Re: C8.3 Water filter shut off valve broken
Reply #25 –
Finally got everything back together, coolant flushed, filled, and 40 mile test run in 96 degree heat.
Somehow I ordered the old nylon valve instead of the stainless. Even though they recommend replacement of the nylon valve with a stainless valve, they still manufacture and stock the nylon valve. The price differential is about $60. We gouged the valve bore in the thermostat housing removing the stuck coolant valve and I opted to use the nylon valve hoping it was more forgiving. The o ring was a real stretch to get onto the shaft, but it sealed the housing and no leaks so far.
I used the factory gaskets without gasket sealant. The internet wisdom is absolutely contradictory on sealant/no sealant. I saw no evidence of sealant when cleaning the gaskets off. My engine manual did not suggest sealant when replacing the thermostat, so I torqued to recommended levels and they appear to be well sealed so far.
The old thermostat seal (not gasket, but metal seal with rubber trim) was difficult to remove. Used seal remover from Harbor Freight and it took many attempts to pry out. After several attempts to install new seal, I realized it is simply placed around new thermostat and it seats itself when you assemble the housing to the block.
My engine manual showed the two thermostat housing. My housing, called a bypass housing, has only one. There was no valve to release air on the housing as shown in the manual or as indicated with a sticker on the engine. Instead, there was a line from the bypass housing and thermostat housing that ran to the coolant fill tank. Two lines total. I believe they provide a means for air to escape so my particular engine "bleeds off air" into the coolant housing.
I changed from the traditional green coolant with added SCAs to Fleetguard OAT. The Cummins dealership uses NOAT in all their engines, I special ordered OAT. I followed the procedure recommended by Wolfe with initial drain, flush with filtered tap water, ran at fast idle with heater on low to thermostat opening temperature, drained, filled with distilled, ran engine twenty miles, let engine cool, filled with distilled, drove 20 miles and had a brief scare as temperature jumped to 220 and then dropped 30 seconds later to about 100 and then stabilized at 185. I'm assuming that was a big air burp. Drained and cooled engine over night, filled with 7 1/2 gallons of concentrated OAT next day and then topped off with distilled water.
Test run this evening was about 40 miles in 96 degree weather, 65 miles per hour. Thermostat ran to 180/5 and then held for the entire run. My last trip before changing thermostat had seen erratic temperature mainly from 185 to 220 and average around 200. Before that trip it had run 180 to 200. Since owning, I've never seen the steady 180/5 that showed up after my change of thermostat. It was time to beak out the champagne.
My system holds approximately 15 gallons according to my Foretravel manual. I used 30 gallons of distilled water in flush and fill. I've got about 15 gallons of antifreeze to recycle. It took me at least two full days to flush and fill, not counting recycling or dealing with thermostat and housing. The location of my coolant tank makes it virtually impossible to use a funnel. I poured coolant into the tank with a small plastic cup, 5 ounces a shot. I used my fresh water fill pump running slow to fill the distilled water into the tank.
Concluding thoughts: I know my cooling system better. I understand why the local Cummins shop doesn't like working on motor homes. One C8.3 in one application isn't like another C8.3. At some point after reading everything you can find on the forum, in the manual, and online, you have to look at your coach and figure out what "is" rather than what "ought to be." My wife always says to multiply my estimate for how long something will take by four and then double it. She is usually right.
Thanks for your help.
Topic: C8.3 Water filter shut off valve broken