Whitaker717 Posted February 19 Author Share Posted February 19 On 2/19/2025 at 5:00 PM, 75sv1 said: OK, I'm in Indiana. So, basically, the same weather. It would be OK to run a 205 F. I still prefer a 193 to 197F. My Xjs run about 205 F in the Summertime. Once your T-stat is fully open, your system will rise to its cooling efficiency level or Temp. So, the T-Stat sort of control the low side of the Temp. What I am hoping, is your T-Stat is in Failed Open or broke apart. Thus in Failed open mode. So, the oil is not getting warm to hot enough to boil off water. So, possibly adding to much moister into the blow by or emissions. Its a stretch. Check your oil. Is it clear or even a bit off color, or dark brown or even black? Then ok. If milky brown, then it is getting water in it. I'd check the spark plugs. I might try a Valve Cover breather for a temp fix. Still, be aware it might affect Idle and acceleration. Expand Any t stat reccomendations? Link to comment Share on other sites More sharing options...
75sv1 Posted February 19 Share Posted February 19 Dealership if you can. Not sure if Stant is any good anymore. There is a new vender Colorstat. Not sure on it though. Some might be made in the US. If you use EBay, then a Carrol. I do have a few. Do you have a Federated Parts store around you? I am not sure what they carry. Robert Shaw is being produced again. Not sure of the quality. I did buy a Stewart from the same company. Stewart is for High Flow water pumps. See if others have a recommendation. I might be able to spare a Carrol or an ASG. Link to comment Share on other sites More sharing options...
Whitaker717 Posted February 19 Author Share Posted February 19 On 2/19/2025 at 5:32 PM, 75sv1 said: Dealership if you can. Not sure if Stant is any good anymore. There is a new vender Colorstat. Not sure on it though. Some might be made in the US. If you use EBay, then a Carrol. I do have a few. Do you have a Federated Parts store around you? I am not sure what they carry. Robert Shaw is being produced again. Not sure of the quality. I did buy a Stewart from the same company. Stewart is for High Flow water pumps. See if others have a recommendation. I might be able to spare a Carrol or an ASG. Expand I appreciate it. I will tackle it when it gets a bit warmer. Lol. Link to comment Share on other sites More sharing options...
AZJeff Posted February 19 Share Posted February 19 On 2/19/2025 at 4:04 PM, Whitaker717 said: Any good recommendations for a 195 degree thermostat or higher? Expand Lots of guys claim the only thermostat worth buying for the 4.0 is Mopar OEM, but I have had NO problems using the "Motorad" brand from Rock Auto. Whatever brand you choose, make sure it has a "jiggle pin" hole in the flange of the thermostat to aid in "burping" the cooling system. If you cannot find one with a jiggle pin hole, and small (1/16") hole drilled near the perimeter of the thermostat flange can be made. Then make sure you orient the thermostat with this jiggle pin hole on the "12 o'clock" position when installing it in the head. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted February 19 Share Posted February 19 On 2/19/2025 at 7:38 PM, AZJeff said: make sure it has a "jiggle pin" hole in the flange of the thermostat to aid in "burping" the cooling system Expand I have found the best way to make sure the engine block is all filled up is to remove the smaller hose from the thermostat housing and fill from there. Filling from there will bypass the thermostat, filling the block completely. Link to comment Share on other sites More sharing options...
Whitaker717 Posted February 19 Author Share Posted February 19 On 2/19/2025 at 8:35 PM, Eagle_SX4 said: I have found the best way to make sure the engine block is all filled up is to remove the smaller hose from the thermostat housing and fill from there. Filling from there will bypass the thermostat, filling the block completely. Expand That would be a whole other issue for me. Burping a closed system. Lol. I’ve seen it done but never tried it. Seems like people jack the back up really high. Not sure that’s the correct way or not Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted February 19 Share Posted February 19 On 2/19/2025 at 8:54 PM, Whitaker717 said: Seems like people jack the back up really high. Expand That is if they are filling the block through the temp sending unit which is at the back of the engine. There is no jacking required when filling from the front because it is already the highest point. Link to comment Share on other sites More sharing options...
