Wounded_Fighter Posted Sunday at 11:51 PM Share Posted Sunday at 11:51 PM New rebuilt block! Still overheating? Spoiler block bored 0.030 deck honed 0.005 KB hypereutectic pistons 0.030 KB424C.030 Crankshaft main bearing clearance 0.003 Total seal piston gapless piston rings (custom order) - 0.036 top ring and gapless ring - 0.028 second ring double roller timing chain & gears valve cover spacer 1.62 ratio Harland sharp roller rockers 10680703 Lunati cam Lift: .527" /.547" Eagle rods SIR 6123JP ARP Headstud Kit ARP Maincap Kit items installed..... *Mishimoto Aluminum 3 core radiator *Aftermarket Hi-Flow Pump *Triple E-fan with shroud *Replaced O2 sensor (Had 0.72AFR / New O2 shows 0.92AFR Rich still?) *12hole injectors (Stock # Injector) *Open loop cooling *overbored throttle body (done by a member on this site in the past) Throttle position & sensor adjusted to 17% it still hits 235F+ Currently... Thoughts? Link to comment Share on other sites More sharing options...
89 MJ Posted yesterday at 02:08 AM Share Posted yesterday at 02:08 AM Verified with an infrared thermometer or just going by the gauge? What brand water pump? What size tires and gears? Link to comment Share on other sites More sharing options...
Wounded_Fighter Posted yesterday at 02:20 AM Author Share Posted yesterday at 02:20 AM 10 minutes ago, 89 MJ said: Verified with an infrared thermometer or just going by the gauge? What brand water pump? What size tires and gears? boiled over... so its accurate lol forgot brand 27's stock gear Link to comment Share on other sites More sharing options...
eaglescout526 Posted yesterday at 02:25 AM Share Posted yesterday at 02:25 AM You say the block is rebuilt. How rebuilt? Entirely to the point where the block was cleaned inside and out including the coolant passages? Link to comment Share on other sites More sharing options...
89 MJ Posted yesterday at 02:42 AM Share Posted yesterday at 02:42 AM Did the engine get new gaskets, bearings, and rings? Or did it get all of the machine work done and proper cleaning procedure too? I just checked out your build thread. Looks like you went with a flowkooler. I have the same rad and water pump. I would also be skeptical of the triple electric fans. Rarely does an electric fan flow more than a clutch fan. And if they’re cheap fans, they probably don’t flow nearly enough. Link to comment Share on other sites More sharing options...
Wounded_Fighter Posted yesterday at 02:57 AM Author Share Posted yesterday at 02:57 AM 28 minutes ago, eaglescout526 said: You say the block is rebuilt. How rebuilt? Entirely to the point where the block was cleaned inside and out including the coolant passages? full rebuild and cleaning 12 minutes ago, 89 MJ said: Did the engine get new gaskets, bearings, and rings? Or did it get all of the machine work done and proper cleaning procedure too? I just checked out your build thread. Looks like you went with a flowkooler. I have the same rad and water pump. I would also be skeptical of the triple electric fans. Rarely does an electric fan flow more than a clutch fan. And if they’re cheap fans, they probably don’t flow nearly enough. yes new new new. I'm kinda sad its overheating after throwing so much into it. its not my first engine build, but definitely the most troubled so far haha Link to comment Share on other sites More sharing options...
eaglescout526 Posted yesterday at 03:23 AM Share Posted yesterday at 03:23 AM Are any of the cooling system parts new? Hoses? Heater control valve? Intake coolant passage cleared? Link to comment Share on other sites More sharing options...
89 MJ Posted yesterday at 03:28 AM Share Posted yesterday at 03:28 AM Interesting. I’d be suspect of the cooling fans then. Any chance you can dig up info on them? Also, what kind of driving are you doing when it overheats? Mostly stop and go traffic or cruising? Link to comment Share on other sites More sharing options...
Wounded_Fighter Posted yesterday at 04:33 AM Author Share Posted yesterday at 04:33 AM 1 hour ago, eaglescout526 said: Are any of the cooling system parts new? Hoses? Heater control valve? Intake coolant passage cleared? no, but purged, flushed, and tested prior to use. only the t-stat and fluid is new 1 hour ago, 89 MJ said: Interesting. I’d be suspect of the cooling fans then. Any chance you can dig up info on them? Also, what kind of driving are you doing when it overheats? Mostly stop and go traffic or cruising? ill dig em up. assuming it was less then 1800rpm & 40mph? didnt exceed 10miles. Link to comment Share on other sites More sharing options...
Airborne Janitor Posted yesterday at 05:21 AM Share Posted yesterday at 05:21 AM I was in a somewhat similar situation after having the head rebuilt on my 4.0. Truck would reach operating temps, then slowly creep past 210* until it went up to 245*. I replaced every part of the cooling system: Flowkooler water pump, new hoses, new Mopar temp sensor, new 195* tstat, new e-fan, until it turned out my Mishimoto radiator was not holding pressure 100% but wasn't producing any leaks. I took the other Mishimoto I had in my XJ and swapped it in, not it doesn't go past 200*. Hopefully this may help? Link to comment Share on other sites More sharing options...
ghetdjc320 Posted yesterday at 07:56 AM Share Posted yesterday at 07:56 AM Been down this road many times, it is likely the triple e fans not getting sufficient voltage (the MJ electrical system doesn’t have enough power to spare to run 3 high cfm fans in its stock form) or the flowkooler pump. The mishimoto rads are generally very solid and a good upgrade. Check all your hoses and clamps as well. It only takes a pinhole of a leak to overheat. Does it cool down when your are cruising at higher speeds? Are you sure you bled all the air out? The other items you listed are lower on the suspect list. Though, I would ask, your 12hole injectors are rated the proper flow rate at the MJ fuel pressure? Only reason I ask is that most are rated at 3 bar or more of fuel pressure.. Link to comment Share on other sites More sharing options...
