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Thread: coolant change, thermostat change

  1. #1
    Join Date
    May 2015
    Location
    socal
    Posts
    4

    Default coolant change, thermostat change

    In my persuit to bring my trucks service up to date, 95 6.5 td chev 3/4ton auto 2wd. I was going drain and flush the cooling system. I had checked the antifreeze and found it in good color, but it was good to -5F. I also found the thermostat gasket seeping, so I wanted to change it and thermostat check for proper temp opening of 195F. Since I also had valve cover leaks, and oil n the hoses, I wanted to change anything swollen by oil. I had changed the valve cover gaskets at my oil change. So there are no new leaks of oil. I looked up the cooling system capicity, which is 26.5 qt. I got out 2- 5 gal buckets, expecting to near fill them with the antifreeze. I opened a hole under the drain and ran a hose to it into the bucket. I also removed the coolant reservor lower hose at the top of the radiator, and the lower radiator heater hose at the "t". Too long here, but after opening any hose end, in the hopes that I could remove all 26.5(+/-), I could only get 3.5gal out. I looked as many places on the block as was humanly possible to look, but no engine block drain. As a byline, I had no overheat, or antifreeze leaks before this. No stiff pressureized hoses. Had good cabin heat. The coolant rez was full. The only questionable thing was a dash light that would only come on when I put a small trailer on the hitch. Low coolant. I cked for bubbles in the rez, but none. The temp was normal. I "assumed" that the sensor was in question since there has always been full rez. The truck has 144k miles, has very little blow by, and isa strong motor. No oil water, water oil. Going to have oil analysis before nest oil change. The only other possibility is a blockage either in the radiator, which unfortunatly cant be checke, that I know of, sinct gm didnt put a place on the radiator for a fill cap to open and watch for the circulating coolant when the thermostat opens. Kinda long toothed here in my description, but I'm
    Wanting the thinking heads out here to have the most complete observations to help trouble shoot this. I noted one other thing, as I buttoned up, with all hoses replaced, and new thermostat, which I decided to change to 180F. I stardes, bled the air from the system after adding the 2.5 gal of new antifreeze, as well as wetter. Started, idled it til the thermostat opened, bled it again, cked for leaks, pressured hoses. Drove it down the street and back. Ched hoses again, and the only issue I noted was the heater hose fro the cabin torad seemed pressurized. There was a little heat in the cab, but not much. That was noticed before I started this journey, only very recient, which is why the flush etc. Might be a partially blocked heater core? Anyway, these are my notes, I'll keep these on here in hopes that either I, or you members will see something I misse. Another note, in the drain down of the system, I did remove heater core hoses to drain, and blocked different orifaces and forced air thru the rad, core, block, wherever I could to get the illusive "26.5 gal" of antitreeze.

  2. #2
    Join Date
    May 2015
    Location
    socal
    Posts
    4

    Default coolant system change

    Another note. I havent cked the coolant rez pressure cap for proper pressure release. The rez is over the "full cold" mark. Sure would like to find out if the waterpump is fully circulating coolant thru the system. Im going th splice a pressure guage inline the heater hose. Heater mixing valve.

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