Paccar Gremlins; Pushing Coolant Out Overflow; Not Overheating

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by fireball84, Mar 25, 2019.

  1. fireball84

    fireball84 Bobtail Member

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    Mar 25, 2019
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    Hey guys, just a heads up, this will be a bit lengthy. I want to try and include as much detail as possible. I drive a 2012 Peterbilt 386 with a Paccar in it. It is a new addition to the fleet. This engine has had the DEF system deleted and the engine has been tuned with a 10% boost in HP. Before this was done, the head, head bolts and gasket were all replaced. A couple weeks later while I am out on the road, the low coolant light, check engine light, and stop engine light come on. I added some water, unloaded and went on about my way. The next day after I got loaded again and back on the road, all three lights come back on again. I stop and check and sure enough, coolant is below the min line on the reservoir. The coolant was being lost through the coolant overflow hose. I fought with this, stopping every 30-45 minutes and adding 1/4 to 1/2 gallon of water. The engine never did run hot, with the hottest it ever got being a hair over 200. I never could get it to act up while sitting at an idle, even while idling at higher RPM's. I wound up passing by a KW dealer, stopped and got a new RAD cap. This did not solve the issue. I eventually made it to my destination and unloaded. Truck idled all night, again never once acted up. I drove the truck home, 13 hours on the road, empty, with the engine fan on manual, and it never once acted up. Truck went straight to the shop. Three weeks later, it comes out with a clean bill of health. New head, head bolts, and gasket. Old head bolts were stretched to the point of being cracked. First day out, I run a local run, no hiccups. Second day, the truck got to stretch it's legs a little. It did fine, until I reached the interstate and hit 70+mph. Low and behold it started doing the same thing. Fought it all the way to Lebanon, Tn, stopping every half hour to hour and adding more water. Loaded the truck the next day, drove it back home, this time setting the cruise to 63 & engine fan to manual, but still loaded, and it only acted up two times, each time when I pulled into a parking lot and turned the engine fan off. I also noticed during this second round that when I remove the rad cap and the pressure releases, the coolant level in the reservoir rises about a quarter of an inch. One other thing I also tried, is loosely screwing the RAD cap on, but all this did was cause it to blow coolant out around the cap.
     
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  3. JohnC123

    JohnC123 Light Load Member

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    Jan 25, 2018
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    Seen this and lived it. Does it regen good (complete, i.e. Davie) and the coolant is still the original red color? because that will eliminate the egr cooler (inspect rear cooler pipe if unsure, should be sooty DRY). An air compressor head kit is not cheap but a common failure point (smoke white a little bit under load) but in my case (same scenario as yours), the head was cracked (ran like a champ, perfect) and the event could not be duplicated parked at any rpm unless trailer on and loaded. Injector cups would be symptomatic also but you would have starting issues (none with mine) and fuel would be present in the coolant (does not mix, check for layers come morning time)(piston liner fire ring/lip cracked maybe). temp was never hot....new water pump/thermostat, egr cooler, fan clutch, surge tank and compressor head. Head was cracked, opens under load...
     
  4. JohnC123

    JohnC123 Light Load Member

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    Jan 25, 2018
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    Also forgot to mention head gasket (possible/probable), just re-living my bad luck, thanks.
     
  5. JohnC123

    JohnC123 Light Load Member

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    Jan 25, 2018
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    again my bad on your delete, symptoms are the same, thanks.
     
  6. spsauerland

    spsauerland Road Train Member

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    I posted one awhile back with a cracked liner. Anything is possible.
     
  7. x1Heavy

    x1Heavy Road Train Member

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    White County, Arkansas
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    I had one that refused to cool properly, spill a bit of coolant etc. We finally had a powwow next to that POS truck in the big shop. One of the options was to junk it. When 10 mechanics and several really big experienced wigs ask me the sequence of behavior until shutdown overheat etc the story is the same, when asked 6 different ways it still came out the same.

    In the big silence before the boss top makes his final decision to either scrap the truck or fix it somehow I remembered one of my cars that did the exact thing. Until the old worn out radiator cap was shown to be bad. We pulled the cap off that thing and tested it. It's supposed to hold 15 PSI it failed at 3. New cap and all is well. Its the one little procedure not yet done to that poor truck.
     
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  8. t turpin

    t turpin Bobtail Member

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    Nov 26, 2020
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  9. t turpin

    t turpin Bobtail Member

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    Nov 26, 2020
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    so what was the final fix ?
     
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