Making your own exhaust temp alarm

Sorry I haven't, but after a tip on a previous thread on this subject I recently purchased 3 of these:

http://www.ebay.co.uk/itm/DC-12V-LC..._Measurement_Equipment_ET&hash=item460210609d

One for the exhaust alarm on each engine, the other to measure engine bay temperature.

For just a tenner apiece, they're far more comprehensive and, well, just better than any proprietary specialised exhaust alarms out there.

I'm just in the process of fitting them at the moment.
Have had to move the instruments around on the dash to make room for them, but it'll be worth it.
Hope to post photos in due course.
 
Interesting link. Looks a bit of a bargain to me and I wonder how they manage to sell them so cheaply.

How are you planning to fit the sensor? Inside the exhaust maybe? Or tied on to the outside somehow? What is the typical temp of exhaust gases?

It will be interesting to hear how you get on.
 
bikedaft said:
does this maplin one go warm enough? (70C)

also no alarm, but if goes off range then assume too hot? £13

http://www.maplin.co.uk/3-in-1-thermometer-with-clock-34932

if your water cooled exhaust is able to be hand held reckon less than 50C working temp?
Click to expand...

Whilst you are in Maplins get yourself a laser digi thermometer. You can then measure the temps all along your exhaust or elsewhere when running normally. Mine runs at about 40-45deg C So a 70 should be fine. When I had a MOBO it had twin Exh alarms set at 75 deg C. The thinking being that if things go this hot then you should get just enough warning to stop the engine before the impeller destroys itself.
 
asteven221 said:
Interesting link. Looks a bit of a bargain to me and I wonder how they manage to sell them so cheaply.

How are you planning to fit the sensor? Inside the exhaust maybe? Or tied on to the outside somehow? What is the typical temp of exhaust gases?

It will be interesting to hear how you get on.
Click to expand...

I've taped the sensor (a shiny metal bullet shaped thing about 30mm long and 5mm diameter) to the outside of the exhaust elbow with some gaffer tape.
Although the sensor comes supplied with only 1m of wire, it's easy to lengthen by connecting more wire to it.
I measured the sensor resistance and it's several kilo-ohms, so the extra resistance of another metre or so of wire is negligible and won't affect the accuracy significantly. It's not as if I'm not after accuracy to within 0.1 of a degree anyway.

The sensor resistance drops as the temperature increases. An inverse coefficient.

There were several suppliers of the same item when I was buying mine, so although this supplier may have sold out I'm sure there will be others if you search. Don't just look for aquarium controls, I think I searched for "12v digital temperature controller".

Originally I fitted the maplin "temperature sensitive switch" kit, which appears to have been replaced by this thermostat kit http://www.maplin.co.uk/thermostat-kit-31698 and now only seems to be able to work up to 30 deg C, although the kit looks identical.

My kit had a range up to boiling point, and I calibrated it in a pot of (just below) boiling water on the stove, and hooked it up to a buzzer.
However, the new digital display is far more advanced and comprehensive, for only a marginal additional cost.

I'm just hoping the 12v model is tolerant of up to 14.8v, was wondering whether to provide it with a stabilised 12v supply.
The instructions aren't clear on this, so not sure what to do.
 
Such wisdom as I have was communicated on this thread. It was easy and cheap in my hands, and it seems ot work, though I've never had a real incident, I put a heat gun on it to test from time to time. (Sorry if this text is mangled, the new site is still not handling links properly.)
 
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