Running hot 4.0
#41
When doing these exercises it is best to try to shoot between the alternator and ac compressor - metal intake manifold outlet or the manifold itself, as well as the heater hoses/tubes. If any of those are over 200 you are too hot and it is a bad thermostat based on your radiator readings.
One of the best things about the inline thermostat mod is you can remove the thermostat completely and run the truck without losing any significant coolant. If it runs fine without a thermostat, you have your problem. If it does not, it is either radiator or hg. Never seen an engine run hot with a good radiator and no thermostat. It might boil the coolant from exhaust gases (bubbles galore in the tank) or throw a misfire code, but almost impossible for an engine circulating coolant through a good radiator to run hot.
One of the best things about the inline thermostat mod is you can remove the thermostat completely and run the truck without losing any significant coolant. If it runs fine without a thermostat, you have your problem. If it does not, it is either radiator or hg. Never seen an engine run hot with a good radiator and no thermostat. It might boil the coolant from exhaust gases (bubbles galore in the tank) or throw a misfire code, but almost impossible for an engine circulating coolant through a good radiator to run hot.
#42
I've seen it mean either, but to verify the sensor = use an OBD2 device to see if it shows a temp. If using an OBD2 device shows a temp within range but the gauge is crazy = gauge or issue with cluster or wiring going to the cluster. If the OBD2 device shows nothing = check coolant temp sensor or wiring.
When doing these exercises it is best to try to shoot between the alternator and ac compressor - metal intake manifold outlet or the manifold itself, as well as the heater hoses/tubes. If any of those are over 200 you are too hot and it is a bad thermostat based on your radiator readings.
One of the best things about the inline thermostat mod is you can remove the thermostat completely and run the truck without losing any significant coolant. If it runs fine without a thermostat, you have your problem. If it does not, it is either radiator or hg. Never seen an engine run hot with a good radiator and no thermostat. It might boil the coolant from exhaust gases (bubbles galore in the tank) or throw a misfire code, but almost impossible for an engine circulating coolant through a good radiator to run hot.
One of the best things about the inline thermostat mod is you can remove the thermostat completely and run the truck without losing any significant coolant. If it runs fine without a thermostat, you have your problem. If it does not, it is either radiator or hg. Never seen an engine run hot with a good radiator and no thermostat. It might boil the coolant from exhaust gases (bubbles galore in the tank) or throw a misfire code, but almost impossible for an engine circulating coolant through a good radiator to run hot.
#43
#44
#45
Ok so the needle moves = good. Have you ever got your hands on an OBD2 bluetooth or scantool to see what the sensor is actually reading? Air pockets love to hang around the temp sensor, but if you're seeing temps over say 210F with the IR temp gun something is certainly going on.
#46
#47
I ordered a scangauge last week but wont be here till tuesday, theres a good chance it will be late too because of the delays going on right now with shipping. I was going to wait to do anything else with the rover until i get the gauge and can watch temps real time. I'm most likely going to be doing the head gaskets when i can get away from other house projects. I might have to resurrect this thread in a couple weeks once I get time to strip the motor down and put back together. Is there a superior gasket out there to others or are they all pretty much the same?
#48
I got my scan gauge and hooked it up. I drove the rover around the block a few times and got it warm and brought it back home. Scan gauge was saying 220, rover gauge was right in the middle from about 160 to 220, my IR gauge reading in between the alternator and ac compressor read 160. We are doing the heads soon since we obviously have a problem somewhere. I'll let you guys know what happens after the heads.
#49
I got my scan gauge and hooked it up. I drove the rover around the block a few times and got it warm and brought it back home. Scan gauge was saying 220, rover gauge was right in the middle from about 160 to 220, my IR gauge reading in between the alternator and ac compressor read 160. We are doing the heads soon since we obviously have a problem somewhere. I'll let you guys know what happens after the heads.
get the 78 c stamped or the Atlantic British warm weather thermostat that should drop it to 195-204
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cvhyatt (05-05-2020)
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