My car think it's overheating...

[MoonDoggy-X]

I was driving home last night when the temperature gauge shot up and said the car was over heating. I was about a block from home and the engine wasn't acting up so I kept driving home. It was dar so I waited til morning to check her out.

When I started the car this morning, after sitting all night, the temp guage was still maxed out. I topped off the oil and coolant, and unplugged the battery for about an hour. Checked the radiator fan and it's fine. Started the car again, and it still maxed out.

Any suggestions or ideas what it might be? I figured if it were the thermostat or water pump, the car would gradually overheat instead of starting off that way.

 

[EdP]

I was driving home last night when the temperature gauge shot up and said the car was over heating. I was about a block from home and the engine wasn't acting up so I kept driving home. It was dar so I waited til morning to check her out.

When I started the car this morning, after sitting all night, the temp guage was still maxed out. I topped off the oil and coolant, and unplugged the battery for about an hour. Checked the radiator fan and it's fine. Started the car again, and it still maxed out.

Any suggestions or ideas what it might be? I figured if it were the thermostat or water pump, the car would gradually overheat instead of starting off that way.

Could be the temperature sensor. I don't know where it is located.

 

[kakerlak]

Could be the temperature sensor. I don't know where it is located.

+1 for this notion. If it suddenly pegged itself and then starts pegged cold, gotta be the sensor

 

[arcman]

Sensor is located on the water pipe behind the left cylinder head. Check it for proper resistance using a ohm meter.

Part number looks to be: 3922038030 Check to make sure. I would stick with the Hyundai part, not aftermarket.



If it checks bad, I bet you could replace the sensor without draining the coolant. Have the replacement ready with Teflon tape wrapped around the threads and just hold your finger over the hole after removing the bad piece then quick whip the new one in. Toughest part may be getting your hands back in there.

Don't overtighten and break the casting!

 

[carguy75]

Sensor is located on the water pipe behind the left cylinder head. Check it for proper resistance using a ohm meter.

Part number looks to be: 3922038030 Check to make sure.

View attachment 50906

If it checks bad, I bet you could replace the sensor without draining the coolant. Have the replacement ready with Teflon tape wrapped around the threads and just hold your finger over the hole after removing the bad piece then quick whip the new one in. Toughest part may be getting your hands back in there.

Don't overtighten and break the casting!


View attachment 50905

The 5.0 engine that the OP has actually have the coolant sensor in the front just over the alternator. But your advice is spot on; do not over tighten the sensor unless you want to pull the front timing covers and upper oil pan off to replace the front lower timing cover that the sensor is mounted to. I am still just finishing off that repair due to over tightening an oil sensor that damaged my front lower timing cover.

 

[MoonDoggy-X]

Started my car today. Temperature guage still maxed out. Engine shaking and idling low.

Put moy OBD2 scanner on it. I got a chassis codes(pending), coolant temp sensor volts out of range, and a misfire in cylinder 3 stored in the comp.

I cleared the codes. The temperature guage instantly went down. Car instantly idling smoothly and rpm picked up.

I let the car idle up to operating temp. The codes have not returned yet. However, I still have no heat in the vehicle.

 

[carguy75]

Started my car today. Temperature guage still maxed out. Engine shaking and idling low.

Put moy OBD2 scanner on it. I got a chassis codes(pending), coolant temp sensor volts out of range, and a misfire in cylinder 3 stored in the comp.

I cleared the codes. The temperature guage instantly went down. Car instantly idling smoothly and rpm picked up.

I let the car idle up to operating temp. The codes have not returned yet. However, I still have no heat in the vehicle.

Weird. But it seems that your coolant sensor is still bad. It may be reading too low now and is causing the ECU to have bad coolant temp readings which is affecting the AC module ability to adjust the blend doors for proper heating. Just a guess.

 

[Twain427]

I had a similar issue on my 2015 5.0 (as posted and discussed on here in another thread). Engine temp shot up one day, gauge sustained an over-temp reading even after sitting all night. Like you, I replaced the sensor to no avail. The end result was a broken oil cooling manifold under the intake. Its purpose is to help distribute coolant for (as the part says) cooling oil. This small, plastic manifold deteriorated over time and finally broke. As such, the system could never pressure up and properly cool. My car has been in the shop since early December 2022 awaiting this part which is on national backorder. As of today, it's projected to be in stock in about a week. Clearly, I cannot say this is the problem with yours, but you do have symptoms was I was experiencing.

Incidentally, it's part No. 25420-B1600

 

[carguy75]

I had a similar issue on my 2015 5.0 (as posted and discussed on here in another thread). Engine temp shot up one day, gauge sustained an over-temp reading even after sitting all night. Like you, I replaced the sensor to no avail. The end result was a broken oil cooling manifold under the intake. Its purpose is to help distribute coolant for (as the part says) cooling oil. This small, plastic manifold deteriorated over time and finally broke. As such, the system could never pressure up and properly cool. My car has been in the shop since early December 2022 awaiting this part which is on national backorder. As of today, it's projected to be in stock in about a week. Clearly, I cannot say this is the problem with yours, but you do have symptoms was I was experiencing.

Incidentally, it's part No. 25420-B1600

The part you listed is just a hose assembly with heat shields, not a manifold. However, still good advice and information.

 

[technocrat]

How many Kms/Miles on the car when this issue popped up?

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[G-276093]

Yes. My 2015. 5.0 been down for months. Kept overheating. Thought it was the sensor until my engine blew due to it being the coolant assembly. The part is nowhere to be found so I’ve been careless for months!

I had a similar issue on my 2015 5.0 (as posted and discussed on here in another thread). Engine temp shot up one day, gauge sustained an over-temp reading even after sitting all night. Like you, I replaced the sensor to no avail. The end result was a broken oil cooling manifold under the intake. Its purpose is to help distribute coolant for (as the part says) cooling oil. This small, plastic manifold deteriorated over time and finally broke. As such, the system could never pressure up and properly cool. My car has been in the shop since early December 2022 awaiting this part which is on national backorder. As of today, it's projected to be in stock in about a week. Clearly, I cannot say this is the problem with yours, but you do have symptoms was I was experiencing.

Incidentally, it's part No. 25420-B1600

 

[G-963595]

assembly

Your engine blew due to a bad coolant assembly