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Discussion Starter · #1 ·
A couple of days ago I was checking the oil on the truck. It was fine but I noticed the coolant tank was empty. I didn’t have any pre-mix so I added water to the tank and it didn’t take much . Seemed it only needed the coolant tank filled. This still bothered me as I have had issues with head gaskets in vehicles in the past.

Didn’t use the truck until today, Tuesday, I needed to take the truck to work.
I left the house and about 15 min later I noticed the temperature gauge was still on cold.
I figured that was weird and not normal.
I got on the highway and the gauge moved up a bit but nowhere near where it should be.
Hmmmm maybe the thermostat is stuck open and that’s why it’s running so cool.

The drive to work is about 45 minutes, mostly hyway.
A few times I seen the gauge running close to normal then it would drop down again.

Just as I pulled into work the DIC showed
LOW OIL PRESSURE SHUT OFF ENGINE
What the fuk….

So most of you motor heads and back yard mechanics are thinking what?

Me
I was thinking head gasket and it’s drinking antifreeze and oil….

Any ideas yet guys ?


I went inside and figured I would check it out after I see if there is any fires to put out.
So 30 minutes later I go out and open the hood.
There is no coolant in the tank. And it smells HOT…..

I go in and get some water and start pouring it into the tank. It runs down into the engine and I hear water boiling and bubbles coming back up to the tank.
That motor was still hot enough to boil the water I was adding after 40 minutes.

Turns out it was so hot the oil got extremely thin to the point the oil pressure dropped to near zero.

How hot do you think 5-30 oil has to be to make no oil pressure???

So what happened you say..
You will never guess

The lower rad hose clamp broke in half and I drove to work with no water in the engine…….
None. 45 min with no water.

So why did the gauge say the engine was running cool ???
Because GM engineering is beyond bad.
I don’t know where the sensor is for the water temperature, but it’s not in the engine block.

So if something happens and you loose the coolant the gauge will report that the engine is running cold.
Because there is no hot coolant making it to the sensor.
Can you now say GM engineering is stupid?

You need coolant running through the system so the temp sensor can tell how hot the engine is.

Our turbos are water cooled
Our engine oil is cooled by the oil cooler that uses the engines coolant to keep the oil from getting to hot.
Our transmission needs coolant in the rad to keep the transmission temp under control.

But the way GM engineer’s designed the system if you loose coolant the gauge reads cold….
This is beyond idiotic…

I put a new hose clamp on the lower rad hose and refilled the engine with pre mix GM coolant and drive home.
So far all looks ok.
But a cast iron block with an aluminum head is not a good combination to over heat as badly as I did.

I really like this little diesel and I didn’t think it would be destroyed by no water. I figured it would be an injector…..

So now I really have to keep an eye on it as I can’t believe this didn’t crack or warp the head.
Or damage the turbo.

Hope this info keeps others from doing damage by running your truck with the coolant gauge saying the engine is cold…..

Rob

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A couple of days ago I was checking the oil on the truck. It was fine but I noticed the coolant tank was empty. I didn’t have any pre-mix so I added water to the tank and it didn’t take much . Seemed it only needed the coolant tank filled. This still bothered me as I have had issues with head gaskets in vehicles in the past.

Didn’t use the truck until today, Tuesday, I needed to take the truck to work.
I left the house and about 15 min later I noticed the temperature gauge was still on cold.
I figured that was weird and not normal.
I got on the highway and the gauge moved up a bit but nowhere near where it should be.
Hmmmm maybe the thermostat is stuck open and that’s why it’s running so cool.

The drive to work is about 45 minutes, mostly hyway.
A few times I seen the gauge running close to normal then it would drop down again.

Just as I pulled into work the DIC showed
LOW OIL PRESSURE SHUT OFF ENGINE
What the fuk….

So most of you motor heads and back yard mechanics are thinking what?

Me
I was thinking head gasket and it’s drinking antifreeze and oil….

Any ideas yet guys ?


