer". Blue or orange digits, programmable and has a relay circuit for an alarm or fan control. Comes with a sender that is about 3/16" diameter and 1" long.

Programmable hysterisis so that you can have a cushion where the thing is not constantly turning on and off.

Programmable offset compensation, so you might get away with a ziptie to fasten the sender to the outside of a hose.

If you use a rotary switch and multiple sensors, you could have one dash unit serving multiple sensors. But, you would not have multiple alarms.

AutoSpeed - $25 Temperature Controller and Display!

As the article mentions, make sure you get the 12vdc version, and the correct fahrenheit versus centigrade scales as you prefer.

@John

Got it. Makes sense. I'll follow this thread to see how it turns out.

@Greg

I was thinking about putting the sensors in the 2 top radiator hoses as there are nice sensor kits you can buy where they are already mounted on a piece of metal pipe and all you do is cut the hose and stick it in, then secure with jubilee clips. But I guess I'm quite far away from the "action" in the engine and they would probably read cooler.

@Plums

Amazing deal. I work in the electronics field.... No wonder no one can make any money in it these days.... Soooooo cheap

The only reason I mentioned the rear water manifolds is because there is a theory (which I happen to believe) that the water flow in the heads 'short circuits' to some degree, giving preferential flow out of the heads into the front water manifolds, and less flow to the rear manifolds. Thus it is possible that the rear of the engine runs hotter than the front. There is the 'Lutz' mod, named after the Australian V12 expert Norman Lutz, which adjusts this 'short circuit' possibility by reducing the size of the two holes in the front water manifolds, this forcing more water to the rear of the engine.

As the standard water temp gauge (on UK spec cars anyway) is on the A bank front water manifold, putting another sender a few inches downstream in the hose might not reveal much, compared with putting them in the rear of the engine. Just a thought. Though having said all that, I did about 100.000 miles with non-Lutz'd standard water manifolds and never overheated, and the engine still pulls like a train, so maybe the car has to be raced to have a problem, still, cannot do any harm I would have thought.

I wish I had know about this great piece of kit when I had my engine out, but anything I could find was far too expensive. Pic here of a Lutz'd front water manifold:

Greg

https://www.jaguarforums.com/forum/a...ine=1365321370

greg is right; at the rear of the left cylinder head, it is the hottest place on the engine cooling system, so that is where cooling temps should be monitord. coolant flows at a slow rate there,so picks up more temps.

lutz mods is a very good at directing coolant to that area(actually both heads).

pic where i put my digital temp sensor, on mine i removed that poorly engineered AAV.
, but diggie read outs are very accurate, my temps run around 170-180F ambient 80-90-F, seems to stay below 185 in traffic.

2 elec fans, and coolin system mods are just simple logic, jeez-whiz, its only an engine.

I used the back right water rail. just took out the vacuum stiwch that was dead. and stuck in a mechanical temp gauge it works great

BTW, one of the things you can do with the electronic devices linked above, since they can be mounted temporarily is to do just that to find out if there are hot spots that are of special interest.

Just make sure to mount them the first time side by side at the same spot and calibrate the offsets. Then, move them around and you will know that they should be the same relative to each other.

One further note, the centigrade version has a higher absolute range than the fahrenheit version.

where to add water temp sensors
 

Find attached two photos of my recently completed homemade temp sensor. Comprised of an LM34 temperature sensor, copper pipe, a brass fitting, a few wires and some epoxy, it seems like it should work ok for coolant temp monitoring. The LM34's upper limit is 300 degrees F and is linear through the entire range, so it's pretty easy to work with.

After mulling over the comments in this thread, and given how cheap/easy these are to make, I plan on putting one each in the front and rear water manifolds to see how much hotter it is at the rear.

Right now the radiator is out and is going to the radiator shop this afternoon.

Thanks!

John
1987 XJS V12, 62000 miles