Fake overheating

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bajareece

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Joplin mo
Need some help here. I have a 14 it’s had heads done T-stat all the coolant replaced like 2/3 times. Temp sensor pigtail wires to ecm even ecm replaced. I have heat never loose it. It’s been block tested twice. It still says it’s 300 degrees. Climbs to it. I’m at a loss here. It’s 194 at the temp sensor it’s never ever not even close. Any ideas as to what is next to waste time and money on? Oh all is oem parts also.

I’m being told it’s the gauges. But is the gauges not ran off ecm?
 
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Burp the cooling system again. Maybe 2-3 more times.
The gauges receive signals from the various computers and convert them into data that is displayed to you. But it's still electronic data being converted into a signal that is used by the gauge itself to move a mechanical needle. Things break.
Simple check. Use your JScan (or whatever device you like) to ask the computer what the temperature is. And compare that to the numbers from an infrared temperature gun. If those all match and your gauge doesn't, then it's the gauge.
 
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BLACKJKU said:
Are you sure all the air is burped out of the system?

Have you checked the engine, hoses and radiator with an infrared temperature gun?
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Yes on all. I have had 0 heat issues. Just keeps saying it’s pegged out and it’s not. Radiator cap is cool to the touch also.
 
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Dirty Dog said:
Burp the colling system again. Maybe 2-3 more times.
The gauges receive signals from the various computers and convert them into data that is displayed to you. But it's still electronic data being converted into a signal that is used by the gauge itself to move a mechanical needle. Things break.
Simple check. Use your JScan (or whatever device you like) to ask the computer what the temperature is. And compare that to the numbers from an infrared temperature gun. If those all match and your gauge doesn't, then it's the gauge.
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We did that scanner says what gauge do but at the sensor it’s 194 heads aren’t much differ in temp. No where near 300 like dash is telling me.
 
I think the chief thing to consider is whether the system is throwing a code. If it is, then likely the glitch is between the sensor and ECM. If it isn't, then it's likely the gauge in the dash or cabin that is the problem. If the sensor were reporting an overheated state, you should expect to see the check-engine light coming on, and EBD II codes thrown. But the dashboard gauge itself is there simply for you, the driver, to monitor engine temperature. If the sensor were really reporting and overheated state you should see a P0217 code being thrown.

Also, just for clarity, what kind of temperature gauge do you have in the cabin? If it is reading in degrees, is it a replacement for the original dash gauge?
 
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Duster said:
I think the chief thing to consider is whether the system is throwing a code. If it is, then likely the glitch is between the sensor and ECM. If it isn't, then it's likely the gauge in the dash or cabin that is the problem. If the sensor were reporting an overheated state, you should expect to see the check-engine light coming on, and EBD II codes thrown. But the dashboard gauge itself is there simply for you, the driver, to monitor engine temperature. If the sensor were really reporting and overheated state you should see a P0217 code being thrown.

Also, just for clarity, what kind of temperature gauge do you have in the cabin? If it is reading in degrees, is it a replacement for the original dash gauge?
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The gauge and scanner is saying it’s overheating. The engine radiator cap and all is cold. I have heat I have always had it. The temp at heads with temp gun is 194. The only time I get any codes is when gauge is saying it’s hot but it’s not. If it’s 300 degrees that cap would be hot not cool to the touch. I guess I’m wondering what is the gauges ran off of the ecm? Cause the fan come on high and low but it’s not hot only moving cold air. The information in menu says it in digital it’s oem cluster.
 
bajareece said:
I did it again. The gauge said 267 and I took cap off and it cold coolant.
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If your engine has warmed up but the coolant is still cool, then the coolant is not circulating through your engine. That's almost certainly a dead thermostat, or (much less likely) a mechanical obstruction of your coolant passages.
 
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bajareece said:
"The gauge and scanner is saying it’s overheating. ..."
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The point is to localize the problem and there are several points where "overheating" could show up. There could be genuine overheating due to a failed thermostat, pump, or radiator. If that is true, then your infrared scan should see the engine temperature within operating range after it has warmed up, and continues heating beyond where should stabilize. This a problem with the cooling system. You should be seeing a check engine light coming on, and if you have an OBDII scanner, there should be a code thrown: specifically "P0217."

You say, "The only time I get any codes is when gauge is saying it’s hot but it’s not." If the sensor is haywire, it will be telling both the ECM and the gauge in the cab that the egine has over heated. That will cause that code to be thrown, whether the engine is too hot or not. So, if the engine is not over heated, but the gauge and ECM are saying it is, you may need a new sensor - even if it has been recently replaced. You should double check the connections first. If you have the old wires try swapping them out. If that changes things, maybe it's the wires. If it doesn't, then replace the sensor.
 
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Duster said:
The point is to localize the problem and there are several points where "overheating" could show up. There could be genuine overheating due to a failed thermostat, pump, or radiator. If that is true, then your infrared scan should see the engine temperature within operating range after it has warmed up, and continues heating beyond where should stabilize. This a problem with the cooling system. You should be seeing a check engine light coming on, and if you have an OBDII scanner, there should be a code thrown: specifically "P0217."

You say, "The only time I get any codes is when gauge is saying it’s hot but it’s not." If the sensor is haywire, it will be telling both the ECM and the gauge in the cab that the egine has over heated. That will cause that code to be thrown, whether the engine is too hot or not. So, if the engine is not over heated, but the gauge and ECM are saying it is, you may need a new sensor - even if it has been recently replaced. You should double check the connections first. If you have the old wires try swapping them out. If that changes things, maybe it's the wires. If it doesn't, then replace the sensor.
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That’s where I’m at with it sensor bad out of the box. I’m going to also redo all the wires to ecm from sensor and pigtail. No heat issues not ever so pump t stat has to be good and no air in system it’s been purged 4 times now. Thanks I think your right one this.
 
bajareece said:
". . . I’m going to also redo all the wires to ecm from sensor and pigtail. No heat issues not ever so pump t stat has to be good and no air in system it’s been purged 4 times now. Thanks I think your right one this. . . ."
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You're welcome. If you are rebuilding or have already rebuilt the wiring partially, you'll want to that check closely too, before you go to the trouble of replacing the sensor. I've goofed up constructing a wire-up a couple of times. The most embarrassing was building a computer. It would not boot. No power to the board or drives. I finally located the fault - I had failed to reconnect the line from the power supply to the pigtails from the board and drives after I installed a drive and had to add in a new pigtail to accommodate everything. There were enough wires I couldn't see the two dangling ends.
 
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