Temp alarm V low coolant alarm

Submitted: Monday, May 24, 2010 at 10:08
ThreadID: 78722 Views:11659 Replies:10 FollowUps:28
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I just fitted an engine watchdog and have noticed some discussion here about the relative values of temp v coolant alarm systems. If you can afford both and have the space for both then obviously both are a better option.

I wrote to engine watchdog and this was their reply. that I have to say I tend to agree with, does anyone have a reason why this information is incorrect or not accurate ?


=========================
Dear Doug,
I have never figured out why they feel if the engine is cold and the coolant
is absent it will guarantee the instantaneous destruction of the engine, yet
if the coolant is blocked it will just slowly overheat???
For your own peace of mind, firstly in my experience coolant tends to drip
out slowly over night and more often than not it is obvious in the morning.
When it does come out quickly and suddenly is when it is hot and under
pressure and if this happens your TM2 will alarm shortly after. Even if the
engine is dead cold and has no coolant the engines metal will rapidly
conduct the heat away from the inner core to the outside until the whole
block is too hot. The inner core of Air cooled engines do not melt down
within a few minutes of start up while the outside remains cool and neither
will your engine. Because the TM2 is so accurate and most people set the
alarm at only a few degrees above the maximum normal running temperature,
you will find you get plenty of early warning whether your coolant is
blocked or completely absent.
Hope this helps.
Regards,
Mark
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Reply By: Member - Barry (NT) - Monday, May 24, 2010 at 10:29

Monday, May 24, 2010 at 10:29
Interesting question. Having seen many engines cooked I was always careful BUT,,

I cooked my 3L pajero engine about 8 years ago (hose failure) and temp guage didn't move. I found out as I accerated away from corner, no power etc etc and when I turned down the radio I heard the bearing noise. Luckily only 2 heads required.

After this I fitted water volume sender in top radiator tank and true to form I had no other problems. But this is linked to water volume only - what if you still have the volume but cook the motor - food for thought eh.

Now have 4.2 turbo Landcruiser ute towing 3 tonne van, so along with thousands of $ worth of safety gear, diff locks, winch, bars etc, I have fitted a digital temp guage that detects the engine block temperature. It is accurate and can be "fine" tuned to the extent that you cruise all day and pull up and the increase in block temp will set it off. This is the indication that it's working.

Knowing very well how most Cruiser temp guages work (from many 1000's km in Central Aust) ie all OK with no guage movement, to very hot in the blink of an eye, I believe this guage is a good addition and from memory was about $400 fitted at Opposite Lock 3years ago.

Hope this info is helpful.
AnswerID: 417913

Follow Up By: Mike DiD - Tuesday, May 25, 2010 at 22:00

Tuesday, May 25, 2010 at 22:00
THEORY - "Because the TM2 is so accurate and most people set the
alarm at only a few degrees above the maximum normal running temperature,
you will find you get plenty of early warning whether your coolant is
blocked or completely absent. "

REALITY - "I cooked my 3L pajero engine about 8 years ago (hose failure) and temp guage didn't move. "
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Reply By: Member - Doug T (NT) - Monday, May 24, 2010 at 12:27

Monday, May 24, 2010 at 12:27
I have the Low Water alarm fitted, on 2 occasions now it has saved the engine, 1 when a hose let go, I knew straight away, 2nd and as I read your post I see about the slow overnight leak, I was camped at Balladonia for the night when escorting a load to Eucla, in the morning even before I started the engine , as soon as I turned the ignition on I knew the water level was low, an Temperature alarm would have let me start the engine, drive away from the roadhouse and the would have had to stop, the truck also would have to stop as he could not proceed without a pilot, the Low water alarm made in Ingham saved a lot of downtime and probably a high bill, being still at the roadhouse I quickly fixed the leak with Wynns heavy duty stop leak , completed the trip to Eucla, returned to Perth and had a new radiator fitted,

.
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Reply By: OzTroopy - Monday, May 24, 2010 at 12:37

Monday, May 24, 2010 at 12:37
Personally I like the in hose sensor of the "engine saver" model.