Pete M Posted February 20 Share Posted February 20 On 2/19/2025 at 9:13 PM, Eagle_SX4 said: That is if they are filling the block through the temp sending unit which is at the back of the engine. Expand no one is filling from that tiny hole. at least I hope not. it is used for burping and is conveniently located exactly where bubbles like to stay. but if you have bubbles there, it should read too hot, not too cold. Link to comment Share on other sites More sharing options...
Whitaker717 Posted February 20 Author Share Posted February 20 On 2/20/2025 at 1:35 AM, Pete M said: no one is filling from that tiny hole. at least I hope not. it is used for burping and is conveniently located exactly where bubbles like to stay. but if you have bubbles there, it should read too hot, not too cold. Expand Is there a video or tutorial Pete somewhere that shows how to do it? I will try it when it gets a bit warmer. Do people fill from that small tube usually or just pour in the bottle? Link to comment Share on other sites More sharing options...
Pete M Posted February 20 Share Posted February 20 always pick a hose, undo it, and fill from there. there might be a writeup on bleeding the system in the link in my signature. it's pretty straight forward. park the truck downhill, lowly undo the sensor juuuust enough for air to escape while the cold engine is running. do not do this if the engine is hot because there's a risk of completely unscrewing the sensor and you don't want a hot coolant shower. :L a variation on that is to completely remove the sensor while filling from a hose and hold that hose higher than the sensor opening so eventually coolant will come out the sensor hole. Link to comment Share on other sites More sharing options...
Whitaker717 Posted February 20 Author Share Posted February 20 On 2/20/2025 at 2:47 PM, Pete M said: always pick a hose, undo it, and fill from there. there might be a writeup on bleeding the system in the link in my signature. it's pretty straight forward. park the truck downhill, lowly undo the sensor juuuust enough for air to escape while the cold engine is running. do not do this if the engine is hot because there's a risk of completely unscrewing the sensor and you don't want a hot coolant shower. :L a variation on that is to completely remove the sensor while filling from a hose and hold that hose higher than the sensor opening so eventually coolant will come out the sensor hole. Expand How much coolant do you use Pete? Link to comment Share on other sites More sharing options...
Whitaker717 Posted February 20 Author Share Posted February 20 On 2/19/2025 at 7:38 PM, AZJeff said: Lots of guys claim the only thermostat worth buying for the 4.0 is Mopar OEM, but I have had NO problems using the "Motorad" brand from Rock Auto. Whatever brand you choose, make sure it has a "jiggle pin" hole in the flange of the thermostat to aid in "burping" the cooling system. If you cannot find one with a jiggle pin hole, and small (1/16") hole drilled near the perimeter of the thermostat flange can be made. Then make sure you orient the thermostat with this jiggle pin hole on the "12 o'clock" position when installing it in the head. Expand Is the 205 thermostat overkill for these trucks or should I use one of those. Link to comment Share on other sites More sharing options...
AZJeff Posted February 20 Share Posted February 20 On 2/20/2025 at 3:17 PM, Whitaker717 said: Is the 205 thermostat overkill for these trucks or should I use one of those. Expand Factory is 195* Link to comment Share on other sites More sharing options...
Whitaker717 Posted February 22 Author Share Posted February 22 On 2/19/2025 at 12:29 PM, 75sv1 said: OK, 170 is an issue. Some say to run at 180 F. I like 200 to 205. I think two things. First replace the radiator cap, if not done in the past 5 years. Second, replace the thermostat. Not sure what is good at the parts stores anymore. I have a stash of some old makes. Carrol is one of them. They fit, yet have to trim the gasket a bit. Expand I got a new thermostat coming but this was my temperature yesterday after driving 30 minutes. It was 6 degrees outside. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted February 22 Share Posted February 22 On 2/22/2025 at 12:36 PM, Whitaker717 said: I got a new thermostat coming but this was my temperature yesterday after driving 30 minutes. It was 6 degrees outside. Expand That is about where my gauge is all the time. I would get an infrared thermometer and check the temp with that to verify your engine is actually running cold. Even though my gauge reads low my thermostat housing and engine block reach ~ 200 degrees regularly. Link to comment Share on other sites More sharing options...
