Engine operating temperature

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

What is the engine operating temperature of the CRD R428 engine ? apparently the thermostat is 176F,
but when I got my OBD2 gadget plugged in with my phone and the torque pro app, it shows 167F.

I talked to a professional commercial diesel tuner about the CRD and he told me that you need 2600F on the top of the piston to make some good power. he said the thermostat shoudn't be below 200F for a diesel engine and the reason why the CRD is operating so low is for emission reason (NOX ).

What is the best operating temp for our little diesel engine, what the thermostat value should be used for best fuel economy and power and reliability ?

papaindigo · **Posted:** Sun Oct 30, 2016 4:12 pm

Lots of bytes spilled on this topic. To the extent there is a consensus it's that the OEM tstat is on the "cold" side and that for the best operating efficiency a tstat that is 195-205F is probably better. However, don't confuse tstat temp with actual coolant temp. Tstat temp is the temp at which the tstat should start to open +- 3degress F per Stant. Actual coolant temp should be somewhat higher. Keep in mind that diesel engines run cooler that gas so they are sensitive to tstat malfunction. For example if, as is not uncommon, the KJ CRD OEM tstat starts to open too soon or fails open then the coolant will never reach operating temp.

Ceearedeedriver · **Joined:** Fri May 06, 2016 8:44 pm **Posts:** 177

PZKW108 wrote:

What is the engine operating temperature of the CRD R428 engine ? apparently the thermostat is 176F,
but when I got my OBD2 gadget plugged in with my phone and the torque pro app, it shows 167F.

I talked to a professional commercial diesel tuner about the CRD and he told me that you need 2600F on the top of the piston to make some good power. he said the thermostat shoudn't be below 200F for a diesel engine and the reason why the CRD is operating so low is for emission reason (NOX ).

What is the best operating temp for our little diesel engine, what the thermostat value should be used for best fuel economy and power and reliability ?

Hmm this is kind of embarrassing. In this thread here viewtopic.php?f=5&t=85143&p=896662#p896662

you told us "I have one of Jeff's themostat install in my Jeep for about 2 years now and Here in the very cold Canada, "

So what gives, are you reporting the first documented failure of Jeff's thermostat or are you just stirring shyte?

Does this professional commercial diesel tuner you speak of actually exist, Eh?

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

Ceearedeedriver wrote:

PZKW108 wrote:

What is the engine operating temperature of the CRD R428 engine ? apparently the thermostat is 176F,
but when I got my OBD2 gadget plugged in with my phone and the torque pro app, it shows 167F.

I talked to a professional commercial diesel tuner about the CRD and he told me that you need 2600F on the top of the piston to make some good power. he said the thermostat shoudn't be below 200F for a diesel engine and the reason why the CRD is operating so low is for emission reason (NOX ).

What is the best operating temp for our little diesel engine, what the thermostat value should be used for best fuel economy and power and reliability ?

Hmm this is kind of embarrassing. In this thread here viewtopic.php?f=5&t=85143&p=896662#p896662

you told us "I have one of Jeff's themostat install in my Jeep for about 2 years now and Here in the very cold Canada, "

So what gives, are you reporting the first documented failure of Jeff's thermostat or are you just stirring shyte?

Does this professional commercial diesel tuner you speak of actually exist, Eh?

I just want to know what is the best operating temp, I have Jeff's thermostat in my wife's CRD and will do more testing on this one as well ( if I can borrow it......lol )

And by the way Jeff doesn't make thermostat he makes thermostat housing....... if the thermostat fail, then you can change it.........

I think the one stirring doo doo here. If you don't have nothing to bring to this tread refrain from posting.

flash7210 · **Posted:** Sun Oct 30, 2016 7:15 pm

The manufacturer seems to think that a 176 F thermostat is whats best for this engine. How they decided on that temp I dont know.
If you want a hotter thermostat, thats for you to figure out which is best.
It really depends on your driving conditions.
A 203F thermostat might work great in the winter.
But it you operate in Arizona during the summer, driving up steep mountains, or towing heavy loads, a cooler thermostat might be better.

