Average running water temp

Submitted: Wednesday, Sep 28, 2016 at 17:52
ThreadID: 133519 Views:10938 Replies:5 FollowUps:12
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Having no idea about any thing to technical i have just had fitted a "Watchdog" temp gauge to my 2000 1HZ Cruiser with after market turbo [New]
This week end towing my 2.800 T van the temp gauge was set at 90c & alarm went off, i reset to 96c & it didn't alarm. In 4th gear at 95 klmh it was showing between 86c to 91c. in overdrive it went up to 95c @ 100 klmh
Question is what is an average temperature for this model cruiser if any ?
Any advice would be handy, but bot to technical for me LOL

Dave M
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Reply By: TomH - Wednesday, Sep 28, 2016 at 19:10

Wednesday, Sep 28, 2016 at 19:10
Which goes to show that towing in 4th is better as the engine is not working so hard and runs a bit cooler. Keeping the revs in the sweet spot is always better and I found 90kph in 4th was ideal Didnt get hot didnt kick down and fuel consumption didnt suffer
90deg isnt really hot as with a 13lb radiator cap water wont boil till it gets to 135 deg approx.
I wouldnt worry about unless it gets up over 110
AnswerID: 604724

Follow Up By: pop2jocem - Wednesday, Sep 28, 2016 at 20:16

Wednesday, Sep 28, 2016 at 20:16
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.
FollowupID: 874490

Follow Up By: the redbacks - Thursday, Sep 29, 2016 at 17:47

Thursday, Sep 29, 2016 at 17:47
Thanks everyone, yep an EGR is the next thing now

Dave m
FollowupID: 874536

Follow Up By: TomH - Sunday, Oct 02, 2016 at 20:34

Sunday, Oct 02, 2016 at 20:34
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
FollowupID: 874639

Reply By: garrycol - Wednesday, Sep 28, 2016 at 20:02

Wednesday, Sep 28, 2016 at 20:02
You haven't indicated what type of sensor you are running on your Watchdog - is it one in the coolant that measures coolant temp or the one that is bolted the head or engine block that measures the temp of the metal in the engine?

If it is the latter then the temp shown may or may not have a direct correlation with coolant temp which is controlled by the thermostat and changes there may take time to show up in the metal in the block.

If it the one that is bolted to the block then there is a set procedure to set it up. The actual temp is less relevant as you are looking for changes from your normal baseline temp determined at setup.

If it is a coolant tempo sensor then ignore the above.

AnswerID: 604727

Follow Up By: CSeaJay - Wednesday, Sep 28, 2016 at 22:15

Wednesday, Sep 28, 2016 at 22:15
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
FollowupID: 874495

Follow Up By: the redbacks - Friday, Sep 30, 2016 at 18:48

Friday, Sep 30, 2016 at 18:48
Hi Garry,
It's bolted to the block,
I just set to 90c on advice from the guy that fitted it

FollowupID: 874572

Follow Up By: garrycol - Friday, Sep 30, 2016 at 19:45

Friday, Sep 30, 2016 at 19:45
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.



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.
FollowupID: 874574

Reply By: Rob K (VIC) - Thursday, Sep 29, 2016 at 09:25

Thursday, Sep 29, 2016 at 09:25
Hi Dave,

If you've just fitted an aftermarket turbo to your 1HZ motor, I highly recommend the installation of a exhaust gas temperature (EGT) gauge. The 'Watchdog' is what I would call a 'lag indicator' for engine temperatures (takes a while to reflect what the engine temperatures are doing). With the EGT you see immediately what the engine temperatures are doing, particularly under load while towing, and you can adjust the throttle position and/or gear selection accordingly. Long, sustained high engine temperatures during towing will cause issues for the 1HZ down the track (engine failure).

There's plenty of information on the EGT gauge, it's role and usefulness on this forum and many other forums. I have a turbo 1HZ fitted with the EGT gauge and use this gauge all the time while towing to keep the engine temperatures under control. I'm sure the turbo installer can discuss this gauge with you in more detail as it would be a common addition they could also supply.

Enjoy the extra responsiveness of the turboed 1HZ and keep an eye on the engine temperatures when towing. Looked after properly it will give you good service for a long time - I've done nearly 200,000kms on mine without issues.


Rob K
AnswerID: 604731

Reply By: wholehog - Friday, Sep 30, 2016 at 05:52

Friday, Sep 30, 2016 at 05:52
As advised, definately fit an EGT and drive with it, it is telling you what is happening live.

Also get educated as to pre and post turbo EGT measurement and what is safe readings for where you have the thermal sensor located.

A turboed (above atmospheric intake) 1HZ 2 valve indirect injection is not an efficient combustion chamber heat exchange into the cooling system compared to the 1HDFTE 4 valve direct injection engine.

On long runs/hills when towing on warmer days you may experience heat soak and an overwhelming of the cooling system (rising temp guage around 3/4's) and need to back off, drop even to 3rd to keep good engine airflow with a torque multiplication to help you along, but slower.

Forget 5th gear except for light flat or tailwind cruising when towing a good load. All it does is reduce the engine torque coming out of the gearbox, and a 1HZ towing needs all you've got ...often. A gearbox below 4th 1:1 is a torque multiplier, and above 4th 1:1 is a torque reducer.
AnswerID: 604759

Follow Up By: the redbacks - Friday, Sep 30, 2016 at 18:53

Friday, Sep 30, 2016 at 18:53
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

FollowupID: 874573

Reply By: Member - Phil G (SA) - Sunday, Oct 02, 2016 at 17:47

Sunday, Oct 02, 2016 at 17:47
I've had watchdogs on my daughters 1Hz 80series as well as 2 other Landcruisers including my 200series.
When we first fitted it to the 80series it went off (was set at 95) on a cool night up the Adelaide Hills which indicated the cooling system needed work. Radiator was 60% blocked so we had it rodded and fitted a new thermostat and water pump. there was also mud and grass in the condensor restricting flow through the radiator.
After that it sat between about 78 and 84 degrees, no matter how hot the weather was and would only go up slightly more with big hills. The probe was bolted to the alloy water outlet on the top of the motor.
The specs for thermostat are that it opens at 76 degrees and is fully open at 95 degrees. It tries to keep the temp around 82 degrees.
As for yours, I think it is running hotter than normal. That might just be that you have bolted on the turbo or might be something else in the cooling system.
AnswerID: 604841

Follow Up By: garrycol - Sunday, Oct 02, 2016 at 18:27

Sunday, Oct 02, 2016 at 18:27
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.
FollowupID: 874633

Follow Up By: Member - Phil G (SA) - Sunday, Oct 02, 2016 at 19:01

Sunday, Oct 02, 2016 at 19:01
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.
FollowupID: 874635

Follow Up By: Member - Phil G (SA) - Sunday, Oct 02, 2016 at 19:05

Sunday, Oct 02, 2016 at 19:05
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."
FollowupID: 874636

Follow Up By: garrycol - Monday, Oct 03, 2016 at 00:17

Monday, Oct 03, 2016 at 00:17
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".

FollowupID: 874650

Follow Up By: Member - Phil G (SA) - Monday, Oct 03, 2016 at 09:33

Monday, Oct 03, 2016 at 09:33
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.

FollowupID: 874651

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