Low Engine Temperature
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Low Engine Temperature
I have a 2000 GMC Yukon 5.3, with 307,000 miles on it that will not come up to operating temp. During the summer, in high outside heat and waiting for my kids at the school, the temp gauge would go over normal and I would have to drive it down the road a little bit, after that, t-stat would open and the temp would drop to normal. Also, never overheated while driving, no matter what the outside temp was. I had the system flushed and a new t-stat installed in the fall. I didn't notice any operating temp issues after the new t-stat and flushing, though I might not have noticed it happening at the time. Shortly after all of the above was done, I noticed some antifreeze weeping from around a radiator fitting, so I replaced the radiator myself. After radiator install, started noticing the low temp issue. Thermostat will not go over 175 going over a long steep mountain I have to drive up and drops to 160 going down the other side. Not much heat coming out of front heater on short trips and none coming out of the rear. Had the system flushed again just to see. I thought I might have a bad t-stat, so I replaced that and still have the same issue. Antifreeze level does not drop. No signs of head gasket leaks. No antifreeze in the oil. Thought about air in the system with hardly any heat in the interior, but that doesn't explain the t-stat temp issues. My brother is in charge of parts and service at a GM dealer and is going to talk to his techs about the issue. Any ideas?
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Joined: Jul 2011
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From: kevinkpk
I have a 2000 GMC Yukon 5.3, with 307,000 miles on it that will not come up to operating temp. During the summer, in high outside heat and waiting for my kids at the school, the temp gauge would go over normal and I would have to drive it down the road a little bit, after that, t-stat would open and the temp would drop to normal. Also, never overheated while driving, no matter what the outside temp was. I had the system flushed and a new t-stat installed in the fall. I didn't notice any operating temp issues after the new t-stat and flushing, though I might not have noticed it happening at the time. Shortly after all of the above was done, I noticed some antifreeze weeping from around a radiator fitting, so I replaced the radiator myself. After radiator install, started noticing the low temp issue. Thermostat will not go over 175 going over a long steep mountain I have to drive up and drops to 160 going down the other side. Not much heat coming out of front heater on short trips and none coming out of the rear. Had the system flushed again just to see. I thought I might have a bad t-stat, so I replaced that and still have the same issue. Antifreeze level does not drop. No signs of head gasket leaks. No antifreeze in the oil. Thought about air in the system with hardly any heat in the interior, but that doesn't explain the t-stat temp issues. My brother is in charge of parts and service at a GM dealer and is going to talk to his techs about the issue. Any ideas?
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Has one. I am wondering if when they put the first replacement Tstat in ( and I forgot to mention they also put in a new water pump), they routed a return line wrong. Or, maybe I routed one wrong when I replaced the radiator. Getting a manual with routing diagram. Think one of the guys at work has a close model year. Compare mine to his.
CF Beginner
Joined: Apr 2022
Posts: 9
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From: Ohio
Low Engine Temperature
I have a 2000 GMC Yukon 5.3, with 307,000 miles on it that will not come up to operating temp. During the summer, in high outside heat and waiting for my kids at the school, the temp gauge would go over normal and I would have to drive it down the road a little bit, after that, t-stat would open and the temp would drop to normal. Also, never overheated while driving, no matter what the outside temp was. I had the system flushed and a new t-stat installed in the fall. I didn't notice any operating temp issues after the new t-stat and flushing, though I might not have noticed it happening at the time. Shortly after all of the above was done, I noticed some antifreeze weeping from around a radiator fitting, so I replaced the radiator myself. After radiator install, started noticing the low temp issue. Thermostat will not go over 175 going over a long steep mountain I have to drive up and drops to 160 going down the other side. Not much heat coming out of front heater on short trips and none coming out of the rear. Had the system flushed again just to see. I thought I might have a bad t-stat, so I replaced that and still have the same issue. Antifreeze level does not drop. No signs of head gasket leaks. No antifreeze in the oil. Thought about air in the system with hardly any heat in the interior, but that doesn't explain the t-stat temp issues. My brother is in charge of parts and service at a GM dealer and is going to talk to his techs about the issue. Any ideas?
Are You sure, that after replacing the radiator, that You d not have air trapped in the system?
THre reason why I'm asking, is cuz' I do HVAC, & what's happening with your vehicle, sounds like what happens with a boiler, or DHW that has air trapped inside one of it's passes.
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