Audible Engine Alarm

[spektrum]

It surprises me that many cars (even modern) don't alert the driver in severe event, apart from a small lamp on the dash. This could easily be missed until too late. On the weekend my engine reported low oil pressure, and I just happened to be looking at the pressure gauge as it dropped from 4kg/cm2 to almost zero. Thankfully an independent test showed the engine was actually producing the correct oil pressure.

Since this low oil pressure scare on the weekend, I started drawing up a cheap audible alarm for severe events, like low oil pressure. It could easily be expanded to include any other of the dash lamps, and eventually engine temp. I've been a bit busy lately, but I hope to post up the designs soon...

[Old Wal]

G'day spektrum. Just read this post and would be interested in what designs you come up with.I too have wondered about the lack of audible warnings in cars - when I drove trucks they all had gauges & audible warnings to draw your attention to the problem - be it low oil pressure , coolant . air pressure etc. Impossible to ignore due to the volume emitted. On some trucks if problem was engine related you apparently only had 30 sec. to shut engine down or it would do it for you.My brother's landcruiser has some kind of murphy switch that will shut engine down if oil level gets too low. Good idea.

[spektrum]

Hi Old Wal,

Unfortunately I rolled my Patrol shortly after that post. I had intentions to revisit it later after I finish rebuilding my Patrol. My thoughts were to keep it simple, just a few diodes, relay, and buzzer to trigger on critical event lamps (like the oil lamp), although it would be good to include high engine temp.

Cheers,
Luke

GQ Roll Over Thread

[threedogs]

Great idea. There's nothing to tell you whats about to happen only when its happened,

[97_gq_lwb]

you can buy them like this http://www.sig.itel.net/but it would be more fun building one i reckon i'd be interested .
working out what temps are considered safe would be interesting as even a thermal fuse could be used if operating at the right temp.
Oil pressure trigger should be a no brainer for complete loss of pressure .
But something that is adjustable to a desired level would be ideal.
My auber instruments egt has an adjustable warning circuit they do other gauges but it would get expensive.

[spektrum]

They look good. My initial designs read the information from the existing engine sensors. Would be a lot easier if these vehicles had OBD.

[Old Wal]

Auber Instruments do have a gauge that you can monitor engine temperature ( metal not coolant ) via a sensor that you attach to a bolt somewhere - maybe themostat housing. Apparently gives a more accurate reading than relying on coolant alone. Similar to Aussie made Watchdog. Beauty of it is that it will detect overheating as result of blown hose, broken belt etc. My understanding is that if you blow a radiator hose & run out of coolant your temp gauge will redline briefly ( OK if you notice ) & then begin to fall back towards cold. Anyone please correct me if I am wrong.

[spektrum]

Auber Instruments do have a gauge that you can monitor engine temperature ( metal not coolant ) via a sensor that you attach to a bolt somewhere - maybe themostat housing. Apparently gives a more accurate reading than relying on coolant alone. Similar to Aussie made Watchdog. Beauty of it is that it will detect overheating as result of blown hose, broken belt etc. My understanding is that if you blow a radiator hose & run out of coolant your temp gauge will redline briefly ( OK if you notice ) & then begin to fall back towards cold. Anyone please correct me if I am wrong.

Correct, the sensor relies on contact with the coolant. The TD42 sensor is mounted in the housing coming off the head .. It may still pickup temperature conducted along the metal, but I'm not going to test it

[ripper]

I'm planning to do this.
Our GQ has a switch in the radiator that cuts out the air con if it gets above a certain temp, I figured I can wire a buzzer into that fairly easily. For oil pressure I think I'll just tap into the warning light.

[Stropp]

I have bought a warning light and buzzer for the gu that taps into the bleed valve for the radiator, $97 cheap insurance I think. Will take some pics when it's fitted.