Not because Im too lazy to check my radiator in the mornings ... but because it reacts to a loss of coolant quicker than other systems ... which should provide me with a slight time advantage in dealing with the issue.

Probably a piece of mind thing more than anything else. Have yet to fit one tho ... as I bought a TM2 "engine watchdog" which also does a few other tasks for me.

Most accurate little device with an ANNOYING red display .... Temps are displayed as provided from the vehicle computer in my case .... and shows 1'c variations updated every coupla seconds. Temps are of the component it is fitted to though ... not the actual liquid temps etc. - so initial temp readings are not fully accurate IMHO ... untill everything has warmed up.

After a while one learns to ignore variations two or three degrees either side of the "normal" running temp ... same as factory dash temp gauges generally ignore fluctuations of up to 10'c either side of "normal"

I have fitted an additional sensor to the unit and regularly swap the sensor terminals to different components .... diffs, gearboxes, engine bay temps, radiator, both ends of engine for cooling system comparisons.

Later model vehicles will also accept OBD2 scanners which display digital info from the vehicle sensors via the vehicle computer.

The TM2 has been good to use to check correction operation of various factory fitted temp sensors.
AnswerID: 417926

Follow Up By: OzTroopy - Monday, May 24, 2010 at 12:45

Monday, May 24, 2010 at 12:45
Duhhhh ... temps for the TM2 are not provided from the computer ... thats the OBD2 scanner ....

.... and

Benefits of either unit will depend on expectations of the purchaser I think.


In regard to your question .... I tend to agree with the ... Wont instantly explode " line of thought .... but in fairness to the "engine saver", the escort vehicle situation posted by DougT shows "prior warning" is much better than .... finding out later.
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Follow Up By: D200Dug- Monday, May 24, 2010 at 15:16

Monday, May 24, 2010 at 15:16
I have fitted mine down near the ash tray

at least I can find where my small change is while I am driving at night now :-)

I checked the alarm this morning I seriously doubt ( even though I am pretty deaf ) I will miss hearing that go off if it ever does !
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Follow Up By: D200Dug- Monday, May 24, 2010 at 15:18

Monday, May 24, 2010 at 15:18
I agree about the escort vehicle scenario.

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Reply By: ChipPunk - Monday, May 24, 2010 at 12:47

Monday, May 24, 2010 at 12:47
I certainly disagree....


"if the engine is cold" - in reality or according to some sensor?
"and the coolant is absent" - from where - block, head, air-pockets in the head etc?
"instantaneous destruction of the engine" - yet some vehicles stress the need to "bleed" the cooling system (Why?).

"in my experience coolant tends to drip out slowly over night" - my experience is no dripping, but an air-leak so that overflow tanks are full, but radiators & heads may be empty. The number of times I hear the blown headgasket or cracked-head owner say "but I check the overflow bottle!" (...but never checked the radiator).

"The inner core of Air cooled engines do not melt down within a few minutes of start up while the outside remains cool" - what air cooled engines? Motorbikes? Even they tend to be liquid cooled. And older VWs were oil cooled. In "water" cooled car etc, oil still accounts for up to 40% of engine cooling.


I am not familiar with these particular engine alarms. I have seen an exorbitantly priced single-sensor unit on eBay (~$150).
Instead use $5 temperature sensors to trigger buzzers or lights or whatever. I have the sensors at various locations (engine head rear & front, engine block, gearbox & transfer cases, diffs, radiator upper & lower, etc.
(I also have settable voltage alarms but that is a bit more complex)

I suspect this is another product aimed at those that are no interested in DIY or those that are unable to sort the hype - like multi-electrode spark-plugs and ionising glow-plugs, charge boosting battery isolators, etc.
AnswerID: 417928

Follow Up By: Moose - Monday, May 24, 2010 at 16:50

Monday, May 24, 2010 at 16:50
G'day ChipPunk
OK once again you impress the Mooose with your knowledge of things electrical on vehicles. Mind you the Moose is easy to impress on this subject!
Would you mind providing me with a bit more information on the actual sensors you use (name, source) and how they are attached to the bit whose temp is being measured (glued?). I Googled temp sensors but confusion set in regarding contact sensors, non-contact sensors, thermocouples, RTDs, and others. Too much info for me. I need simplicity and you indicate that what you have is simple. If you prefer to do this offline please drop me an email at esantin at whba dot com dot au.
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Follow Up By: ChipPunk - Monday, May 24, 2010 at 18:04

Monday, May 24, 2010 at 18:04
Thank you Moose, though I should put you in touch with my masters...

