How hot is too hot

[Tikvah]

I'm going to install a new temperature sensor and gauge with an adjustable warning. 
What temperature is in the warning zone?
When should you pull over and cool the engine?
When is it too late?

[DoubleEagle]

Going by the Detroit Diesel Series 92 Field Maintenance Recommendations (6/88), the maximum temp is 210 degrees F. whether it is a 170 or 180 degree thermostat, with an alarm set of 215 degrees. The thermostat operating range is 170 to 197 degrees. Personally, I stop and cool, or reduce gears when it gets to 200. There are lots of opinions, but you risk damage when temps get over 200 and up for whatever amount of time it takes to ruin your particular seals.

[Utahclaimjumper]

 The worst thing you can do under those conditions is to pull over and let the engine IDLE, you need to go to neutral and bring the RPM up to increase oil pressure and fan speed and hold it there until the temps begin to decrease.>>>Dan

[Tikvah]

The worst thing you can do under those conditions is to pull over and let the engine IDLE, you need to go to neutral and bring the RPM up to increase oil pressure and fan speed and hold it there until the temps begin to decrease.

I didn't know that... that could be helpful.  I would have just left it idle slow and cool down slowly.
Seems the faster the engine speed the more heat it would produce.  Yes, more fan speed too, but there must be a point where it doesn't make sense?

Anyway, I'll try to remember that.  I have to pass over Jellico mountain today in 90 degree temps.  I'm going to unhook my toad and have my wife drive it.  But I'm still worried.

[Utahclaimjumper]

 What your missing here is LOAD, diesels make heat under LOAD, and very little is made without it. So remove the load and get the oil and water working for you, about 1000 to 1200 RPM and hold it there.>>>Dan

[DoubleEagle]

The fast idle setting is enough to cool it while stopped, but downshifting to the next lower gear (if the transmission does not do it for you) will reduce the load on the engine to let it catch up. Jellico is not as bad as it looks, but it is fairly long, third gear should do it. There will be plenty of loaded trucks slowing you down anyway, and you won't be carrying 57 passengers. 

[TomC]

What is Jellico-one of those little humps in the road on the east coast? Come out west for some real mountains (LOL)

[luvrbus]

Dave, not knowing the condition of your engine and how the cooling system has been maintained (antifreeze) I would pull over between 195* and 200* the spec's in a Detroit Field Service Manual are for new engines. 

A 92 series can go to hell in a hand basket in a hurry @ 205* if the cooling system has not been maintained the seals on the liners and head can turn to mush

good luck   

[Tikvah]

What is Jellico-one of those little humps in the road on the east coast? Come out west for some real mountains (LOL)

I've been driving my bus now for more than three years and more convinced than ever that these buses don't belong out west.  Every post about a blown engine seems to be in Montana or some God-forsaken mountain.
Jellico is too much for my bus without a toad or hell-type heat.  Today I'll go over during the night and let my wife drive the Tahoe.

[luvrbus]

LOL I drove my bus (8v92) all over the west for 15 years with no problems only break down was in the flat lands in Texas I broke a camshaft

[Oonrahnjay]

... Jellico is too much for my bus without a toad or hell-type heat.  Today I'll go over during the night and let my wife drive the Tahoe.  

     Weather Channel forecasts 81 degrees at 8PM and 71 at 10PM.  Are you going north?  Jellico grade is pretty steep for the East, and pretty long (ditto) -- probably the steepest on I-75 -- but it's not nearly as bad as I-77 at Fancy Gap (NC to VA, north of Winston-Salem and Mt. Airy "Mayberry").  Are you heading north or south?  There are good places to stop IIRC (been a few months since I did it with a 4-wheeler) so unhooking and re-hooking the Tahoo shouldn't be a problem.
     Drive it like you should and you'll be fine.  

[Tikvah]

We're headed south tonight.  Want to come push?   

[luvrbus]

Make you wonder how trucks got over the hill in the 50's and 60's with a trailer grossing 58,000 lbs with 190 to 220 hp engines   and the GM gas rigs with the 261 CI chev engine or the  270 CI GMC truck engine.My dad ran trucks (80,000 lbs) from Houston to Alaska for years with the almighty 250 hp Cummins engines loaded with oil field materials 

[Oonrahnjay]

We're headed south tonight.  Want to come push?    

    I'm already south but you'll have no trouble, elevation is about 1000 feet at the TN/KY border and it goes up to about 2000 but it takes 6 miles to do it near Newcomb.  Once you're at 2000 feet you run along without a lot of up and down until the grade down to Caryville (which is steep but you're going down it).
    Reason I asked about heading is that I know of campgrounds and truckstops in KY; unfortunately, I'm less familiar with TN.  There is an easy truckstop exit about 5 miles south of the border in TN at about 1970 feet, if you need a convenient, ez-off/ez-on cooling stop -- once you're there, the climb is mostly behind you.  Might not be a good place to rehitch the toad, you still have the downhill at Caryville to come.

[Utahclaimjumper]

 For crying out load, 2 thousand feet is like scratching your butt, I LIVE at 6 thousand and don't even notice till I start climbing.>>>Dan