Found it.

well... found a problem anyway... HOPE this is the crux of the issue. Radiator drivers side tank is cracked. It's a "veiny" kinda crack... soon as it builds pressure, she starts seeping pretty good. I think I'm going to drain, pull, clean (sand), jbweld, and hope for the best. :)

Thanks for all the help and support through this.

I did run a couple bottles of the prestone super duper cleaner in it for about 8 hours, and backflushed 20 mins at a time for 3 iterations... still some residue in the hoses I noticed.. but all in all, pretty clean.

Hey Ole buddy, glad to see ya still visit when ya have problems.:ouch::madd:

The crack would explain bein low but not the gunk. I'm bettin the brown gunk is the result of somebody pourin in the wrong kind of coolant. Our coolant is not compatible with some others out there. With just the wrong mix it can turn hard and stop flow completely. An oil change shop did this to me once, poured in the wrong stuff and it turned all the coolant into a gel kinda stuff.

:ph:OH MAN! I knew you'd come along and bust me!!!! lol.

Hey, it's nice to be remembered! :pals:

Yeah man. I love the ol gal, my attention just turned to motorcycles, so I spend my free time BOMB'ing them.

cross your fingers that the jb weld works! :w2:

Hey Andy- Also if someone has mixed two kinds of antifreeze a lot of times after a while they will gum up due to different compounds and it really looks like number 2! Flush and drain the system after you get you leak fixed.

Updarte of sorts... Found a decent radiator shop here local. They hottanked, pressure tested, and replaced the cracked tank for $90. Did a great job too.

It's all buttoned back up, and have driven 50 miles or so... issue now appears to be that it never gets over 180*'s. WTH?

I put around 5 gals of 50/50 in it, and a new CUMMINS tstat (185*).

I don't think it's a bad waterpump, b/c it's got to be circulating to keep the temp down that low... and I'd think 5+ gallons of coolant would be enough to keep the temp sensor submerged (therefore the readings are correct). so I'm kinda wonderin' if the tstat is rated too high??

I like the 190 stat myself............keep the oil hot and flashin

Interestin'.... I just went into the local Cummins place... my usual dudes weren't there, and I got the pleasure of dealing with the resident neanderthal. Knowing anything out of the ordinary would throw him off and I would likely end up with the wrong part... I just gave him my ESN and asked for a tstat. He brought me a 185 and charged me $38. I really don't like that guy. lol.

yer better off with a 190

Dangit!!!! grumble grumble grumble.... :argh:

I'll get one.

You can test your thermometer on your stove while wife is out. Put a candy thermometer (remember she must be out!) in water heat up slowly to around 180 degrees - thermostat should stay nearly closed - begin slight heating and raise the temperature and it should open really soon after heating more. If it is opening sooner you will be running cool temps and it is time for a replacement. A cool trick to set your temp is to buy a higher than you want temperature thermostat say a 195. Drill an 1/8th in hole in it and it will bypass 1/8 in hole worth of coolant through the system constantly and here's the kicker - every 1/8 in hole you drill will lower the running temps 10 degrees. So one hole on a 195 thermostat would be 185 degrees. Don't put bigger than 1/8th holes but you can put up to 4 holes. Smaller change needed? Drill smaller hole and see where ends up. Too much thinking on this as far as hole sizes will cause you to ask for therapy. You must start with a higher than needed temp on thermostat to make it work. BTW I tested 3 different thermostats on my motorhome and all three were off on what they were rated until I adjusted them where I wanted them. After done with candy thermometer clean up really well and put back where you found it BEFORE she gets home surely you will suffer. Good luck my friend. Lastly - bad water pump will overheat not excessive cool.