Klixons - as from Jaycar here albeit a limited range.
Dick Smith also had them.
Oddly enough 80C is difficult to find, but that may be a bit low for typical systems anyhow (82C being a common low-temp thermostat).
90C is usually fine as a warning, but it depends where & what for.

For temps closer to coolant boiling points (eg 130C), audio suppliers may be a better source (typically 100C - 150C being used for speakers and amplifiers).


For fail-safe applications I use Normally Closed, but as extra or non-critical applications, the N.O.s are fine.

As per RACV and similar publications (Age Motoring section, old car mags etc), they are merely connected to buzzers whatever. (They are rated for 5A at 125V AC etc.) (
IE - just a normal fused +12V source like IGN etc; the switch is non-polar and isolated form chassis to switch earth or +12V to the indicator.)

Attachment is up to the individual - screw or rivet to plates, or glue.
I recently merely tied and taped to things like radiator hoses.
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Reply By: Allan B, Sunshine Coast, - Monday, May 24, 2010 at 14:00

Monday, May 24, 2010 at 14:00
Doug,

In regard to Mark's (from Engine Watchdog)response to you, I take issue with his comment re: "I have never figured out why they feel if the engine is cold and the coolant is absent it will guarantee the instantaneous destruction of the engine, yet if the coolant is blocked it will just slowly overheat???"

Firstly who is "they"? I really doubt that any sensible person would believe in "instantaneous destruction". There is probably little time difference in an engine overheating due to either absence of water or coolant blockage. The only difference is that in the latter the combustion will need to heat the water within the engine as well as the metal mass but the water will add very little extra heat-sinking to that equation. If the coolant "is blocked" the engine temperature will rise almost as rapidly as if coolant was absent.

The comparison with "Air Cooled engines" is not appropriate as they differ by having fins which dissipate heat to the surrounding air.

As for "setting the alarm at only a few degrees above the maximum normal running temperature you will find you get plenty of early warning whether your coolant is blocked or completely absent." True that you will get earlier warning but you will also get annoying alarms each time a little extra load increases the engine temperature by a few degrees. You cannot have it both ways.

It would appear that Mark is being somewhat defensive about his product when considering the relative benefits of low water level alarms. However i have no issue with the operational benefits or product quality of the Engine Saver.

The measurement of engine temperature is of prime importance in safeguarding an engine and devices such as Engine Watchdog fulfil this need better than usual OEM sensors positioned in the water stream.

I believe that early warning of potential overheating has distinct advantages. By the time that an over-temperature alarm operates you already HAVE an over-temperature and it may be inconvenient if not impossible to immediately shut-down the engine. If the water level in the radiator header tank falls by even a small amount you get an alarm notification well before you need to take urgent action. However water level alarms alone are not sufficient, there are other reasons for over temperature than water loss.

In summary, I believe that BOTH water level AND engine temperature monitors are very useful devices. It may pay to listen to those of us who experienced engine damage due to water loss rather than marketing hype.

Cheers
Allan

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Follow Up By: Member - mazcan - Monday, May 24, 2010 at 15:12

Monday, May 24, 2010 at 15:12
hi every one
when i purchased my engine watchdog i was as usuall wary of claims made by sales pitch
so after fitting it to the rear of the head i went for a drive to establish the average running temps and found 79-84 deg was the ball park so then set the alarm at 89deg chosen as what i thought would be a reasonely cautious setting after it kept going off with heat rises when pulling up suddenly and leaving it idling mode i re-adjusted it to 92deg which has proved ok for my mazda bravo diesel that done

i got to thinking out side the circle
i decided to do a trial

i drained the header tank and also removed 1.5 litres out of the top of radiator so that i had a low water situation as with loss of fluid overnight etc
this was done when the engine was cold i then started the engine and went for a short local drive within a very short time the temp went up and the engine watchdog alarm sounded
so i was happy with the trial results and am quiet confident that it will warn me in a low water situation as dicussed in this thread
hope this is of some use

ps. i am not connected with or trying to sell the product
this just my own experiences
cheers
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Reply By: Member - Phil G (SA) - Monday, May 24, 2010 at 14:46

