Average running water temp

I pretty much agree with what Tom has said. The only number I would advise is, assuming you are measuring coolant temps direct, back off a bit if the gauge gets to around 105 deg. That gives you a bit of a safety margin. Once it does boil it could be all over as cylinder head damage can occur.
If you have a turbo fitted to a 1HZ I would advise you also fit an exhaust temperature gauge (pyrometer) if you haven't already,and keep a real good eye on it. You could have coolant temps that seem quite within a safe range but the exhaust gasses could be way over what is safe.
Cheers
Pop

Thanks everyone, yep an EGR is the next thing now

Regards
Dave m

I had a temp gauge with the sensor in the top radiator hose which would also send an alarm if the water dropped out. Needed as the famous Toyota temp gauges didnt move till 10secs before the motor blows up.

Also had an EGT gauge after turbo and always tried to keep it under about 520deg.

Remember that cylinder temps will be 200 above this and Nissan pistons melt at about 775. Dont know about Toyos but didnt want to find out LOL

Yes 90 in 4th is a very good idea Keeps motor in the torque band and air flowing nicely. I also removed the flexible part of the inner guards to let the hot air through a bit better

Dont know if this helps, but on my scanguage my water temp is normally around 83 C, and I have seen it as high as 92C

Hi Garry,
It's bolted to the block,
I just set to 90c on advice from the guy that fitted it

Cheers
Dave

Hi Dave - then it bears little correlation to actual water temp.

The procedure is to get you vehicle up to operating temp and note the temp on the Watchdog.

My petrol V8 is 73 degrees where to coolant temp is about 85. You then set the alarm at about 15 degrees higher - so in my case 88 degrees (close to your 90).

You then drive and note the temp that your Watch dog shows - eg in my case in normal use the range is always between 70 and 75. If I go down a big hill in winter it might get down to 68 and if I drive up a big hill in summer it might get up to 80 - the coolant temp gauge changes a lot more - cooler when the thermostat is closed and hotter up to 95 when climbing that hill. The thermostat moderates the engine temp and there is a little lag on the temp on the block as you would expect.

For me the temp on the Watchdog goes up in summer when I stop at traffic lights where the fan is not generating a lot of air over the block so heat from the block raises the sensor temp. Likewise when the engine is turned off the heat soak from the block can raise the sensor temp quite high.

If you have your Watchdog set at 90 then if the alarm goes off when you are driving the coolant temp will be up somewhere around 100 or higher.
I think it is important to understand that the block temp is different to the coolant temp is different and you need to monitor temp changes from your baseline. Eg if I have 80 on the watchdog when normal driving I have an issue.

So monitor your coolant temp gauge, monitor what your Watchdog temp is doing (they can be doing different things) and I agree with the others for an older diesel an EGT gauge is also helpful - the computer does that on my diesel and makes changes if they get too high so I don't have to worry.

Cheers

Garry

PS - once you have determined you "normal temp" and set your alarm do not change it if it goes off in abnormal use - is a bit like putting in a bigger fuse if it blows - do something to reduce the temps not change the alarm temp.

Wow Wholehog,
Now I'm totally stuffed, so seems that I should always tow in 4th, around 95 Klmh which I normally keep to anyway, will get an exhaust gauge fitted ASAP now.

Thanks for your reply anyway

Cheers
Dave

The sensor should not be bolted anywhere near the cooling system like the thermostat housing as it just reads what the coolant is doing and most cars have a reasonable coolant temp gauge for this.
The sensor should be mounted on the head or block where it will read metal temp and not be influenced by the coolant temp.

In extreme conditions I can watch the coolant temp going up and down as the thermostat opens and closes doing what it is supposed to do to keep the temp in the right range while the Watchdog temp stays relatively stable indicating the coolant is doing what it is supposed to be doing. If coolant temp rises and the Watchdog doesn't I note it but don't worry but if the watchdog starts rising I then start to get concerned. Could mean coolant has been lost with the gauge sitting on normal but the Watchdog picks this up - though I have the combo version which also alarms if coolant is lost or is low.
Garry

Hi Garry - you said it perfectly:
"It just reads what the coolant is doing" - that's what I wanted it to do.

I'm not sure how well you know the 1Hz, but it is not the thermostat housing. The stud I used attached the outlet to the head. There is no upper and lower housings like you'd have with a thermostat.
The thermostat is located inside the lower block where the bottom radiator hose enters the motor.

In any case, here is what Engine Watchdog tells you:

"The TM2 uses the advanced electronic 'EASY FIT' heat sensor. The sensor fits like a washer under any convenient bolt on the engine that is near the heat source, such as a thermostat housing bolt, tappet cover bolt or similar."

An that is fine if you want it to do but sort of defeats the point of having one if you also have a good coolant gauge. Also mounted there, the Watchdog will suffer the same issue as OEM temp gauges - they go up if there is a slow leak and the coolant gets hotter but if you have a catastrophic coolant loss like a burst lower hose the sensor with no coolant going over it (likewise the nearby metal) does not read the hot engine and just sits on "normal".

cheers

Garry,
Its an interesting thing to discuss.

The factory gauge is not a good coolant gauge. It is not linear and is severely dampened. At any temp between 60 degrees and 95 degrees, it sits at the same spot in the middle of the gauge. That is one reason why Landcruiser owners fit TM2's.

I have two temp measurements on the 200series (I have added both a TM2 and a Scangauge). The scangauge takes the factory temp measurement from the probe dipped in the coolant and I've put the TM2 probe on an alloy housing near the water pump. The difference in temps when rising and falling is within a couple of degrees. There is pretty much no lag which surprised me.

So having a TM2 tells me an accurate temperature which does rise and fall without significant lag. And it gives me the load audible alarm should a preset temp be exceeded. I set mine at 100 degrees because I've never been able to push the 200series above 94 degrees.

As far as catastrophic leak goes, then the only reliable option is to fit a coolant level monitor in the top radiator hose.

Cheers
Phil