I went inside and figured I would check it out after I see if there is any fires to put out.
So 30 minutes later I go out and open the hood.
There is no coolant in the tank. And it smells HOT…..

I go in and get some water and start pouring it into the tank. It runs down into the engine and I hear water boiling and bubbles coming back up to the tank.
That motor was still hot enough to boil the water I was adding after 40 minutes.

Turns out it was so hot the oil got extremely thin to the point the oil pressure dropped to near zero.

How hot do you think 5-30 oil has to be to make no oil pressure???

So what happened you say..
You will never guess

The lower rad hose clamp broke in half and I drove to work with no water in the engine…….
None. 45 min with no water.

So why did the gauge say the engine was running cool ???
Because GM engineering is beyond bad.
I don’t know where the sensor is for the water temperature, but it’s not in the engine block.

So if something happens and you loose the coolant the gauge will report that the engine is running cold.
Because there is no hot coolant making it to the sensor.
Can you now say GM engineering is stupid?

You need coolant running through the system so the temp sensor can tell how hot the engine is.

Our turbos are water cooled
Our engine oil is cooled by the oil cooler that uses the engines coolant to keep the oil from getting to hot.
Our transmission needs coolant in the rad to keep the transmission temp under control.

But the way GM engineer’s designed the system if you loose coolant the gauge reads cold….
This is beyond idiotic…

I put a new hose clamp on the lower rad hose and refilled the engine with pre mix GM coolant and drive home.
So far all looks ok.
But a cast iron block with an aluminum head is not a good combination to over heat as badly as I did.

I really like this little diesel and I didn’t think it would be destroyed by no water. I figured it would be an injector…..

So now I really have to keep an eye on it as I can’t believe this didn’t crack or warp the head.
Or damage the turbo.

Hope this info keeps others from doing damage by running your truck with the coolant gauge saying the engine is cold…..

Rob

View attachment 9567
View attachment 9568
Wow Rob, thanks for the heads up. I wonder if they're s a preemptive strike we could conjure up to actually show the temp someplace that would prevent this situation. Man I hope for your sake they're s no permanent engine damage.
 

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For future reference, the temp gauge on the dash is a dummy gauge and does not display anywhere near the actual coolant temp. Also, coolant temp sensors won't read correctly if they aren't submerged in coolant, an air pocket around the sensor (or no coolant at all) will result in a wrong reading. If you want to see the actual coolant temp (when the cooling system is functioning properly) you need to view the Engine Coolant Temp (ECT) PID via the OBD-II port using a scan tool or digital gauges. The dash gauge will read ~197F and not move as long as the coolant temp is between 160F and at least 220F. The normal coolant temp during operation (not towing or climbing hills) is 172-174F. I've watched the PID and compared it to the dash gauge, once the temp hits 160-165F the gauge will read a static temperature (within a couple of degrees). It will show the same temp even if the coolant gets up to 215-220F, as I also monitored it when towing a trailer up a 7% grade in Colorado during the summer. Oil temp went to 250F, trans to 220F, coolant running 212-220F. The radiator fan would roar once I let off the throttle and the trans was able to upshift but the temp gauge didn't move one bit the entire time.

Moral of the story, don't trust the temp gauge on the dash to show you anything other than "cold" or "normal," the actual numbers on the gauge are meaningless.
 

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I know the dash gauge is useless. I see it in my data logs from my i-Dash and same as you when towing. I always keep a page up on the gauge that I've set the PID's to monitor oil temp, trans temp, engine coolant temp and so on. Not that this would have had any influence in the OP problem, but It sucks that the dash gauge is not tied to the temp sensor directly so it would reflect reality and not some massaged number GM wants us to see.

I guess in my case I will set an oil temp threshold alert on my i-Dash so if I ever suffer a coolant loss I at least get warning of a high temp situation.
 
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Discussion Starter · #5 ·
So if I load the PID for the engine temp it will show the actual water temp
And if so why didn’t the idiots at GM use what ever sensor that shows the actual water temp for the gauge in the car.