Monday, May 24, 2010 at 14:46
I think what he says is fine.
Haven't heard of anyone cooking a motor while a TM2 reads normal temp.
AnswerID: 417940

Follow Up By: D200Dug- Monday, May 24, 2010 at 15:13

Monday, May 24, 2010 at 15:13
I understand both would be possibly better but if I can only choose and fit one ( as I can ) I am going to go for the temp gauge.

I had a look at the cheaper options on ebay and I have reservations about trusting a $10 gauge to monitor a $10,000 engine.

I really cannot see how you can cook an engine while the temp remains in the normal operating range.

Nor can I imagine driving more than a fey yards with THAT alarm blaring :-)
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Follow Up By: Member - mazcan - Monday, May 24, 2010 at 15:47

Monday, May 24, 2010 at 15:47
hi d200dug
i also went to a beach the other weekend it was a warm day
and while the going was easy on hard sand the temp remained in the normal range 79-84
but as soon as i entered a very soft section/ down a gear and up the revs the engine watchdog temp rose to 90deg and then dropped back as the beach got hard again
i have found it responded very quickly to changes in engine temp and feel confident enough to trust it
i am also wary of the cheaper options
cheers
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Follow Up By: D200Dug- Monday, May 24, 2010 at 15:56

Monday, May 24, 2010 at 15:56
Thanks ;-)
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Follow Up By: Member - Phil G (SA) - Monday, May 24, 2010 at 16:07

Monday, May 24, 2010 at 16:07
I preferred the simple option of the TM2. I didn't want to break into the cooling system to install a sensor. May daughter's 80series went over 100degrees going up a hill once and her TM2 alarmed loudly! We were watching it rise and her dash temp gauge disn't move until it got to 97 degrees. The factory temp gauge is deliberately flattened so it sits in the same spot between 50 and about 97 degrees. So all you Landcruiser owners who say your vehicle never overheats because the gauge never moves - be warned! A rising temp gauge is a late sign of overheating.
Her cooling system has since been fixed and now sits between 76 and 80 degrees.
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Follow Up By: Ozhumvee - Monday, May 24, 2010 at 21:20

Monday, May 24, 2010 at 21:20
The problem with toyota temp senders as well as being slow to rise as pointed out by Phil, is that they must have coolant actually touching them to work.
I've had two cruisers suffer total coolant loss and both times the temp gauge was slow to respond, quickly flicked up into the red and then dropped back to the cool position once the coolant had all gone despite the poor old 2H diesel nearly glowing red hot at the time.
Ever since I've had both a low water alarm and a digital temp sensor fitted to all my vehicles.
Peter
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Follow Up By: get outmore - Tuesday, May 25, 2010 at 01:53

Tuesday, May 25, 2010 at 01:53
a far more reliable way to tell if your tojo is getting warm is the aircon turning off
- thats always the first youll know of a blocked radiator with seeds etc rather than the gauge moving which comes later
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Follow Up By: Member - Graham H (QLD) - Tuesday, May 25, 2010 at 10:16

Tuesday, May 25, 2010 at 10:16
Strange that I have had the temp up to just under a 100deg and the air kept on going.

I think its only the 1HZ that does that and the 1HDFTE certainly doesnt seem to.



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Follow Up By: Member - Barry (NT) - Tuesday, May 25, 2010 at 10:30

Tuesday, May 25, 2010 at 10:30
You can't always rely on no aircon as a sign of Tojo Wagon 4.2 non turbo overheating.

