Pete M Posted October 15 Share Posted October 15 1 minute ago, derf said: He put in a lower temp thermostat so in theory it shouldn't run that hot. thermostat doesn't control the upper range, only the lower range. Link to comment Share on other sites More sharing options...
Airborne Janitor Posted October 15 Author Share Posted October 15 Water pump was replaced 7 years ago. I am contemplating getting a flowkooler replacement, I've been running one in my XJ for years with good luck. I need to get my temp gun to confirm temps, but I drove this truck last year without issues until the head gasket started leaking.... I'm running 3.55 years with 33s which sucks but is doable, I have 4.56s in a box which I'm going to install once I fix this overheating issue. I'm going to try burping the system again at the temp sensor in a bit. Link to comment Share on other sites More sharing options...
derf Posted October 15 Share Posted October 15 2 hours ago, Pete M said: thermostat doesn't control the upper range, only the lower range. Sure, but an engine should get to an upper limit above the thermostat rating and stay there for the most part. If you're getting to 240° something else is wrong. It's one of a couple of thing. 1. Corrosion inside the block that prevents heat transfer to the coolant mix. 2. Corrosion or sediment in the radiator preventing heat transfer to the air. 3. Insufficient water flow. 4. Insufficient air flow. 5. Too much heat being generated by the engine for the cooling system to handle. #5 usually happens when you add forced injection to a naturally aspirated engine, but also can happen working then engine hard (possibly when its running lean). Link to comment Share on other sites More sharing options...
Airborne Janitor Posted October 16 Author Share Posted October 16 So on the drive home tonight I took the state roads, average 50-55mph. Stayed right under 210* unless I was stopped at a light, then it would go to 210, then drop back down on acceleration. I bled the air at the temp sensor tonight, the truck ran right around 185-190* for 30 mins. After turning her off and tightening the sensor, I turned the vehicle back on and the gauge was at 230*, then dropped down after a few mins. Will grab my temp sensor tomorrow and report back. Link to comment Share on other sites More sharing options...
derf Posted October 16 Share Posted October 16 You will get higher temps shortly after shutting down. The coolant will soak in residual heat and spike a little. As soon as you start it running again the pump will push cooler water through and should bring it back down in short order. So I wouldn't worry too much about that. Focus on temps while driving and idling. Link to comment Share on other sites More sharing options...
Airborne Janitor Posted October 19 Author Share Posted October 19 Took her out on the highway for a bit today, stayed pretty cool around 190-200. But as soon as I pulled off the highway and stopped at a light the temps would rise back into the 220 range, until the RPMs started moving again. The 4.0 is running around 800rpms when stopped in D, and it seems any times revs are under 1000 the needle on the temp gauge rises. Think I'm gonna go ahead and order that Flowkooler water pump. I think burping the system at the temp sensor helped a little. Link to comment Share on other sites More sharing options...
Airborne Janitor Posted October 24 Author Share Posted October 24 So for the past week she's stayed under 230ish. I confirmed temps at block/temp sensor and at the face of the thermostat housing with an IR temp gun. The Flowkooler water pump arrived today so I'll get that bad boy installed soon and report back, hopefully this fixes it. Link to comment Share on other sites More sharing options...
Pete M Posted October 24 Share Posted October 24 don't forget that burping can be more of a process than a one-and-done Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted October 24 Share Posted October 24 A trick I use to get everything full is to pull the small hose off the thermostat housing and fill the block from there. Link to comment Share on other sites More sharing options...
gogmorgo Posted October 28 Share Posted October 28 Best way to get all the air out is a vacuum fill. The name brand tools are not cheap but I see online they start under $50. They all kinda work the same, you need a decent enough compressor to ensure air flow and the venturi effect sucks your system down, then there’s a valve to block off the venturi and another to suck the coolant up a hose from a jug or pail. Simple system, hard to screw up. I’m sure the cheap ones are fine. https://www.mishimoto.com/mishimoto-coolant-vacuum-purge-refill-tool-kit.html?sku=MMTL-COOL-PR&srsltid=AfmBOop7c2Qg7rhbIjmrXtYHw_5jSmPk_9yOX7kVqc6sMfijqieNfnURIV8 Link to comment Share on other sites More sharing options...
