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  • Rebuilt SR20 Running hot

    My SR20 is in the break in miles right now. I'm keeping it easy with the boost controller off. I noticed it was running much hotter than it used to. It used to hang around 180, since the rebuild it is running around 200 - 205 degrees. Could this be part of the break in? It has conventional oil to seat the rings. I normally run synthetic.

    The shop that did the rebuild had changed out my fan controller. I don't know why but the fans weren't kicking on. I rewired it and tested the fans, right to the battery they run no problem. After my rewire, they came on right when they should have. After driving around a while I stopped with the car running and checked the fans. They weren't running. The temps were OK so I just drove home. When I turned off the car, the fans were running like they should.
    Chicago Region SCCA SM # 688 http://www.scca-chicago.com
    TSSCC SM # 688 http://www.tsscc.org

  • #2
    Engines generally run a bit hotter during break in due to the higher friction on the rings and bearings and whatnot. keep an eye on oil pressure and water temp, but don't be real concerned unless the numbers go way out of whack.
    After a few hundred miles, your temps should drop as the rings seat and the overall friction inside the engine drops.
    Originally posted by SoSideways
    I don't care what color they are as long as they are LONG AND HARD.
    '04 G35 Sedan 6MT- The DD
    '96 240SX- The Track Toy

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    • #3
      Have you bled the coolant thoroughly? Typically it takes one good bleed(this does not take long), then drive it a bit, and bleed it again.

      Take out bleeder screw on coolant outlet, fill radiator until coolant comes out. Close up bleeder screw and fill up radiator all the way. Crank car up and let some bubbles get out of the motor while it's warming up. Top up radiator and close it off before it gets all the way up to temp.

      Drive it. Park, let it cool down for about 15-20 mins and then open the radiator and top it up. Crack the bleeder screw just to make sure there isn't any air trapped there(usually isn't). There you go, 99.999% bled cooling system. It's good practice to open the radiator every once in a while and top it up as well.
      '18 Chevrolet Volt - Electric fun hatch for DD duty!


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      • #4
        I left out of my original post that the shop missed a hose that had a pin hole burst when I originally overheated it. I replaced it when I got home and bled it after replacing the hose. Did a pretty thorough job. Luckily the hose didn't start pissing until I got home. I did notice the higher temps after replacing it.

        That makes sense that more fiction would have it running hotter. I'll watch the temp as it breaks in.

        Thanks for the replies!
        Chicago Region SCCA SM # 688 http://www.scca-chicago.com
        TSSCC SM # 688 http://www.tsscc.org

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        • #5
          agree with Def... sounds like you might have an air pocket in your coolant.

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          • #6
            Keep a close eye on it. Sometimes steel headgaskets are hard to seal but bleeding the air completely is very important and sometimes difficult. I have had to jack up the front of the car at times, while bleeding, to get the air out of the heater.

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            • #7
              Originally posted by gawdzilla View Post
              agree with Def... sounds like you might have an air pocket in your coolant.
              After owning and tracking the SR20DET I have a bunch of experiance with burping the cooling system. I'll do the process again if I don't notice a drop in temps after the break in period.
              Chicago Region SCCA SM # 688 http://www.scca-chicago.com
              TSSCC SM # 688 http://www.tsscc.org

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              • #8
                Maybe its the oil your using. A more fluid oil will absorb heat rather then create it when its running through the engines artheries.

                Is your syntec oil lighter then the mineral one you are using?

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                • #9
                  Lower viscosity oils will create less heat from friction and shear, but that "absorb vs create" dichotomy is all wrong.
                  ~1992 240SX, SR20/Koni track day car
                  ~2016 M3, daily driver

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                  • #10
                    I always noticed higher oil temps with thicker oil - which goes along with the more energy into shearing it.
                    '18 Chevrolet Volt - Electric fun hatch for DD duty!


                    DefSport Koni Sleeve and Spring Perch Buy!!!
                    http://www.nissanroadracing.com/showthread.php?t=5902

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                    • #11
                      you also lose power, but that's not a huge issue..
                      After I rebuilt my old Maxima engine, I filled it with 5w30 as I usually do. once I stopped on the way to a job and had the oil changed. the fcuktards put like 0w20 or something in it and I immediately noticed the engine revved easier and the oil pressure at redline was 20psi lower. my highway cruising water temps were also 10 deg lower.
                      Originally posted by SoSideways
                      I don't care what color they are as long as they are LONG AND HARD.
                      '04 G35 Sedan 6MT- The DD
                      '96 240SX- The Track Toy

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                      • #12
                        Resolution. The shop forgot to change the thermostat when they did the rebuild. They changed it out and temps are back to normal. There was also a clamp that wasn't right on the coolant hose to the Throttle Body that caused a small leak. That is replaced.
                        Chicago Region SCCA SM # 688 http://www.scca-chicago.com
                        TSSCC SM # 688 http://www.tsscc.org

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                        • #13
                          Sounds like an "awesome" shop. Or really busy.

                          Glad you found the source!

                          ~Alex

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                          • #14
                            I brought it back to the shop to get the head studs checked (re tourqed) and told them about it running hotter. They found it and didn't charge me so no harm done. All in all they did a good job, there were some minor mistakes and delays but nothing major and they compensated me with discounts. I'd go back to them in the future.
                            Chicago Region SCCA SM # 688 http://www.scca-chicago.com
                            TSSCC SM # 688 http://www.tsscc.org

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