BTW, just because your thermostat opens at 176F doesnt mean your engine wont get up to 195.
Push your engine hard under the right conditions and it will easily get above 200.

Edit:
Just for comparison, a 2005 Dodge Ram Cummuns came with a 190F thermostat.

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

flash7210 wrote:

The manufacturer seems to think that a 176 F thermostat is whats best for this engine. How they decided on that temp I dont know.
If you want a hotter thermostat, thats for you to figure out which is best.
It really depends on your driving conditions.
A 203F thermostat might work great in the winter.
But it you operate in Arizona during the summer, driving up steep mountains, or towing heavy loads, a cooler thermostat might be better.

BTW, just because your thermostat opens at 176F doesnt mean your engine wont get up to 195.
Push your engine hard under the right conditions and it will easily get above 200.

Edit:
Just for comparison, a 2005 Dodge Ram Cummuns came with a 190F thermostat.

I just got my torque pro app, I haven't get much data yet .

What temperature is consider overheating ????

geordi · **Posted:** Sun Oct 30, 2016 8:26 pm

As far as what your diesel tuner friend suggested, they are out of their minds.

This engine and most other diesels have aluminum pistons and an aluminum cylinder head. A temperature of 2600 degrees even for milliseconds will melt the pistons because that temperature will be happening repeatedly with very short durations of heat and cold in the combustion chamber.

Heavy diesel trucks have the red zone on the pyrometer at 1200 degrees, and there are people with melted pistons as souvenirs that was only running 1200-1350 over a pass in Montana. Oil jets will cool the piston down and lower the thermal inertia, but aluminum still wants to melt around 1200-1300 degrees. You can't have combustion twice and then some higher than that, and expect to have it last AT ALL.

We are having valve stem failures that we don't know what the alloy is yet... But the UPRATED alloy choice from Manley or Ferrara (better than stock and more money) topped out at 1300 degrees cylinder temps. Obviously there is never supposed to be temperatures that high within the CRD cylinder, because the engine just cannot handle it.

For coolant temperatures, the computer will cut fueling after cutting the A/C out, if the temperature rises above 230, I believe fuel cut is at 234 degrees.

Anything above 215, I would be concerned.

flash7210 · **Posted:** Sun Oct 30, 2016 8:30 pm

I think 240 is considered overheating.
But if you ask me, 225 is too hot.

WWDiesel · **Posted:** Sun Oct 30, 2016 8:51 pm

geordi is dead on, any temperatures exiting the combustion chamber and entering the turbocharger greater than 1200-1300 deg.s F for extended periods can and will do irreparable damage to the pistons. They are aluminum and can only withstand those high temperatures for very short periods of time!!!
Your tuner friend is incorrect!!! :shock:

geordi · **Posted:** Sun Oct 30, 2016 9:28 pm

I would advise against even 1200 degrees for anything more than a few seconds duration (such as a drag pull or bridge incline / entrance ramp) because you will heat-soak the piston and melt it VERY quickly.

For continuous operation, the upper limit I would suggest from a gauge mounted in the mouth of the turbo is no more than 1000 degrees. Post-turbo numbers should be about 300 degrees lower.

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

I might be wrong with the cylinder temperature I will have to ask again.

geordi · **Posted:** Sun Oct 30, 2016 10:57 pm

Interesting information here:

https://en.wikipedia.org/wiki/Hypereutectic_piston

I do not believe we have forged pistons. Based on the link however, we may have higher silicon content than a plain piston because our engines do not experience slap when cold, and the fit in the bore is not ultra-snug... But it is definitely well-fit. Minimal spacing exists around the piston when cold.

WWDiesel · **Posted:** Mon Oct 31, 2016 2:19 pm

Does anyone know if the VM pistons are cast or forged? Would make a difference on the EGT they could withstand....
I think most diesel pistons are forged, are they not?

flash7210 · **Posted:** Mon Oct 31, 2016 6:10 pm

The majority of small diesel engines use cast aluminum pistons.
In fact, just looking at a picture of one on idparts.com tells me they are cast.

Some large diesels use 2 piece pistons where the head is steel and the skirt is aluminum.

Engine operating temperature

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