I always use my phone connected to the truck and monitor turbo boost, oil temp, ect,ect,ect
So I will add the coolant temp PID.

But this is totally beyond believable that a company like GM could screw this up so badly.
Must have hired a bunch of Ford engineers…

Rob
 

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So if I load the PID for the engine temp it will show the actual water temp
And if so why didn’t the idiots at GM use what ever sensor that shows the actual water temp for the gauge in the car.

I always use my phone connected to the truck and monitor turbo boost, oil temp, ect,ect,ect
So I will add the coolant temp PID.

But this is totally beyond believable that a company like GM could screw this up so badly.
Must have hired a bunch of Ford engineers…

Rob
It's not just GM and the most likely reason is "dumb customers." Diesel engines have a much wider normal temperature range than gas engines, so imagine how much the gauge would move depending on load and then think about how many people would think something were wrong because of the large temp swings. It's the same reason why many oil pressure gauges are also dummy gauges. Take the 6.7 Cummins, it just has a pressure switch to ensure there's at least minimum oil pressure. The oil pressure gauge is actually driven 100% by a computer algorithm that estimates what the oil pressure SHOULD be when in reality it has no idea what it really is.

It's the dumbing down of society and companies designing for the lowest common denominator in order to reduce the number of warranty complaints for non issues.
 

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So if I load the PID for the engine temp it will show the actual water temp
And if so why didn’t the idiots at GM use what ever sensor that shows the actual water temp for the gauge in the car.

I always use my phone connected to the truck and monitor turbo boost, oil temp, ect,ect,ect
So I will add the coolant temp PID.

But this is totally beyond believable that a company like GM could screw this up so badly.
Must have hired a bunch of Ford engineers…

Rob
The PID I was referring to was the oil temp PID. So if the coolant crapped out via total loss at least the flowing oil would serve as a back up temp source.
 

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Discussion Starter · #8 ·
The PID I was referring to was the oil temp PID. So if the coolant crapped out via total loss at least the flowing oil would serve as a back up temp source.
I do monitor that pid.
But stupid me didn’t think the truck was over heating so I didn’t give it a second look…
 

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I do monitor that pid.
But stupid me didn’t think the truck was over heating so I didn’t give it a second look…
If your engine survived without any perceivable impact to performance or longevity and there's no obvious damage then I'd say that says something about the general durability of these engines.
 

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Discussion Starter · #10 ·
It's not just GM and the most likely reason is "dumb customers." Diesel engines have a much wider normal temperature range than gas engines, so imagine how much the gauge would move depending on load and then think about how many people would think something were wrong because of the large temp swings. It's the same reason why many oil pressure gauges are also dummy gauges. Take the 6.7 Cummins, it just has a pressure switch to ensure there's at least minimum oil pressure. The oil pressure gauge is actually driven 100% by a computer algorithm that estimates what the oil pressure SHOULD be when in reality it has no idea what it really is.

It's the dumbing down of society and companies designing for the lowest common denominator in order to reduce the number of warranty complaints for non issues.
I am 64 and I fully understand the dumbing down of society. Just talk to todays young person.
But that is no excuse for a gauge not showing an engine in the process of a melt down.

The only excuse for this temp gauge is that GMs engineering group is dumbed down.
I have seen lots of gauges with red zones at the end of the gauge and very high numbers in that red zone.
Like I been saying from the start. GM bragging about how they North American ized the 2.8 killed the reliability. If they would have left the engine alone as it is in Australia where they don’t complain about injectors blowing holes in pistons and pistons breaking at the wrist pin. We all would have a better engine.

I owned a Ford Bronco II and was blown away by this big oil pressure gauge that always read exactly the same amount weather it was cold or hot. Idling or reved up.
I just smiled, typical ford of the era…
 

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Discussion Starter · #11 ·
If your engine survived without any perceivable impact to performance or longevity and there's no obvious damage then I'd say that says something about the general durability of these engines.
I was thinking that very thing.
Time will tell. I take it to work Thursday
I hope it didn’t damage the aluminum head or the gasket.
 

