8V71 Thermostat replacement

[Fredward]

While I am rebuilding one of the radiators on the MC-5 (ouch $$$$$) I might as well replace the engine thermostats. Are there different thermostat temperatures for the DD8V71? Or is it just 190? If there are options what are they and why would I choose one over the other. I know the pistons aren't the right shape until about 180 degrees. But beyond that, what other considerations should I be aware of?
Fred

[luvrbus]

Fred, the thermostats range from 175 to 195 degrees I use 180 degrees in mine a 175 will give the minimum temperature operating range for a Detroit 2 stroke and always change the seals in the housing when changing thermostats.

I never heard of the piston thing except on a 3208 Cat engine    good luck

[Diesel_Gypsy]

Older Cummins engines were famous for scoring pistons/liners if you ran them hard when they were still cold. The theory was that their pistons weren't round until the engine was warm, therefore not enough clearance on the skirts. It may have been just marginal lubrication due to poor design or low quality oil. In any case this was never a problem with Detroits. In fact these 2-strokes blow so much air through them that they take a long time to warm up, so we usually hit the road as soon as the oil pressure evens out and the water temp comes off the pin, although I try to take it easy until the heat builds up some.

I would stay away from the 190 or 195 thermostats. If Detroit engines have a weak spot, it is that they don't like being overheated.

Later. . .
Jim

[pvcces]

Jim, while I agree that Detroits don't like being overheated, I believe that they don't like running cold, either.

When the Ketchikan International Airport was being built in the 70s, the contractor made a point of running the hottest thermostats that he could get for the Detroits. It made the teamsters antsy watching the temperature gauges climb to 200, but they got good reults doing this, according to some of the teamsters who were worried about the gauge readings.

One other benefit was lower fuel consumption because a hot diesel is more efficient than a cooler one.

In any case, unless a thermostat fails, I don't think that they contribute to overheating. All cool thermostats do is give some additional time before the engine is overheated when the cooling system is inadequate for the work that it is doing.

If the system is adequate, the engine will not overheat.

For what it's worth.

Tom Caffrey

[buswarrior]

thank you!

"All cool thermostats do is give some additional time before the engine is overheated when the cooling system is inadequate for the work that it is doing."

Pay attention, mythbusters and short cut takers.

Fix your rads, shrouds, seals, fans, plugged whatever. thermostats aren't your problem, and aren't your solution.

Mine came with 180 degree thermostats.

happy coaching!
buswarrior

[Fredward]

Thanks guys. I know I need to replace some of the gaskets that seal the radiator in the opening to direct air flow through the rad rather than around it!

Just as a preventative measure, if I do replace thermostats while its all drained down, do you know if I need to remove the exhaust crossover pipe on the 8V71 to do it?