We came from WA border to Alice on 42C day,,, at 120KPH temp guage went straight up to high 1/2 way through the day ,,, slowed to 110KPH guage went to normal slowly,,ALL this time aircon worked fine

this has occurred to me with different 4.2 s,,, one size doesn't fit all with Tojo guages,,,

so please don't rely on aircon to indicate a temp problem OR the Tojo guage (which can be slow to react but when it reacts it goes from normal to high very quickly),,, fit a temp sender somewhere independant of the fluid level is my preferred.
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Follow Up By: Member - Graham H (QLD) - Tuesday, May 25, 2010 at 11:24

Tuesday, May 25, 2010 at 11:24
The temp gauge only registeres whilst its immersed in water.

If the coolant drops out the gauge doesnt move at all usually

Thereby rendering it useless.


I have both a low water and a temp gauge attached to the head. (of the car)


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Reply By: Michael ( Moss Vale NSW) - Monday, May 24, 2010 at 17:29

Monday, May 24, 2010 at 17:29
HI Everyone
I pondered over this subject for some time before i went for the coolant loss setup. My thoughs were that if you split a hose, damage a radiator or and for many other reasons, lose coolant, as soon as i lose a small amount of coolant, i have an alarm. This may save me some coolant which could be helpful if it is a quick or small repair instead of the TM2 telling me that that temperature has risen and only to find , all the coolant has gone.. Coolant and temperature are really two separate issues but do overlap but the most important thing to me was if i was to only do one thing, the most inportant thing was to know the status of my coolant. What i dont know is if your coolant is fine and you vehicle is getting hot due to towing or sand driving if you can damage your engine, I wouldnt have thought so. If your engine is boiling, it normally blows the water back into the reservior, so then i have a low water alarm... My thinking is knowing the coolant is fine is most important but it is nice to know if the temp is normal also.. By the way, I made my own low coolant systen for about $60 half of that was for a Ford Falcon sensor,, works well too.. Michael
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Follow Up By: Michael ( Moss Vale NSW) - Monday, May 24, 2010 at 18:05

Monday, May 24, 2010 at 18:05
This is the Ford sensor, it is fitted to a 1/8" NPT threaded hole that normally has a vent fitting in it on the 4.2 GU TDI . It is basically a piece of stainless steel with glass filled nylon moulded around it as the body. Image Could Not Be Found Phil G mentioned about breaking into the cooling system, I think there are similar spots on some of the Toyota motors also..
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Reply By: Gazal Champion - Monday, May 24, 2010 at 17:39

Monday, May 24, 2010 at 17:39
Hi Guys,

I had fitted in the previous cruiser a low water alarm.

I did not notice any loss of coolant because I drive to work and park the vehicle and I might not see it for the rest of the day. It's summer time and a hot day and any coolant loos is evaporated before I get to the vehicle in the afternoon.

The alarm goes off after the second day, small leak in the system. Alerts me to a problem that I would not have picked up otherwise.

On another occasion...
Went out at lunch time to get some food for lunch, on returning to the vehicle I notice some small amount of water under the vehicle and put it down to airco.

Next day the alarm went off. I was sold on the alarm on both occasions.

Thank god for the low coolant alarm. Get a watchdog also and your backside is covered. Belt and braces I think they call it.

If your motor is a 1 HD FT you cant aford to take chances because they cost a fortune to rebuild.

My thoughts anyway.
Cheers Bruce.
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restless and lost on a track that I know. HL.

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Follow Up By: ChipPunk - Monday, May 24, 2010 at 18:12

Monday, May 24, 2010 at 18:12
I do like coolant (level) alarms - they should be considered standard design on modern vehicles.

Overheating with "normal" temperature indications is very dependent on the vehicle and may be less prevalent these days (they keep the temp sensor well under else above the thermostat and in places unlikely to have air (pockets)), but it is certainly not uncommon.
The problem is, if the coolant drops below the temp sender's position, the gauge etc often stays as is until the "superheated" (LOL!) steam forces past.
And way before then, it is likely to have had various hot-spots that do damage.
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Follow Up By: ChipPunk - Tuesday, May 25, 2010 at 12:24

Tuesday, May 25, 2010 at 12:24
PS - I checked out the TM2.
It's a temp sensor which feeds a digital display (with memory) and the alarm triggers on a gradient - ie, how fast the temp changes - which is settable by the user.