Whitaker717 Posted February 22 Author Share Posted February 22 On 2/22/2025 at 3:50 PM, Eagle_SX4 said: That is about where my gauge is all the time. I would get an infrared thermometer and check the temp with that to verify your engine is actually running cold. Even though my gauge reads low my thermostat housing and engine block reach ~ 200 degrees regularly. Expand Does your heat still get hot. Mine was luke warm at best. I froze all the way to work. These little trucks should cook you out of the cab I would think. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted February 22 Share Posted February 22 On 2/22/2025 at 4:08 PM, Whitaker717 said: Does your heat still get hot. Mine was luke warm at best. I froze all the way to work. These little trucks should cook you out of the cab I would think. Expand Yes my heater gets very hot. Have you checked the temperature of your heater core hoses and upper radiator hose by touching them? They should feel about the same temp. If not it could be the heater control valve which shuts off the flow of coolant into the heater core when it's not being used. Link to comment Share on other sites More sharing options...
Whitaker717 Posted February 22 Author Share Posted February 22 On 2/22/2025 at 4:27 PM, Eagle_SX4 said: Yes my heater gets very hot. Have you checked the temperature of your heater core hoses and upper radiator hose by touching them? They should feel about the same temp. If not it could be the heater control valve which shuts off the flow of coolant into the heater core when it's not being used. Expand I haven’t touched them. My heater core is brand new though. Like last August. Where is this heater control valve? Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted February 22 Share Posted February 22 It is located on one of the hoses coming from the heater core. It looks like this. Link to comment Share on other sites More sharing options...
Whitaker717 Posted February 22 Author Share Posted February 22 On 2/22/2025 at 4:51 PM, Eagle_SX4 said: It is located on one of the hoses coming from the heater core. It looks like this. Expand Gotcha. How you know if it works or not. I remember last year un hooking the hose that goes to that so heat would bypass the ac I think. Or the heat would blow through the ac setting. Pretty sure that works Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted February 22 Share Posted February 22 On 2/22/2025 at 4:57 PM, Whitaker717 said: Gotcha. How you know if it works or not. I remember last year un hooking the hose that goes to that so heat would bypass the ac I think. Or the heat would blow through the ac setting. Pretty sure that works Expand If the hoses to your heater core are hot then it is open allowing hot coolant into the heater core. If the hoses are cold then it is closed and you will not get any heat into the cab. Link to comment Share on other sites More sharing options...
Whitaker717 Posted February 22 Author Share Posted February 22 On 2/22/2025 at 5:06 PM, Eagle_SX4 said: If the hoses to your heater core are hot then it is open allowing hot coolant into the heater core. If the hoses are cold then it is closed and you will not get any heat into the cab. Expand Just had a nice 20 minute drive and the hoses are so hot they just about burn my hand. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted February 22 Share Posted February 22 On 2/22/2025 at 5:31 PM, Whitaker717 said: Just had a nice 20 minute drive and the hoses are so hot they just about burn my hand. Expand The issue might be your HVAC blend door not moving. I haven't looked into how the HVAC controls work but I recommend that as the next step. Link to comment Share on other sites More sharing options...
GonzoTheGreat Posted February 22 Share Posted February 22 On 2/22/2025 at 4:57 PM, Whitaker717 said: I remember last year un hooking the hose that goes to that so heat would bypass the ac I think. Or the heat would blow through the ac setting. Pretty sure that works Expand Does this mean that you removed the little pink plastic hose from the valve? because that is the vacuum line that operates the heater valve. That is what allows the flow of coolant to the heater core. You need that. I don’t remember off-hand if the valve is closed WITH or WITHOUT vacuum. I’m away from my trucks at the moment. Maybe someone else can jump in with that info. you could also have someone force the valve to change positions and see if the heater blows hot. Link to comment Share on other sites More sharing options...
Whitaker717 Posted February 22 Author Share Posted February 22 On 2/22/2025 at 6:15 PM, GonzoTheGreat said: Does this mean that you removed the little pink plastic hose from the valve? because that is the vacuum line that operates the heater valve. That is what allows the flow of coolant to the heater core. You need that. I don’t remember off-hand if the valve is closed WITH or WITHOUT vacuum. I’m away from my trucks at the moment. Maybe someone else can jump in with that info. you could also have someone force the valve to change positions and see if the heater blows hot. Expand It has been on all this winter. Last winter I removed it on the advice of a member to bypass something so I would get more airflow from my blower motor. By disconnecting the hose the heat still worked but I was able to have the max ac option on and heat still came out instead of ac. At least that’s what I remember. Link to comment Share on other sites More sharing options...
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