Dammerung Posted October 5, 2019 Share Posted October 5, 2019 My Comanche is getting real warm, and I don’t really know why. I replaced the water pump a few weeks ago, but now it spits steam out of the coolant tank and the electric fan doesn’t turn on, though I don’t know if that’s ever turned on to begin with. Firstly, is there a potential reason why it should spit steam and coolant out of the cap? Also, is there a relay or a fuse to check for the fan? I know it works, pulled it out and hooked up a 12 volt battery. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Ωhm Posted October 5, 2019 Share Posted October 5, 2019 YR? ENG? Link to comment Share on other sites More sharing options...
Dammerung Posted October 5, 2019 Author Share Posted October 5, 2019 YR? ENG? 88 4.0Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 5, 2019 Share Posted October 5, 2019 I’d look into that fan first. Get that fan running and see if your heating issue persists. Link to comment Share on other sites More sharing options...
Dammerung Posted October 5, 2019 Author Share Posted October 5, 2019 I’d look into that fan first. Get that fan running and see if your heating issue persists. What makes it work though? Is there a sensor somewhere that isn’t kicking on or a relay that’s not sending power?Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Ωhm Posted October 5, 2019 Share Posted October 5, 2019 KEY OFF. Disconnect Radiator Temperature Switch connector. On the harness side (connector), using a fused jumper, connect the two terminals together. Cycle KEY ON. BEWARE, FAN SHOULD COME ON. Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 5, 2019 Share Posted October 5, 2019 What Ohm says goes. He is the electrical guru around here. Link to comment Share on other sites More sharing options...
Ωhm Posted October 5, 2019 Share Posted October 5, 2019 Your very kind, but I can also burn your vehicle to the ground. That what worries me the most. Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 5, 2019 Share Posted October 5, 2019 Trial and error by fire. Link to comment Share on other sites More sharing options...
Dammerung Posted October 5, 2019 Author Share Posted October 5, 2019 Your very kind, but I can also burn your vehicle to the ground. That what worries me the most. I’ve got 3 fire extinguishers around, hopefully I’ll be fine.Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Ωhm Posted October 5, 2019 Share Posted October 5, 2019 Link to comment Share on other sites More sharing options...
Dammerung Posted October 5, 2019 Author Share Posted October 5, 2019 KEY OFF. Disconnect Radiator Temperature Switch connector. On the harness side (connector), using a fused jumper, connect the two terminals together. Cycle KEY ON. BEWARE, FAN SHOULD COME ON. Did it. Fan did turn on, so I know the connection is working. My guess is a bad radiator sensor?Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Ωhm Posted October 5, 2019 Share Posted October 5, 2019 Yeah, suspect radiator temperature switch. Link to comment Share on other sites More sharing options...
Eagle Posted October 5, 2019 Share Posted October 5, 2019 It should not overheat with the primary fan alone. A concern I have is the comment that the water pump was replaced a couple of weeks ago. Are you certain (meaning are you absolutely, 100 percent, dead-on CERTAIN) that the parts guy gave you the correct water pump? The 4.0L and the older 4.2L engine have the same mounting pattern for the water pump. But ... the 4.2L water pump rotates "forward", for use with vee belts. The 4.0L water pump rotates in "reverse," for use with a serpentine belt. It's not unheard of for a parts counter drone to assume that all Jeep engines use the same water pump. They look the same on the outside, but the impellers are different. Link to comment Share on other sites More sharing options...
Dammerung Posted October 5, 2019 Author Share Posted October 5, 2019 It should not overheat with the primary fan alone. A concern I have is the comment that the water pump was replaced a couple of weeks ago. Are you certain (meaning are you absolutely, 100 percent, dead-on CERTAIN) that the parts guy gave you the correct water pump? The 4.0L and the older 4.2L engine have the same mounting pattern for the water pump. But ... the 4.2L water pump rotates "forward", for use with vee belts. The 4.0L water pump rotates in "reverse," for use with a serpentine belt. It's not unheard of for a parts counter drone to assume that all Jeep engines use the same water pump. They look the same on the outside, but the impellers are different. I got the Murray one from O’rileys. $35. The box art doesn’t look the same as the pump either, so I don’t know.Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Dammerung Posted October 5, 2019 Author Share Posted October 5, 2019 It should not overheat with the primary fan alone. A concern I have is the comment that the water pump was replaced a couple of weeks ago. Are you certain (meaning are you absolutely, 100 percent, dead-on CERTAIN) that the parts guy gave you the correct water pump? The 4.0L and the older 4.2L engine have the same mounting pattern for the water pump. But ... the 4.2L water pump rotates "forward", for use with vee belts. The 4.0L water pump rotates in "reverse," for use with a serpentine belt. It's not unheard of for a parts counter drone to assume that all Jeep engines use the same water pump. They look the same on the outside, but the impellers are different. Also, mine hasn’t overheated... YET. But I don’t think steam and some coolant coming out of the reservoir is necessarily a good thing. Link to comment Share on other sites More sharing options...
Eagle Posted October 5, 2019 Share Posted October 5, 2019 Steam and coolant coming out of the reservoir is overheating -- UNLESS the system wasn't fully burped when you refilled after doing the water pump. Link to comment Share on other sites More sharing options...
Dammerung Posted October 5, 2019 Author Share Posted October 5, 2019 Steam and coolant coming out of the reservoir is overheating -- UNLESS the system wasn't fully burped when you refilled after doing the water pump. I think that may be the case. I poured in water from the upper radiator tube before I reattached it. I didn’t know how to really fill it. How would I burp it, then? I’m not familiar with a coolant system like this at all. Also, when I did the pump I remember looking at both before I installed the new one. It is the right direction, unless the PO/junkyard that I got it from installed a 4.2 pump. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
87MJTIM Posted October 6, 2019 Share Posted October 6, 2019 Is the reservoir cap bad? If steam is coming out, the cap may be (probably) busted and can't hold the pressure. Without the pressure, the engine will over heat. (Ask me how I know.) Try replacing the cap with a Volvo cap. (See Cruiser54.com for the part number.) Link to comment Share on other sites More sharing options...
omega_rugal Posted October 7, 2019 Share Posted October 7, 2019 you have a pressure leak, before you start throwing your wallet at it at it make sure you don´t have bad hose or fitting... when the engine is hot ans spitting coolant everywhere do the hoses feel pressurized? Link to comment Share on other sites More sharing options...
Dammerung Posted October 7, 2019 Author Share Posted October 7, 2019 Anyone have a step by step to burp a renix system? Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 7, 2019 Share Posted October 7, 2019 You can unscrew the temp sender at the rear of the head just a little until air comes out of the system. I believe you need to do it facing down a hill for beat results. Link to comment Share on other sites More sharing options...
Dammerung Posted October 7, 2019 Author Share Posted October 7, 2019 You can unscrew the temp sender at the rear of the head just a little until air comes out of the system. I believe you need to do it facing down a hill for beat results. Does the truck have to be running? Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 7, 2019 Share Posted October 7, 2019 No. The air bubble should go to the highest point in the engine to get out. Right now that bubble could be right be the thermostat housing. Link to comment Share on other sites More sharing options...
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