It should be bolted to a "solid" bit of engine - preferably the head. (Solid meaning not fins or head covers etc.)

That is a GOOD technique. As the blurb says, a sudden change in temperature can be a good indicator of coolant loss or faults. (I didn't check if it has a "max allowable temp" setting for the slow overheats.)

Not sure why they confuse the issue with air-cooled engines though.... They have solid cores - hence not the same problems with non-coolant-filled cavities around blocks & heads - that being the reason for many hot-spots and damage to typical engines.

Similar circuits can be added existing temp sensors, but if they do not register heat changes (as from low coolant) then that's pointless.
The klixons still work, but they switch when a particular temperature is reached - hence a bit delayed from the TM2 as well as being ambient relative (ie, though engines should maintain a certain temperature, some do run colder in cold ambients).

The klixon is a nice cheap & simple backup tough - especially if the TM2 does not have a "max temp" alarm point.


But IMO the TM2 is a good & reasonably price unit. Being "change" sensitive, it is not "crap" as I have seen with other (overpriced!) units.
And at the price, I doubt that any electronics hobbyist would bother building their own. (Unless they could merely add a temp sensor to their programmable onboard in-car system & display(s)....)
I hereby withdraw and apologise for my earlier comment about bullsh overpriced eBay systems in regards to the TM2! (If that isn't obvious.)


Which is better - a coolant level sensor or TM2? IMO only specific vehicle differences might decide that - they are both worthwhile.
However, the TM2 should alarm what is ultimately important - a fast temperature change. After all, a coolant level sensor will not detect a weak water pump or blockage or slipping or broke drive belt.
And I believe I have just answered my question.... The TM2 is better....
(And I like it's "bolt-on" fitting - no need to get into existing plumbing; no warranty issues; etc.)
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Follow Up By: Allan B, Sunshine Coast, - Tuesday, May 25, 2010 at 13:08

Tuesday, May 25, 2010 at 13:08
ChipPunk, How did you "checkout" the TM2 alarm?

I can find no reference on the manufacturer's websites that indicates or even suggests that the device operates with respect to "rate of change" of the engine temperature. In fact the several expressions re operation make clear reference to actual temperature setting and detection.

As for maximum range, the specifications quoted are 1 to 125C for both indication and alarm point setting in 1C increments.

A temperature alarm system incorporating a derivative function (rate of change) may have some advantage but could also introduce false alarms at times where engine load rapidly increases due to say heavy sand. The real criteria is the absolute engine temperature.

Cheers
Allan

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Follow Up By: ChipPunk - Tuesday, May 25, 2010 at 13:39

Tuesday, May 25, 2010 at 13:39
If what you say is true, then I'll stick to Klixons. $6 per measuring point, a buzzer or light etc... Why spend extra?


But from ebay-ENGINE-WATCHDOG-TM2-TEMPERATURE-SENSOR-GAUGE-ALARM-item130394207139:

To Wit:
"The sensor detects changes so quickly, drivers can see their engine temperature rise and fall degree by degree as they drive in varying traffic and road conditions.

- You can program the TM2’s alarm sensitivity to suit your engine

With a TM2 you don't even need to know your engines temperature specifications to set the overheating alarm."


But now I see the following....
"You simply note the highest temperature your engine reaches during normal driving, then set the audible alarm to go off at a few degrees higher by pressing the button on the front."

Hence I think you are correct.
Hence I argue misleading blurb where "your engines temperature specifications" means "specified" temps as opposed to "actual" temp, and references to CHANGING temperatures like "the slightest engine temperature change as it occurs" are confustigations - deliberate or otherwise.
etc
etc

If so, I withdraw my previous withdrawal and apology.
And I apologise for my overestimation of the product.
And I wish I could post-edit the above (by inserting "Ignore all that follows")

And I thank you Allan for showing that I too can get sucked in by the advertising blurb that is so effective on others. LOL!
(I'm readjusting to the new-Australia - I'm used to the more ACCC compliant days, not the current infomercial-style of cross-promotion, misinformation and garbage.)

