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  #16  
Old 12-30-2013, 09:43 PM
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Originally Posted by Brian Carlton View Post
When I worked for Chrysler, they had a Diplomat running at 235F. with a high pressure cooling system. It got about 15% better fuel economy than the standard vehicle.

Never decided to go forward with a prototype vehicle because of durability and maintenance issues.

Suffice it to say...........the warmer you run the engine, the better the fuel economy.
This relates exactly to the lower mgp's I've been getting since winter started. I'm pretty sure my thermostat is partially stuck open. Last summer I only had to fill up about once every 4 weeks. At that time, I was reaching 85 degrees every time I was driving in the city. Since winter, I've been averaging about 75 degrees and have to fill up about every three weeks now.

I'm a constant gauge checker and last summer I always maintained 85 to 90 degree coolant temp on the interstate but this winter, I can only max at 85 and when I go from 80 mph in the interstate to 60 on back roads, it quickly drops to about 75 degrees, sometimes down to 70 (ambient temps of about 50).

I have a new 85 degree Behr thermostat and am about to install it with some zerex. I'll let ya'll know what effect this has on MPG. FWIW, I thought my temp gauge was inaccurate so I hit the thermostat housing with the IR gun and it was close to the gauge temp, then I ohm'd the temp sensor on the head and it matched the gauge so I know the gauge is reading correctly.

Willson,
85 300CD

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  #17  
Old 12-30-2013, 11:00 PM
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Quote:
Originally Posted by Waste_Gate View Post
This relates exactly to the lower mgp's I've been getting since winter started. I'm pretty sure my thermostat is partially stuck open. Last summer I only had to fill up about once every 4 weeks. At that time, I was reaching 85 degrees every time I was driving in the city. Since winter, I've been averaging about 75 degrees and have to fill up about every three weeks now.

I'm a constant gauge checker and last summer I always maintained 85 to 90 degree coolant temp on the interstate but this winter, I can only max at 85 and when I go from 80 mph in the interstate to 60 on back roads, it quickly drops to about 75 degrees, sometimes down to 70 (ambient temps of about 50).

I have a new 85 degree Behr thermostat and am about to install it with some zerex. I'll let ya'll know what effect this has on MPG. FWIW, I thought my temp gauge was inaccurate so I hit the thermostat housing with the IR gun and it was close to the gauge temp, then I ohm'd the temp sensor on the head and it matched the gauge so I know the gauge is reading correctly.

Willson,
85 300CD
I would test the thermostat before installation.
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  #18  
Old 12-30-2013, 11:39 PM
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Originally Posted by Josh8loop View Post
Good input-thanks! I'm some what unfamiliar with the clutch fan operating characteistics so that helped too. Glad to see you didn't mention anything related to increased engine wear from the elevated temps-must not be a weak area of this particular engine. I'm kind of concerned about head warpage and head gasket failure. Not sure if that has been a major issue with these engines either? Thanks again!



..
I can't speak to the turbo version, but the naturally aspirated version of the same engine ('97) has had a problem with head gasket coolant leaks to the outside. I doubt if 10 degrees hotter temps would have much effect, but the long aluminum head on the iron block seems to stress the head gasket at normal operating temperatures.
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  #19  
Old 12-31-2013, 12:41 AM
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Make sure you get a good coolant for diesels that has a higher boiling point as well, like Pentofrost NF.

Phil Forrest
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  #20  
Old 12-31-2013, 08:10 AM
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Quote:
Specifically, do the 1999 E300D engines have piston skirt oil jets for piston cooling?
yes

I am of the opinion that you can run it as hot as you want as long as cooling system is pressurized as needed and you keep the egt below what it takes to melt a piston.
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  #21  
Old 12-31-2013, 09:21 AM
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I definately plan on testing the thermostat before installing. And its actually an 80 degree t-stat. Isn't that what most people normaly use on the turbo OM617?
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  #22  
Old 12-31-2013, 10:26 AM
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Quote:
Originally Posted by Waste_Gate View Post
This relates exactly to the lower mgp's I've been getting since winter started. I'm pretty sure my thermostat is partially stuck open. Last summer I only had to fill up about once every 4 weeks. At that time, I was reaching 85 degrees every time I was driving in the city. Since winter, I've been averaging about 75 degrees and have to fill up about every three weeks now.

I'm a constant gauge checker and last summer I always maintained 85 to 90 degree coolant temp on the interstate but this winter, I can only max at 85 and when I go from 80 mph in the interstate to 60 on back roads, it quickly drops to about 75 degrees, sometimes down to 70 (ambient temps of about 50).

I have a new 85 degree Behr thermostat and am about to install it with some zerex. I'll let ya'll know what effect this has on MPG. FWIW, I thought my temp gauge was inaccurate so I hit the thermostat housing with the IR gun and it was close to the gauge temp, then I ohm'd the temp sensor on the head and it matched the gauge so I know the gauge is reading correctly.

Willson,
85 300CD
another issue with winter fuel economy is the fuel itself has less energy in the winter mix...

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