Htchevyii Posted 23 hours ago Share Posted 23 hours ago On one of the XJ forums, a few people had their Mishimoto radiators plug up and thought that a coolant filter was necessary due to small tubes. It sounds unlikely that you've driven it enough for that to be the issue. It seems like I've heard of more issues with the triple e fan setup than not. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted 23 hours ago Share Posted 23 hours ago I would check your air flow through the radiator. I have heard that the thicker 3 core radiators let less air through, actually reducing cooling capacity. You can do a simple test by putting a piece of paper in front of the radiator to see if it stays in place or falls off. With the E-fan setup an upgraded alternator to handle the addition current draw of the fans is definitely recommended. Link to comment Share on other sites More sharing options...
Wounded_Fighter Posted 22 hours ago Author Share Posted 22 hours ago 1 hour ago, Eagle_SX4 said: I would check your air flow through the radiator. I have heard that the thicker 3 core radiators let less air through, actually reducing cooling capacity. You can do a simple test by putting a piece of paper in front of the radiator to see if it stays in place or falls off. With the E-fan setup an upgraded alternator to handle the addition current draw of the fans is definitely recommended. The fan setup is from either K-Suspension or mishimoto, with dirtbounds shroud because mishimoto shroud didn't fit their own radiator 😅 I'm going to check resistance and voltage across them when I get home from work... If I have to ill be swapping fans, I believe I have spares? Link to comment Share on other sites More sharing options...
Wounded_Fighter Posted 14 hours ago Author Share Posted 14 hours ago Well... Temp gun to the rescue? across the head at temp is relative to the REM & guages 220, and temp gun shows 210 on the head front to back water inlet hose... 95... water outlet hose 95... water pump 110 thermostat housing was at 150 Looks like a failed water pump...? aside from that... typical electrical gremlins... multimeter doesn't read.. soo time to chase grounds and make sure their good. even across battery posts + to - no volts displayed even though REM & dash shows good running voltage as a dummy test, I tried the spare fan against the leads and on another vehicles battery posts for a comparison, Results were satisfactory. Link to comment Share on other sites More sharing options...
89 MJ Posted 14 hours ago Share Posted 14 hours ago 4 minutes ago, Wounded_Fighter said: water inlet hose... 95... water outlet hose 95... water pump 110 thermostat housing was at 150 Looks like a failed water pump...? I’d agree with this conclusion. Maybe I’m misremembering, but I think Flowkooler has a lifetime warranty. Link to comment Share on other sites More sharing options...
Wounded_Fighter Posted 13 hours ago Author Share Posted 13 hours ago 29 minutes ago, 89 MJ said: I’d agree with this conclusion. Maybe I’m misremembering, but I think Flowkooler has a lifetime warranty. seems to be a limited warranty per the website, but doesn't specify a timeframe? I'm just going to go with another one for ease of process... Link to comment Share on other sites More sharing options...
Ωhm Posted 12 hours ago Share Posted 12 hours ago 56 minutes ago, Wounded_Fighter said: multimeter doesn't read.. soo time to chase grounds and make sure their good. even across battery posts + to - no volts If you have a testlamp check GND using that, if not buy one. First reading should be how bright across the battery terminals (reference brightness). Next connect testlamp clamp to + side of battery. Disconnect Fan connector and on the GND side of the connector at the vehicle harness, stick GND terminal. Should illuminate same as battery voltage test. Now testlamps don't draw the current like fan motors do, but they do draw current, better than DVOM's. Any 12vdc lamp, brighter the better, can do also. Link to comment Share on other sites More sharing options...
ratrapp Posted 4 hours ago Share Posted 4 hours ago i don't know if the water pump is your problem but years ago when i still had my 88 i used the flowkooler pump to replace my pump.the pump didnt last a year before the bearing went out.the pump didnt cool any better than the parts store gmb brand.i had used the high flow t stat housing as well and it never sealed up right.i put the stock housing back on and it sealed up fine.i bought these things from hesco years ago and they prety much told me no warranty.most of the factory parts are fine and manage to keep the 4.0 cool under normal circumstances. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted 3 hours ago Share Posted 3 hours ago 58 minutes ago, ratrapp said: i don't know if the water pump is your problem but years ago when i still had my 88 i used the flowkooler pump to replace my pump.the pump didnt last a year before the bearing went out.the pump didnt cool any better than the parts store gmb brand.i had used the high flow t stat housing as well and it never sealed up right.i put the stock housing back on and it sealed up fine.i bought these things from hesco years ago and they prety much told me no warranty.most of the factory parts are fine and manage to keep the 4.0 cool under normal circumstances. Sounds like Hesco lol. The high flow t stat housing is a gimick. You need to keep the coolant in the block long enough to exchange the heat. Same goes for the radiator. High flow pumps only really work when you have increased capacity that matches. Link to comment Share on other sites More sharing options...
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