Allan - THANKS!
Me - D'oh!! And coolant sensors and Klixons.
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Follow Up By: Allan B, Sunshine Coast, - Tuesday, May 25, 2010 at 15:29

Tuesday, May 25, 2010 at 15:29
No worries Chip (can I call you that? lol) Many marketing blurbs use rhetoric to impress but are not necessarily accurate. I thought I knew the TM2 product and decided to recheck. (Got nuthin better to do waiting for Cape York departure!)

When Engine Watchdog say "sensitivity" etc they are really referring resolution but by design the product resolution can be no better than one digit i.e. 1 degree C.
I still think it is quite a good product and easier for some to install than Clixons.

I have used a Clixon or similar thermostat on an earlier vehicle after I blew up the motor due to sudden water loss. The only concerns that I have about Clixons is that 1. They are an electromechanical device. 2. They have open-circuit contacts with the possibility of dirty contact. 3. If installed in a draft, heat cam be lost from the body and thus the sensing element is cooled and reads low. This is particularly so if clamped to a hose with inherent low thermal conductivity. It should be shielded or thermally shrouded for accurate results. But yes they are cheap.

Chip, when I display mud on my chin, please be gentle in correcting me too hey?

Cheers
Allan

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Follow Up By: ChipPunk - Tuesday, May 25, 2010 at 16:23

Tuesday, May 25, 2010 at 16:23
LOL - Chip is fine, though I'd forgotten the old adage about how well balanced we Aussies are (we have a chip on both shoulders!). Unfortunately too I had forgotten about our tall poppy syndrome - but that may simply be the new commercialism at work. (I've been away for too many years. I've been taken aback by a few responses on this site...)


And yes, the blurb is obvious. I won't bother discussing resolution versus accuracy versus repeatability, nor sensor versus detection circuitry versus display.... But damn - I thought the rate-of-change methodology was excellent. And so easy... What a pity it doesn't (yet) exist...(?)


As to Klixons, they are electro-mag devices, but probably more reliable than analog temp sensors.
But if critical, I'lll use 2, but I usually distribute a few - eg, front, centre & rear of head(s) etc.
It's similar to fitting a second single-wire earthing oil-pressure switch - I merely connect the switch outputs together - either will trigger the light or alarm. (Redundancy is almost pointless without notification, but testing & alarming is another issue.)

But as I hinted earlier - Normally Open for non-failsafe applications.
If dirty contacts are a concern or issue, I'd use Normally Closed instead, but that needs (say) a changeover relay to invert the alarm signal unless a "green is ok" display is sought.
This seems to be overkill for most. Normally Open oil-pressure switches (ie, closed with oil pressure present) only became standard with the advent of EFI. (Excluding those that used to used them for fuel pump control in carby vehicles LOL!)


As to air cooling etc - I agree, but this case was specifically for a good mounting to a solid spot. The metal-metal (or metal-glue-metal) conduction should well exceed air cooling.
But my experimentation with Klixon on rubber radiator hose proved your point - too slow & too "remote" from the heat-conducting coolant etc.


There are other temp switches too - whether small poly-fuses (or whatever they call those capacitor-like thermal fuses) or even Curie-effect switches.

But I'm happy with my existing temp sender - unlike the temp meter, it does NOT have a flat spot (now where did I read that... lol) and a voltage switch cheaper than......
And if I had EFI, I'd probably have an existing second temp sensor as a backup....


And Allan, please let me know if I am vicious - my expression can be bad.
Idiots and errors do not provoke me, only those that (should) know better that repeatedly push the same one sided accusations without answering questions or trying to express differently or seeking clarification...
But I am one of those that often has the last entry in a topic/thread - and that will usually be a question (which the alleged "more knowlegeable" never seem to answer...).
I often say "attitude is everything". However it's only in recent months I've realised that has a negative outcome as well....
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FollowupID: 688129

Reply By: Cruisin-Oz - Tuesday, May 25, 2010 at 18:19

Tuesday, May 25, 2010 at 18:19
Hi all.

I too have the TM2 in use on my 02 78 series diesel turbo. since end of 08.

