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Any body that's worked on a pusher RV probably knows how big of a pain in the arse they are to work on. Anyway I had a doozy of a time diagnosing a major coolant leak on a 2012 Cummins ISC with 46,000 miles today with only having a 2 foot by 2 foot hole in the floor in the bathroom to access the top of the engine. I started off by applying air pressure to the radiator with a pressure tester. The system of course would not hold pressure and air leaking very audibly somewhere on top of the engine. I removed the EGR cooler and pressure tested in a tub of water. A crack in the EGR cooler case was found doing the pressure test. I installed a new Cummins updated EGR cooler and pressure tested again. System held 15 lbs of air pressure for over an hour. I filled the cooling system with fresh Red Extended Life coolant and started the engine. All was well until about 150 degrees and I had a river of cherry Kool aid coming out again. I shut down the engine and pressurized the cooling system which again was not holding pressure. Could again hear air leaking at the top end of the engine. My worst fear was a head gasket. I removed the EGR cooler again and rigged up the cooling system plumbing to by-pass the EGR cooler and applied air pressure to the cooling system. What I found was two 7/8" expansion plugs leaking on the head. The best I can figure is poorly maintained cooling system caused the freeze plugs to start leaking since the max coolant temp the engine saw was 224*F so overheating was not the issue that caused the expansion plug failure. Hopefully Cummins will get me the plugs and exhaust manifold gaskets by tomorrow morning and the RV will be on the road on it's way to California.

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I understand what a Big, big pain.  I helped neighbor change just the valve cover gasket.  His wife also in pain watching us with our greasy hands in "her" bedroom.  We also pulled side radiator to clean it but not as bad as working under the bed.  

Wonder what Cummins would get for a head job?  Wonder if Cummins would require a signed waiver for getting stuff dirty?  Maybe even just drop motor to save the heartache?

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At least it's not a head gasket that would be a serious PITA. The head alone feel like a ton and difficult to handle even with two able body men or engine hoist and two men. Either way it not fun. Coolant lifespan is highly exaggerated. All these claims of 5 years and 100k miles. You better be changing coolant well before that. The problem is the coolant goes corrosive and starts eating metal and that is what causes the scale build up is the oxides in the water solidifying to the core tubes and such.  

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It's done. 16 hours labor total for the repair is what it took me. I'm not sure what a place that specializes in RV repair would have charged.

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Edited by 04Mach1

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