Airborne Janitor Posted October 29 Author Share Posted October 29 12 hours ago, gogmorgo said: Best way to get all the air out is a vacuum fill. The name brand tools are not cheap but I see online they start under $50. They all kinda work the same, you need a decent enough compressor to ensure air flow and the venturi effect sucks your system down, then there’s a valve to block off the venturi and another to suck the coolant up a hose from a jug or pail. Simple system, hard to screw up. I’m sure the cheap ones are fine. https://www.mishimoto.com/mishimoto-coolant-vacuum-purge-refill-tool-kit.html?sku=MMTL-COOL-PR&srsltid=AfmBOop7c2Qg7rhbIjmrXtYHw_5jSmPk_9yOX7kVqc6sMfijqieNfnURIV8 Ordered Link to comment Share on other sites More sharing options...
89 MJ Posted October 29 Share Posted October 29 8 hours ago, Airborne Janitor said: Ordered Please let us know how it works once you get it. Link to comment Share on other sites More sharing options...
ratrapp Posted October 29 Share Posted October 29 unless your impellers are rusted off your old water pump and its not leaking then replacing the water pump probably isnt going to fix it.they don't overheat with stock water pumps so putting a more gpm pump probably isnt going to fix anything unless it just masks the original problem. Link to comment Share on other sites More sharing options...
Airborne Janitor Posted October 30 Author Share Posted October 30 11 hours ago, ratrapp said: unless your impellers are rusted off your old water pump and its not leaking then replacing the water pump probably isnt going to fix it.they don't overheat with stock water pumps so putting a more gpm pump probably isnt going to fix anything unless it just masks the original problem. Theres something definitely going on in regards to the waterflow. Today she started overheating into the 240 range. Only way to bring the temps down was to keep the RPMs above 2000, so at a light I'd pop her into neutral and apply the accelerator. Within minutes temps would drop 30*. If anything replacing the pump will allow me to peak into the block a little to see if theres some type of obstruction. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted October 30 Share Posted October 30 It could also be your fan clutch. Maybe it is not locking up enough. I have heard that you need a lot of air flow to cool a triple core radiator. Heard that this is a issue with the CSF triple core radiator not sure about the Mishimoto. You could check to make sure you are getting air flowing through the radiator by placing a sheet of paper or a towel in front of the radiator and seeing if it gets sucked up to the radiator. While the engine is running. Link to comment Share on other sites More sharing options...
jkchr1s Posted November 3 Share Posted November 3 This may sound crazy, but check your spark plugs. I had an unknown engine I installed that was running hot intermittently like this and cylinder #1's plug looked very different than the others. Turns out I had a cracked head, cracked piston, and failed head gasket where it was pushing exhaust gasses in to the coolant. It seemed like it could never be "burped" no matter what I did. The engine ran seemingly well otherwise. Hopefully this isn't the case with yours, but it could be something else to look in to if it feels like it keeps getting air pockets for no reason. Potentially a head gasket issue? Link to comment Share on other sites More sharing options...
ratrapp Posted November 3 Share Posted November 3 exactly.once you purge the air put of a system and you continue to get air pockets its a reason for it.subarus with 4 cyl engine have head gasket problems where they might run several days before just randomly overheating or the temp gauge will start flucuating then stay steady. Link to comment Share on other sites More sharing options...
Airborne Janitor Posted November 13 Author Share Posted November 13 Got the Flowkooler water pump installed along with a high-flow 180* thermostat. Pulled the magnetic drain plug from the Mishimoto radiator and found a ton of rust/debris on it, so I flushed the radiator and the water jacket. Was unable to properly use the vacuum purge/refill kit, I couldn't keep vacuum pressure consistent, then realized the thermostat had moved out of its seat when I bolted the housing on when coolant started pouring out, oops. Temps ranged from 180-210* after the install. Although I'm happy it's running cooler it's still doing that 30* shift when revs fall/rise above 2000rpms. Even though the fan clutch was just replaced (by the shop who did the head work, not me) I'm going to throw another fan clutch on. I have an OEM one with some miles on it I'll bolt on just to see if there's any performance change. Link to comment Share on other sites More sharing options...
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