Resolved Grand daughters 2003 3.8 v6 overheating

[def_68]

Not sure if you mentioned that you change the coolant temperature sensor. Are you relying on just the gauge telling you that it’s overheating?

 

[Rck]

Funny you mentioned that. Yes I am only using gauge. I am picking up a lazer temp gun from a friend Friday. We arrived at that also.
Thank you and Ill let you know.

 

[def_68]

Thumb up.

 

[Rck]

Not sure my reply went thru.
Yes gauge only. Getting a laser temp gun from friend Friday.
Thank you and I will let you know.

 

[Mustang5L5]

Sounds good then. Test the cap as well if that’s part of the kit you have

 

[Rck]

Ok gang. Bought an infrared thermometer to check engine heat. Gauge shows overheating yet all points I check show nowhere near 200° including radiator and thermo housing.
Electric fan comes on just over 90° which is wrong.
Does the temp sensor on the driverside head dictate fan also? I believe that to be problem but hate just changing parts.
This car did have blown head gasket. Had heads planed, new water pump and thermostat installed.
2003 mustang 3.8 v6

 

[def_68]

90° is obviously too cool I believe the temperature sensor in the cylinder head controls the fan unless it has a separate radiator fan switch which also measures temperature also what are the temperatures when it’s overheating

 

[Rck]

Highest temp on engine is 180's.

 

[Rck]

Reading at sensor when gauge in car shows normal is 165°

 

[def_68]

I have access to an online service manual. I’ll look up the radiator fan switch and system to tell u real quick where it is located.

 

[Rck]

Antifreeze is at 77°

 

[Rck]

I am back. Changed temp sensor and things are a bit better. Gauge shows last mark prior to red. All readings are with a infrared gun
Thermo housing is 195
Temp sensor is at 218
Freeze out plug at 180
No air in system. If I loosen rad cap I get antifreeze at pressure and temp shows normal on gauge. Temp at temp sensor 198. No antifreeze missing.

 

[def_68]

Looks good per those readings. Gauges are finicky especially with mild corrosion and older wiring temps outside etc.

 

[Rck]

Has anyone installed an aux temp gauge on the engine. 3.8 V6?

 

[def_68]

Auto meter sells great gauges but you’ll have to mount it somewhere or someway. Find out if there is a port anywhere on the engine near the thermostat and install one.

 

[def_68]

They also have a probe type that goes on the radiator

 

[Mustang5L5]

Do you have a half-decent OBD2 reader? You can plug that into the port, and pull up the coolant temp PID and see directly what temp it's reading live, as it happens.

 

[TIGGER]

Do you have a half-decent OBD2 reader? You can plug that into the port, and pull up the coolant temp PID and see directly what temp it's reading live, as it happens.

That is a good idea.

 

[def_68]

Even then the 5 volt reference could be skewed causing false info

 

[Rck]

Thanks folks.
Going to investigate scanner idea. Radiator cap stays 80 - 90