thermostat/cooling system issues

[mcmud]

I have a 5ton that has suddenly developed a few leaks. Put maybe 1000 miles on it in the last few months with no issues to speak of and then a week ago it sprang four leaks in one afternoon drive. Started with the heater core, I bypassed that until i can fix it later. Then on on the right side of the engine, tightened the clamp. Two more on the rear of the engine just above the transmission, clamped those tighter too. So to my question, could a blocked or broken thermostat be causing this? If so, what is the part number for a good American made one? I also read that it could be a block somewhere else so i will try to flush the system today and see what that does. I don't notice any bubbles or steam anywhere else so I don't think it's a more serious issue yet, hoping to avoid that problem too!

 

[Suprman]

Which 5-ton? You have to check the hose clamps they do have a habit of working loose a little sometimes. Maybe the metal stretches a bit. A little snugging up here and there will usually fix that. Too tight you will break the clamp. Been there done that. Heater cores go bad. If your thermostat stayed closed you would probably know it pretty fast you would overheat.
Will

 

[mcmud]

It's the m923 a2. I've tightened the hose clamps as need be, the first few times that's what I assumed it was. The fan came on two or three times when I was not under heavy load and not on a hot day. Which leads me to think I may have a different problem

 

[Suprman]

There is a fanstat control on the upper radiator hose. When the coolant gets to a certain temp the fan comes on. It moves alot of air so generally it dosnt run for long before the coolant temp drops back down and the fan shuts off. If your thermostats (there are 2 on the A2) were stuck closed. Did you check the coolant overflow level?
Will

 

[mcmud]

Ya, that is still within normal ranges. Nothing seems to be coming from the over flow at all

 

[Suprman]

It cant hurt to do a coolant flush on your truck. There are several gaskets needed for a thermostats swap. I was planning on doing it myself the only one who had most of the stuff was the Cummins dealer and it wasnt cheap.

 

[bchauvette]

see:
http://www.steelsoldiers.com/showthread.php?126734-Cummins-NHC250-thermostat-change&highlight=

 

[Suprman]

His is the 8.3

 

[mcmud]

I found the thermostat at Kragen for $8 for that size engine. All I would need, from I was told, was the main gasket that fits in between the two pieces that lock the thermostat in. That's just what I was told from a mechanic friend

 

[Suprman]

I hear the TM calling your name