Looking for some information, if I may. I think I have a failed t'stat as I can't get the ECT over 174 even after driving at highway speeds for 3 hours with an ambient outside temp of about 50. I have good heat in the cab. Is there any downside of leaving this t'stat in place as opposed to changing out ?. I will change it but this is just a "for my own curiosity" type question.

Thanx

Peter

 

I doubt you're hurting the engine any. You would probably operate a little more efficiently with a new thermostat. The colder the engine the more likely it is that some of the fuel isn't going to burn completely.

Also, if you're wanting to watch for the minimum 15 degree coolant/oil temperature differential, you need the engine to run at the proper temp. Otherwise the comparison is invalid.

 

Thanx Dave. Kinda what I thought. The Insight reads wacky stuff when the ECT is that low but the greatest delta I've seen is about 11 degrees. Gonna wrench on it tomorrow. I would also guess that fuel economy would be affected by the low ECT's as the engine is not running as efficiently as it could.

 

Absolutely. A diesel engine has no spark plugs and therefor relies on heat and compression for combustion and efficiency.

 

I guess that would explain the drop in fuel economy I've noticed. With fuel in my area at $3.38, have to squeeze out every yard of mileage. It might also explain why my mileage towing is not all that different from normal highway driving. The ECT's shoot up to about 200* when towing and therefore make the engine more efficient, yes ? Thanx all for the info.

Peter

 

It'll coke up a lot faster.

 

Is there any benefit to having a slightly lower T-stat for summer driving. Here in florida right now the t-stat opens at 195 and hovers about 197 with EOT at about 201 fluctuating a couple degrees as the load and traffic changes. Seeing its cooler now, is there a different temp to lower the ECT say five or so degrees that could be used in dead of summer? I know that towing the boat and driving 65 in August here, the ECT is going to go much higher and so will EOT. And if its better to lower under hood temps, do they make such a thermostat for an 06?

thanks

 

I don't see a benefit to running a lower temperature thermostat. I ran through Hoover Dam and Vegas last year with the outside temperature at 115 degree's and didn't get much over 215, even climbing some pretty serious hills. The thermostat isn't even fully open until 219. The truck is designed to handle temperatures much higher than those.

 

At least yours has one in. I went to do the coolant flush 2 weeks ago and check the t'stat because my truck would never get warm. So we take off the housing and...NO t'stat. There's yer problem!

 

We are long past the days when "optional" thermostats gave us a measure of control over issues as overheating.

These days, engines are so tightly regulated temperature wise (for emissions and other reasons) that there is not much wiggle room --- unless you can get at the software.

I seriously wonder if there is software that programs for more fuel at colder temps to speed up the warm up, because I cannot completely explain my lower mileage from just the use of winter blend.

 

My t-stat was a part of the housing. I could NOT run without one. (and would not)

The number one cause of early failure in a diesel engine is lack of letting them get to full operating temp. I just read that somewhere, and my t-stat was a little week, (175ish) so I changed it. not a big job at all. while I had the coolant out, I ran it all through a 3 micron filter I had ( I have several from work, used in Pulmonary function testing). I did notice a slight jump in MPGs.

 

Please see proper coolant flush / VC-9 threads in tech folder...

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Suppose you are a software writer for the diesel.

You want a routine that helps them built heat / get up to operating temperature as fast as possible in extreme cold.

How would you do it?


There is known to be a "high idle" routine when it is stationary.

Would you vary injection volume / timing?

What about a routine that injects more fuel per unit throttle command (assuming poorer combustion efficiency at cold temps) ?

That will also give the impression of better throttle response even if the unburnt fuel goes out the tail pipe or becomes coke.

Or maybe a bit of fuel injected later (to burn rather than to make power) to heat the motor?

I know the 6.0 is a split charge (2 charges), but the later injectors can do multiple charges.

On the 6.7, they can basically inject fuel during the exhaust cycle (to be used as fuel to heat the DPF).

How would the software be written...

I would love to see the source code.


Sometimes, you can find hints to undocumented features via their technical presentations, braggings (like they did about how the knock was taken out of the 6.0 / 6.4 / 6.7), or as gossip.

 

I was not flushing or replacing coolant, just the T-stat.

 

one of the main reasons that diesels do not heat up until underload is the same reason that you have a diesel in the first place.
They are very efficient. and do not produce a lot of waste heat.

 

I can tell you from personal experience that there are different levels of fuel at different temperatures. My truck changes from Dr. Jekel to Mr. Hyde at about 179*F ECT and about 160* EOT. Now it may just be from the programming on my truck, but temps definitely make a difference. I've already noticed an improvement in my fuel mileage since installing a correctly operating thermostat, even with extended warmup times from cooler than normal temps in my area.