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<snip>

I owned a Ford Bronco II and was blown away by this big oil pressure gauge that always read exactly the same amount weather it was cold or hot. Idling or reved up.
I just smiled, typical ford of the era…
Same as my Mustang. The "gauge" was actually driven by a normally open 6psi pressure sensing switch. Anything over 6psi energized the viscous damped "gauge" which then slowly rose to a nice comfy 60% of full scale.

I replaced the switch with a variable resistance sender but the needle still didn't move much. Full scale was capped at 60% by winding and circuit resistance.

But yes - they don't want us to know.
 

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For future reference, the temp gauge on the dash is a dummy gauge and does not display anywhere near the actual coolant temp. Also, coolant temp sensors won't read correctly if they aren't submerged in coolant, an air pocket around the sensor (or no coolant at all) will result in a wrong reading. If you want to see the actual coolant temp (when the cooling system is functioning properly) you need to view the Engine Coolant Temp (ECT) PID via the OBD-II port using a scan tool or digital gauges. The dash gauge will read ~197F and not move as long as the coolant temp is between 160F and at least 220F. The normal coolant temp during operation (not towing or climbing hills) is 172-174F. I've watched the PID and compared it to the dash gauge, once the temp hits 160-165F the gauge will read a static temperature (within a couple of degrees). It will show the same temp even if the coolant gets up to 215-220F, as I also monitored it when towing a trailer up a 7% grade in Colorado during the summer. Oil temp went to 250F, trans to 220F, coolant running 212-220F. The radiator fan would roar once I let off the throttle and the trans was able to upshift but the temp gauge didn't move one bit the entire time.

Moral of the story, don't trust the temp gauge on the dash to show you anything other than "cold" or "normal," the actual numbers on the gauge are meaningless.

Is there any DIC adder that I can call on for my 2018 Z71? I pull heavy, in 100+ heat, and feel kind of cheated by GM for this. Also silly not to have an inkling about the gauge just being a bogus hot engine check light. In my (weak) defense, for years I also pulled heavy on my '95 K2500 7500# GVWR (the "light" version), X cab, with the 350, trailer tow pack, 3.73's and 4 sp auto. On the hottest days, up hills, AC on, pulling a 5th wheel, I could hear the fan engage. But no increase in instrument engine temp. I thought it was the same here.

If no DIC adder, then would you expand on the PID you own, and how you use it?
 

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Is there any DIC adder that I can call on for my 2018 Z71? I pull heavy, in 100+ heat, and feel kind of cheated by GM for this. Also silly not to have an inkling about the gauge just being a bogus hot engine check light. In my (weak) defense, for years I also pulled heavy on my '95 K2500 7500# GVWR (the "light" version), X cab, with trailer tow pack, 3.73's and 4 sp auto. On the hottest days, up hills, AC on, pulling a 5th wheel, I could hear the fan engage. But no increase in instrument engine temp. I thought it was the same here.

If no DIC adder, then would you expand on the PID you own, and how you use it?
Any decent OBD-II digital gauges will work fine, a stand-alone unit like the ScanGauge II, an iOS or Android app with a decent OBD-II dongle, etc. There's nothing in the DIC that will display it, but it is in the OBD-II data stream.
 
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Discussion Starter · #16 ·
Rob, how's the truck?
The only thing I notice is that I can hear the turbo spooling up now. Never herd a sound from the turbo before.
Had the travel trailer out for a tow.
Filled the truck and utility trailer with fire wood.
No issues.
I have owned 4 Rangers in a row before this Colorado. The Colorado with the diesel is just amazing considering how small the diesel is …
My truck has had some really really heavy loads behind it. I am blown away by how versatile it is…
Really impressive it survived no water for that long.
So far all good. Keeping fingers crossed..
 

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@Coloradorob thank you for sharing and I am dang sure sorry that it happened to you brother.

