Running too cool

[Ron4104]

We have a 4104 repowered with 8V-71 & V730 allison. If the outside temp. is above 65 degrees the engine runs at 170 degrees. Below 65 it starts running cooler. Took it to a friends house this morning, outside temp about 40 degrees and engine temp only got up to 140 degrees. I know these buses used to have shutters when they were new, but we have owned it since 1995 and the shutters were removed before that. I put a larger radiator in when we did the transplant so it would not run too hot. At 90 degrees outside it runs 170 on the flat and does not overheat climbing normal hills. Problem seems to be in cold weather it won't get hot enough. any and all ideas welcome.  Thanks. P.S. Reason I took the bus to the friends house was to remove a leaking fuel tank. Boy we had fun removing 50 plus years of crud.   Ron 4104, SINGING FARMER

[artvonne]

 
  Check the radiator for temp. If its warm when the engine is at only 140F I would check the T stat to see if its stuck open. If it does check out, you could block the radiator. But make darn sure you watch the temp. Cold isnt good, but boiling over is worse.

[TomC]

I would replace both thermostats with new 170 or 180 degree.  Not very expensive-sounds like one of the thermostats is stuck open.  Good Luck, TomC

[luvrbus]

If the thermostat seals are bad inside the housing it will let the water bypass the thermostats and the thermostats do no good fwiw

good luck

[RnMAdventures]

What are the consequences of allowing to run cooler?

[artvonne]

What are the consequences of allowing to run cooler?

  140F isnt necessarily bad, inboard boat engines have 140F thermostats to keep the motor below the flash point of gasoline. But running a bit hotter is more efficient and burns off water and contaminents faster and better. But if I had to pick, id rather run 140 than 210.

  Any colder could become a problem running that way long term. The pistons may not swell to fill the cylinder properly, leading to thrust face wear and eventually piston slap. Cold could also build up deposits in the ring lands, coupled with piston slap, etc, might not live as long.

  Optimum is 170-180.

[thomasinnv]

i would think a diesel engine you don't want running that cool. probably not getting very efficient fuel burn at that temp, and the pistons and rings would most likely be a little tighter at 170-180 creating less oil consumption. Just an opinion, not necessarily fact.

[gus]

My 4104 w/671 did the same thing until I got ter shutters working.

A cardboard cover is a good idea, easy to change. You can cut the hole on three sides to make a flap to allow changing the size. Be sure to open it at the center.

[robertglines1]

Have found that my allison shifts better when the engine/transmission temp is up in the 185 engine temp range. Just a observation.   Bob

[Ron4104]

Thanks everyone. Think I'll change the themostats and go from there. Ron 4104