I have found it difficult to use in the extreme heat conditions during build up weather in the outback. I found locating the sensor in a workable part of the engine head was based purely on making sure it would not hit the highest op. temp. (125 deg, I think...)
Finally, found a spot near the front of the engine but, it would still get up to close to max. op.TM2 temp. I would jump out of the 4wd in panic to check if there was a serious problem... fortunately it was the extreme heat conditions of the weather I believe that was the cause.

My vehicle has had no heating/engine problems and is regularly serviced.

At the moment I am down south in the cold and the vehicle is working hard towing a h/d van and the eng.temp is down and is usually around the 60-80 deg. So, my alarm setting has been set lower.

In other words extreme outside weather temps seem to play a big part in "normal" engine operating temps. and therefore the setting for when one wants the alarm to sound????and of course how hard the engine is working...

Is this a fair comment or have I not set my TM2 up properly??

Regards Reg
AnswerID: 418093

Follow Up By: D200Dug- Tuesday, May 25, 2010 at 18:55

Tuesday, May 25, 2010 at 18:55
125 degrees Celsius (255 F) is the operating range for the TM2

I have not been up in the top end for decades but I know it can get mind numbingly hot up there.

If your local mechanic thinks everything is OK then local knowledge would be the best option.

I am guessing the ambient air temperature would be around 50 to 60 oC I am not sure about the engine running at double that figure.
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FollowupID: 688154

Follow Up By: Allan B, Sunshine Coast, - Tuesday, May 25, 2010 at 22:29

Tuesday, May 25, 2010 at 22:29
Hi Reg,

I thought that the upper range of 125C was a bit low for engines operating under severe conditions in Australia and you have confirmed that.

An engine does not operate at some absolute temperature. The heat energy of a loaded engine elevates its temperature to some point above ambient so for the same load it will obviously run hotter in a high ambient than in a cold one and for higher loads it will also run hotter. Of course, in a very cold ambient the engine temperature is maintained at a suitably elevated temperature by reduced cooling air and thermostat throttling.

For this reason of differing operating temperatures, it is better to have an adjustable temperature alarm than one with a fixed setpoint such as the Clixons that ChipPunk describes although they may be satisfactory where the engine operates in a reasonably constant ambient.

I find my alarm, adjustable from the dashboard, ideal for the wide-ranging ambients and engine loads that my vehicle experiences.

Cheers
Allan

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FollowupID: 688189

Follow Up By: D200Dug- Tuesday, May 25, 2010 at 23:17

Tuesday, May 25, 2010 at 23:17
Remind me NOT to visit the top end in the build up season !


I would love to spend a wet season up there and photograph a big wet.
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FollowupID: 688196

Follow Up By: ChipPunk - Tuesday, May 25, 2010 at 23:28

Tuesday, May 25, 2010 at 23:28
Geez, if only someone could come up with a "rate of change" device....

You'd think technology would be advanced enough....

Then again, what sort of a nerd would think up a solution like that?
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FollowupID: 688199

Reply By: Flynnie - Tuesday, May 25, 2010 at 23:41

Tuesday, May 25, 2010 at 23:41
Well all this stuff has just motivated me to order a low water sensor from Engine Saver at Ingham.

I have one of those V8 cruiser traybacks where you have no direct way of inspecting the coolant level in the radiator. Took me a year to realise that (don't laugh).

My car is presently loosing coolant from some unknown spot and this has made me a bit anxious if the same was to happen to the cruiser and I did not notice.

Flynnie
AnswerID: 418165

Follow Up By: ChipPunk - Wednesday, May 26, 2010 at 12:25

Wednesday, May 26, 2010 at 12:25
Wise action.
Without an inspection method, you have little choice.

"Oh, but they are sealed!"
- Yeah, and heater and other cores never leak; clamps never loosen; hoses never craze. And of course if coolant leaks out, it will never suck air back in will it?.

I occasionally give my (cold) top hose a few quick squeezes to ensure coolant and pressure/resistance is present.
But having a regular radiator cap (with overflow bottle), it's easy enough to check. (The cap seal is bypasssing - I'm expanding out but sucking air back in.)

Just a pity I was wrong about the TM2's operation, otherwise that would have been a winner.
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FollowupID: 688247

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