If it were me, I would be looking to trade that truck ASAP (people can think what they will but rather CarMax eat it through an extended warranty). If you’re dead set on keeping the truck, I would be checking oil and coolant daily for a few weeks.

Having gone through a head gasket and turbo on my truck, I would offer this advice. Be sure to grab your upper radiator hose while hot, it should be firm but not so much that you can’t squeeze it. Check it again when cold or the next morning, the hose and coolant tank should have no pressure (if it does the next morning you have a problem). The usual symptoms of a bad HG were very subtle in my case. Slow unexplained coolant loss, the above over pressure in the tank, and occasional gurgling in the heater coil. It is likely a good idea to change your oil and submit a sample of your current oil to a lab for analysis.

In my case, the truck would pass the coolant exhaust gas check and it took a while before it would finally fail a compression test. In total, I spent $6,800 at a performance diesel shop (not including the thermostat and EGR cooler I threw on as a shot in the dark) to get the truck fixed right (HG, Turbo, Head resurfacing and labor). That was during COVID and prior to inflation. It took 2 months to get the parts from GM as well. Now I feel stuck with the truck because of the money invested. I surely hope your case will work out far better than mine. Please do let us know your findings or what you decide to do. Sorry to be doom and gloom, wishing you the Best of luck!
 

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Discussion Starter · #18 ·
@Coloradorob thank you for sharing and I am dang sure sorry that it happened to you brother.

If it were me, I would be looking to trade that truck ASAP (people can think what they will but rather CarMax eat it through an extended warranty). If you’re dead set on keeping the truck, I would be checking oil and coolant daily for a few weeks.

Having gone through a head gasket and turbo on my truck, I would offer this advice. Be sure to grab your upper radiator hose while hot, it should be firm but not so much that you can’t squeeze it. Check it again when cold or the next morning, the hose and coolant tank should have no pressure (if it does the next morning you have a problem). The usual symptoms of a bad HG were very subtle in my case. Slow unexplained coolant loss, the above over pressure in the tank, and occasional gurgling in the heater coil. It is likely a good idea to change your oil and submit a sample of your current oil to a lab for analysis.

In my case, the truck would pass the coolant exhaust gas check and it took a while before it would finally fail a compression test. In total, I spent $6,800 at a performance diesel shop (not including the thermostat and EGR cooler I threw on as a shot in the dark) to get the truck fixed right (HG, Turbo, Head resurfacing and labor). That was during COVID and prior to inflation. It took 2 months to get the parts from GM as well. Now I feel stuck with the truck because of the money invested. I surely hope your case will work out far better than mine. Please do let us know your findings or what you decide to do. Sorry to be doom and gloom, wishing you the Best of luck!
Thanks for the information Dan
Do you know why your HG failed ?
I have been watching the coolant level. So far so good.
I will be retiring soon and with the stock market the way it is I don’t want to spend the money on a new truck. But at the same time I would love to have a 2022 diesel with the new injectors that can stand higher pressure.
This weekend I will be hauling more firewood.
And next weekend I am pulling the travel trailer (toy hauler) with a motorcycle in the back. Around 6000 lbs
That should tell me if the head gasket is toast.
Don’t worry about the doom and gloom. I been thinking the same as you.
And I did change the oil and filter.
I will see how it goes and post an update here.

Rob
 

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I wonder if there is a place on the cylinder head or engine block to install a aftermarket sensor for a auxiliary coolant temp gauge
To what end? Are you wanting a failsafe in case you lose your coolant and don't know you're overheating like the OP experienced or are you just wanting to know the actual coolant temp? If the latter, this is available in the OBD-II data stream and any digital gauges can read it (ScanGauge II, Banks iDash, OBD-II dongle + smartphone app, etc). If the former then the easiest would be to install a surface mount temp sensor on the cylinder head and mount a digital gauge on your dash. You'd then need to get baseline cylinder head temps under load so you can set a threshold to be concerned about.
 
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